[摘要]: Vast amount of high quality online resources have been developed to improve science education, while studies have shown that learners have difficulties to precisely locate and timely utilize pedagogical information from these... more
[摘要]: Vast amount of high quality online resources have been developed to improve science education, while studies have shown that learners have difficulties to precisely locate and timely utilize pedagogical information from these resources. This paper ...
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Research Interests: Engineering, Information Retrieval, Technology, User Interface, Knowledge Representation, and 11 moreBiological Sciences, Digital Library, Mathematical Sciences, Physical sciences, Visual System, Knowledge Acquisition, Resource Discovery, Web Service, Information Retrieval System, Design and Implementation, and Service Architecture
... Digital Libraries Faisal Ahmad, Qianyi Gu, and Tamara Sumner BOulder Learning Technologies Lab (BOLT), Dept. of Computer Science, University of Colorado at Boulder, CO-80309, USA {Faisal.Ahmad, Qianyi.Gu, Tamara.Sumner}@colorado.edu... more
... Digital Libraries Faisal Ahmad, Qianyi Gu, and Tamara Sumner BOulder Learning Technologies Lab (BOLT), Dept. of Computer Science, University of Colorado at Boulder, CO-80309, USA {Faisal.Ahmad, Qianyi.Gu, Tamara.Sumner}@colorado.edu Abstract. ...
Abstract We report on the current research activities and results obtained through the Concept Learning service for Concept Knowledge (CLICK) and present a demonstration of the system. This poster session will focus on a demonstration of... more
Abstract We report on the current research activities and results obtained through the Concept Learning service for Concept Knowledge (CLICK) and present a demonstration of the system. This poster session will focus on a demonstration of the CLICK system and the ...
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... Qianyi Gu Department of Computer Science Sichuan Normal University Chengdu, China qianyigu@yahoo.com Faisal Ahmad, Tamara Sumner Department of Computer Science University of Colorado Boulder, USA ... [12] WB Rouse, BS Thomas, and KR... more
... Qianyi Gu Department of Computer Science Sichuan Normal University Chengdu, China qianyigu@yahoo.com Faisal Ahmad, Tamara Sumner Department of Computer Science University of Colorado Boulder, USA ... [12] WB Rouse, BS Thomas, and KR Boff. ...
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Personalized or one-to-one instruction holds great potential for improving the state of education. But due to lack of good teachers this goal can only be approximated with the help of new and innovative computational technology. The... more
Personalized or one-to-one instruction holds great potential for improving the state of education. But due to lack of good teachers this goal can only be approximated with the help of new and innovative computational technology. The research reported in this ...
We have obtained optical pulses via hybrid modelocking in monolithic slab coupled optical waveguide lasers with average powers exceeding 220 mW at a wavelength of 1550 nm.
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We study the combined effects of dynamic gain saturation and two-photon absorption on the amplification of short pulses in semiconductor optical amplifiers and show that two-photon absorption can saturate the amplifier gain and limit the... more
We study the combined effects of dynamic gain saturation and two-photon absorption on the amplification of short pulses in semiconductor optical amplifiers and show that two-photon absorption can saturate the amplifier gain and limit the output pulse energies even for amplifiers with large gain saturation energies. We discuss the upper limits for the pulse energies obtainable from semiconductor optical amplifiers in the presence of two-photon absorption and show that for single transverse mode waveguide amplifiers these upper limits can range from values as small as a few picojoules to several hundred picojoules for pulse widths in the 0.5 ps to 20 ps range, respectively.
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This paper presents the first published report of a totally passively driven actuation and readout of an electromechanical resonator using inductive coupling. The goal of this work is to remotely excite and read a MEMS comb drive... more
This paper presents the first published report of a totally passively driven actuation and readout of an electromechanical resonator using inductive coupling. The goal of this work is to remotely excite and read a MEMS comb drive resonator with a focus on low power operation while simultaneously maximizing standoff distance without the use of active electronics at the sensor location.
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We demonstrate amplification of picosecond pulses centered at 1550 nm using slab-coupled waveguide amplifiers. For bias currents less than 1 A, we obtained a maximum unsaturated gain of 12.3 dB and a pulse saturation energy of ~50 pJ.
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We report on the generation of stable optical pulses at 1.55- mum wavelength via fundamental and subharmonic hybrid mode-locking of a high-power electrically pumped semiconductor diode laser with a slab-coupled optical waveguide... more
We report on the generation of stable optical pulses at 1.55- mum wavelength via fundamental and subharmonic hybrid mode-locking of a high-power electrically pumped semiconductor diode laser with a slab-coupled optical waveguide structure. The highest average power measured in mode-locked operation was 220 mW. This is the highest power reported for a hybrid mode-locked monolithic semiconductor laser. We also measure
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We report on the generation of stable optical pulses from an electrically pumped semiconductor laser via active and hybrid modelocking. Output powers as high as 108 mW and pulse widths of 8 ps were obtained.
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We show that plasmons in two-dimensional graphene can have net gain at terahertz frequencies. The coupling of the plasmons to interband electron-hole transitions in population inverted graphene layers can lead to plasmon amplification... more
We show that plasmons in two-dimensional graphene can have net gain at terahertz frequencies. The coupling of the plasmons to interband electron-hole transitions in population inverted graphene layers can lead to plasmon amplification through the process of stimulated emission. We calculate plasmon gain for different electron-hole densities and temperatures and show that the gain values can exceed $10^{4}$ cm$^{-1}$ in
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We report on the generation of stable passively mode-locked pulses at 1.55-mum wavelength from high-power electrically pumped, large transverse mode semiconductor diode lasers. Optical pulses as short as 5.8 ps were measured directly from... more
We report on the generation of stable passively mode-locked pulses at 1.55-mum wavelength from high-power electrically pumped, large transverse mode semiconductor diode lasers. Optical pulses as short as 5.8 ps were measured directly from the laser. This is the shortest pulsewidth reported (without external compression) from a monolithic mode-locked slab coupled optical waveguide laser. The highest average power measured in
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The Concept Space Interchange Protocol supports the deployment of conceptual browsing interfaces in digital libraries. The protocol provides a programmatic interface to dynamically generate interactive visual components that enable users... more
The Concept Space Interchange Protocol supports the deployment of conceptual browsing interfaces in digital libraries. The protocol provides a programmatic interface to dynamically generate interactive visual components that enable users to navigate a concept space, ...
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Abstract: Digital libraries have improved the availability of resources by leaps and bonds compared to traditional libraries. The improved availability does not have much effect on improved accessibility of resources. Accessibility is... more
Abstract: Digital libraries have improved the availability of resources by leaps and bonds compared to traditional libraries. The improved availability does not have much effect on improved accessibility of resources. Accessibility is related to making the resources ...
The limited scope of digital libraries can be attributed to the brick and mortar vision of the library metaphor. In order to extend scope of digital libraries, in this chapter we examine the current supports and future possibilities... more
The limited scope of digital libraries can be attributed to the brick and mortar vision of the library metaphor. In order to extend scope of digital libraries, in this chapter we examine the current supports and future possibilities afforded by digital libraries to support conventional ...
Page 1. High Power (>150 mW) Electrically Pumped Semiconductor Modelocked Lasers at 1550 nm with Pulse Widths Approaching 6 ps Faisal R Ahmad1 and Farhan Rana2 1Dept. of Physics, Cornell University, Ithaca, NY, 14853 2Dept. ...
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Publikationsansicht. 31496948. A strand map service for educational digital libraries / (2004). Ahmad, Faisal. Abstract. Thesis (MS)--University of Colorado, 2004.. Includes bibliographical references (leaves 78-82). Details der... more
Publikationsansicht. 31496948. A strand map service for educational digital libraries / (2004). Ahmad, Faisal. Abstract. Thesis (MS)--University of Colorado, 2004.. Includes bibliographical references (leaves 78-82). Details der Publikation. ...
... Sumner BOulder Learning Technologies Lab (BOLT), University of Colorado at Boulder, USA, Email: {Faisal.Ahmad, Qianyi.Gu, Tamara.Sumner}@colorado ... Although novel visualizations are a handy tool for teachers, the manner in which... more
... Sumner BOulder Learning Technologies Lab (BOLT), University of Colorado at Boulder, USA, Email: {Faisal.Ahmad, Qianyi.Gu, Tamara.Sumner}@colorado ... Although novel visualizations are a handy tool for teachers, the manner in which these visualizations are created is even ...
Correlations for the estimation of monthly average daily diffuse solar radiation as a function of the sunshine hours and clearness index have been obtained from Karachi. Generally, two types of correlations are used: (a) diffuse radiation... more
Correlations for the estimation of monthly average daily diffuse solar radiation as a function of the sunshine hours and clearness index have been obtained from Karachi. Generally, two types of correlations are used: (a) diffuse radiation as a function of relative sunshine hours and ...
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Renewable Ener,qy Vol. 1. No. I,pp. 115 118, 1991 0960-1481/91 $3.00+.00 Printed in Great Britain. Pergamon Press pie DATA BANK Monthly average daily global beam and diffuse solar radiation and its correlation with hours of bright... more
Renewable Ener,qy Vol. 1. No. I,pp. 115 118, 1991 0960-1481/91 $3.00+.00 Printed in Great Britain. Pergamon Press pie DATA BANK Monthly average daily global beam and diffuse solar radiation and its correlation with hours of bright sunshine for Karachi, Pakistan FIROZ ...
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The Concept Space Interchange Protocol supports the deployment of concept browsing interfaces in digital libraries. The protocol provides a programmatic web service interface to dynamically generate interactive visual components that... more
The Concept Space Interchange Protocol supports the deployment of concept browsing interfaces in digital libraries. The protocol provides a programmatic web service interface to dynamically generate interactive visual components that enable users to navigate a concept space, ...
Abstract. Concept browsing interfaces can help educa-tors and learners to locate and use learning resources that are aligned with recognized learning goals. The Strand Map Service enables users to navigate interactive visual-izations of... more
Abstract. Concept browsing interfaces can help educa-tors and learners to locate and use learning resources that are aligned with recognized learning goals. The Strand Map Service enables users to navigate interactive visual-izations of related learning goals and to request ...
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We generate femtosecond, non-frequency shifted solitons with peak powers greater than 5 MW in a Xe-filled, hollow-core photonic band-gap fiber. This represents, to our knowledge, the first observation of temporal solitons with no... more
We generate femtosecond, non-frequency shifted solitons with peak powers greater than 5 MW in a Xe-filled, hollow-core photonic band-gap fiber. This represents, to our knowledge, the first observation of temporal solitons with no self-frequency shift.
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The measured dispersion of a low-loss, hollow-core photonic band-gap fiber is anomalous throughout most of the transmission band, and its variation with wavelength is large compared with that of a conventional step-index fiber. For an... more
The measured dispersion of a low-loss, hollow-core photonic band-gap fiber is anomalous throughout most of the transmission band, and its variation with wavelength is large compared with that of a conventional step-index fiber. For an air-filled fiber, femtosecond self-frequency--shifted fundamental solitons with peak powers greater than 2megawatts can be supported. For Xe-filled fibers, nonfrequency-shifted temporal solitons with peak powers greater than 5.5 megawatts can be generated, representing an increase in the power that can be propagated in an optical fiber of two orders of magnitude. The results demonstrate a unique capability to deliver high-power pulses in a single spatial mode over distances exceeding 200 meters.
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This chapter discusses an emerging theme in supporting effective multimedia learning: developing scalable, cognitively-grounded tools that customize learning interactions for individual students. We discuss the theoretical foundation for... more
This chapter discusses an emerging theme in supporting effective multimedia learning: developing scalable, cognitively-grounded tools that customize learning interactions for individual students. We discuss the theoretical foundation for expected benefits of customization ...
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Abstract. This paper describes a personalization approach for using online resources in digital libraries to support intentional learning. Per-sonalized resource recommendations are made based on what learners currently know and what they... more
Abstract. This paper describes a personalization approach for using online resources in digital libraries to support intentional learning. Per-sonalized resource recommendations are made based on what learners currently know and what they should know within a targeted ...
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Abstract This paper describes our progress towards automating adaptive personalized instruction based on stu-dent conceptual understandings using digital libraries. The reported approach merges conversational learning theory with advances... more
Abstract This paper describes our progress towards automating adaptive personalized instruction based on stu-dent conceptual understandings using digital libraries. The reported approach merges conversational learning theory with advances in natural language processing to ...