Digital Commons Network^™

High-Performance Thin-Film Garnet Materials For Magneto-Optic And Nanophotonic Applications, Mikhail Vasiliev, Mohammad Nur E Alam, Viacheslav Kotov, Kamal Alameh

Research outputs pre 2011

Since the 1960's, Magneto-optic (MO) garnet materials have been studied extensively. These materials can possess world-record MO performance characteristics in terms of Faraday rotation and optical quality. Among the rear-earth-doped garnets, the Bi-substituted iron garnet is the best candidate for use as a functional material in different integrated-optics, imaging/image processing applications and also in forward-looking applications e.g. the design of metamaterials with non-reciprocal properties. We have established a set of technologies for fabricating ferrimagnetic garnet films of type (BiDy)3(FeGa)5O12 and also garnet-oxide nanocomposite (BiDy)3(FeGa)5O12 : Bi2O3 layers possessing record-high MO quality across the visible spectral range using RF-magnetron sputtering and …

Comparison Between Neural Network Based Pi And Pid Controllers, Mohammed Hassan, Ganesh Kothapalli

Research outputs pre 2011

The Pneumatic actuation systems are widely used in industrial automation, such as drilling, sawing, squeezing, gripping, and spraying. Also, they are used in motion control of materials and parts handling, packing machines, machine tools, and in robotics; e.g. two-legged robot. In this paper, a Neural Network based PI controller and Neural Network based PID controller are designed and simulated to increase the position accuracy in a pneumatic servo actuator. In these designs, a well-trained Neural Network provides these controllers with suitable gains depending on feedback representing changes in position error and changes in external load force. These gains should keep …

Call Admission Control Scheme For Improved Quality Of Service In Wimax Communication At Vehicular Speeds, Iftekhar Ahmad, Daryoush Habibi

Research outputs pre 2011

The IEEE 802.16e standard, also known as mobile WiMAX, has emerged as an exciting mobile wireless communication technology that promises to offer both high throughput and guaranteed quality of service (QoS). Call admission control (CAC) scheme serves as a useful tool for WiMAX, which ensures that resources are not overcommitted and thereby, all existing connections enjoy guaranteed QoS. Existing CAC schemes largely depend on readily available information like currently available resources and bandwidth demand of the new call while making an acceptance or rejection decision once a new request arrives. Since wireless channels are not as reliable as wired communication, …

A New Perspective On First Read Rate Of 2d Barcodes In Mobile Applications, Keng Tiong (Alf) Tan, Douglas Chai

Research outputs pre 2011

The first read rate (FRR) has been one of the traditional benchmark metric for measuring the performance of barcode systems. In recent studies, it has been noted that the FRR alone is not a complete measure of user experience, especially of barcodes in mobile applications. In this paper, we present a further three factors that would influence the user experience of mobile 2D barcodes. Our investigation is based on a quantitative survey of a controlled study participated by 250 lay users of mobile phones, through reading QRCode and Data Matrix barcodes with a variety of camera mobile phones. Observations from …

Bandwidth Allocation And Routing Information For Wireless Mobile Ad-Hoc Networks, Rajeshkumar Ramraj

Research outputs pre 2011

An admission control Algorithm must organize among flows and should afford assurance of how the medium is shared between nodes. In a wired network, nodes can keep an eye on the medium to see how much bandwidth is being used by the network. On the other hand, in an Ad-Hoc network, during communication nodes possibly will use the bandwidth of neighbouring nodes. Consequently, the bandwidth consumption of flows and the accessible resources to a node are not local concepts, other than it being linked to the neighbouring nodes in carrier-sensing range. Current solutions do not address how to perform admission …

The Properties Of Nanocomposite (Bidy)3(Fega)5o12:Bi2o3 Magneto-Optic Garnet Films For Applications In Nanophotonics, Ultrafast Switching And Integrated Optoelectronics, Mikhail Vasiliev, Mohammad Nur E Alam, Viacheslav Kotov, Kamal Alameh

Research outputs pre 2011

We investigate the properties and applications of newly-developed RF-sputtered nano-composites with record-high magneto-optic quality (exceeding 25° at 532 nm and 42° at 635 nm). Bi-substituted dysprosium-gallium iron garnet layers with excess co-sputtered bismuth oxide content are demonstrated to possess very attractive optical and magnetic properties, which makes them suitable for novel magneto-optic and nanophotonic applications.

Photovoltaic Micro-Cell Design For Distrubuted Power In Sensor Networks, Gary A. Allwood, Graham Wild, Steven Hinckley

Research outputs pre 2011

We present a new study of power over optical fiber, for use in optical fiber smart sensor networks, using silicon-based photovoltaic micro-cells. A number of parameters in the design of the micro-cell for implementation in a power converter chip have been investigated. Matching the beam profile to the active region, as well as maximizing the contact area improves the device efficiency. The effect of doping profile and junction type on the device performance, suggests silicon is a cost effective and suitable material for this application.

Multi-Wavelength Laser Scanning Architecture For Object Discrimination, Kavitha Venkataraayan, Sreten Askraba, Kamal Alameh, Clifton Smith

Research outputs pre 2011

A novel method for identifying and discriminating various objects using five different lasers is described. This method uses a laser combination module that allows five laser diodes of different wavelengths to sequentially emit identically polarized light beams through a common aperture, along one optical path. Each laser beam enters a custom-made curved optical cavity for multi-beam spot generation through internal partial beam reflection. The intensity of the reflected light beams from each spot is detected by a high-speed area scan image sensor. Object discrimination based on analyzing the Gaussian profile of reflected laser light at distinguishing wavelengths is demonstrated.

Opto-Vlsi-Based Tunable Linear-Cavity Fibre Laser, David Michel, Feng Xiao, Kamal Alameh

Research outputs pre 2011

A novel approach using an Opto-VLSI processor to achieve a tunable fibre laser is presented. The Opto-VLSI based fibre laser is able to tune wavelengths and maintain a high Side-Mode Suppression Ratio (SMSR) even when the output optical power is low. Experimental results show a continuously tunable fibre laser source with a tuning range as high as 30 nm and a SMSR exceeding 30 dB.

Opto-Vlsi-Based Rf Beamformer For Space Division Multiple Access Network, Budi Juswardy, Feng Xiao, Kamal Alameh

Research outputs pre 2011

In this paper, the architecture of a photonic-assisted smart antenna for Space-division Multiple Access (SDMA) is described. Antenna beam steering is achieved by generating independent true-time delay (TTD) for each element in the antenna arrays, through the use of an Opto-VLSI Processor in conjunction with a 10-km single mode optical fibre. Experimental results demonstrate RF beam steering in 4-element linear patch antenna array operating at 1.85GHz are presented.

Jpeg Compression Of Monochrome 2d-Barcode Images Using Dct Coefficient Distributions, Keng Teong Tan, Douglas Chai

Research outputs pre 2011

Two dimensional (2D) barcodes are becoming a pervasive interface for mobile devices, such as camera phones. Often, only monochrome 2D-barcodes are used due to their robustness in an uncontrolled operating environment of camera phones. Most camera phones capture and store such 2D-barcode images in the baseline JPEG format. As a lossy compression technique, JPEG does introduce a fair amount of error in the decoding of captured 2D-barcode images. In this paper, we introduce an improved JPEG compression scheme for such barcode images. By altering the JPEG compression parameters based on the DCT coefficient distribution of such barcode images, the improved …

The Use Of Alignment Cells In Mmcc Barcode, Siong Khai Ong, Douglas Chai, Alexander Rassau

Research outputs pre 2011

The QR code, a monochrome 2D barcode, is a popular and commonly used barcode system worldwide. QR codes can easily be read using a mobile phone with the appropriate decoder. As there is an increasing need for higher data capacity barcodes, some newer 2D barcodes, such as the MMCC code, have adopted the use of colour. However, the use of colour introduces more challenges for mobile phone decoders than with monochrome codes. In this paper, the use of alignment cells within the MMCC code is proposed to improve the robustness of the colour barcode when used in a mobile environment. …

High Utility Video Surveillance System On Public Transport Using Wimax Technology, Iftekhar Ahmad, Daryoush Habibi

Research outputs pre 2011

Video surveillance on public transport is a useful tool to fight against anti-social behaviour like vandalism, harassment, graffiti and terrorism. Real-time video surveillance on moving public transport faces serious technological challenges mainly due to limited throughput offered by existing communication technologies at high vehicular speeds. Success of real-time video surveillance on public transport heavily depends on future communication technologies like WiMAX. WiMAX has emerged as an exciting technology with promises to offer high throughput and improved quality of services (QoS), key requirements for video surveillance on public transport. WiMAX however, offers limited throughput at high vehicular speeds mainly because of …

Call Admission Control Scheme For The Ieee 802.16e At Vehicular Speeds, Iftekhar Ahmad, Daryoush Habibi

Research outputs pre 2011

The IEEE 802.16e standard has emerged as an exciting mobile wireless broadband technology that promises to deliver both high throughput and guaranteed quality of service (QoS). Call admission control (CAC) scheme serves as a great utility for WiMAX, which ensures that resources are not over committed and thereby, all existing connections enjoy guaranteed quality of service. Existing CAC schemes largely depend on computation of available resources while making an acceptance or rejection decision once a new request arrives. Since wireless channels are not as reliable as wired communication, CAC scheme in WiMAX communication faces a serious challenge of making a …

Simulation Of A Hybrid Polywell And Stacked Gradient Poly-Homojunction Cmos Photodiode, Paul V. Jansz, Steven Hinckley

Research outputs pre 2011

In this paper, we have simulated the performance of a photodiode array that has multiple wells per pixel as well as a stacked-gradient poly-homojunction (StaG) geometry. The pixel response resolution was improved when the first StaG epilayer was within 2 μm of the space charge region (SCR).

Adiabatic Coherent Quantum Tunneling Of Ultracold Atoms Trapped In An Asymmetrical Two-Dimensional Magnetic Lattices, Ahmed Abdelrahman, Kamal Alameh, Peter Hannford

Research outputs pre 2011

We propose a new method to realize a two-dimensional magnetic lattice, having two different configurations of asymmetric magnetic lattice, which exhibits magnetic band gap structure, and a symmetric magnetic lattice. We also describe the tunneling mechanisms of magnetically trapped ultracold atoms, prepared in a degenerate quantum gas such as Bose-Einstein Condensate (BEC). A coherent quantum tunneling of ultracold atoms between the sites of the asymmetrical magnetic lattice can be realized which induces the adiabatically controlled dc Josephson current. At critical phase transitions, namely at certain values of site phase difference and population fraction, a plasma oscillation can be observed in …

Spatial Performance Of Acousto-Ultrasonic Fiber Bragg Grating Sensor, Graham Wild, Steven Hinckley

Research outputs pre 2011

In this letter, we present results for the spatial performance of a fiber Bragg grating (FBG) sensor to continuous-wave acousto-ultrasonic (AU) signals. The FBG AU sensor is an intensity sensor, using a transmit reflect detection system. The AU sensor was used to receive actively generated continuous-wave ultrasonic signals from a PZT transducer. We present results showing the received signal strength as a function of longitudinal, lateral, and angular separation in small aluminum panels. Measurements were taken for distances of less then 100 mm and at angles from 0 to 90 degrees between the sensor and the transducer. These results show …

Pspice Simulation Of An Electro-Acoustic Communications Channel, Graham Wild, Steven Hinckley

Research outputs pre 2011

In this paper, we present results from a circuit simulation of a proposed electro-acoustic communications channel. The communications channel was modeled in PSpice using Redwood's version of Mason's equivalent circuit. The simulations used binary phase shift keyed communications signals with a carrier frequency of 1.12 MHz. Results obtained from the model are comparable with the results obtained experimentally. The frequency response of the model matched the measured frequency response, predicting lower frequency resonances obtained in the experimental data. The transient response of the model compares almost identically with the transient response observed experimentally. This is a significant characteristic as the …

Adaptive Optical Splitter Employing An Opto-Vlsi Processor And A 4-F Imaging System, Haithem Ab Mustafa, Feng Xiao, Kamal Alameh

Research outputs pre 2011

A novel adaptive optical splitter structure employing an Opto-VLSI processor and 4-f imaging system is proposed and experimentally demonstrated. By driving the Opto-VLSI processor with computer generated multicasting phase holograms, an input optical signal launched into an input optical fiber port can be split and coupled into many output optical fiber ports with arbitrary splitting ratios. A proof-of-principle 1 2 adaptive optical splitter structure driven by optimized multicasting phase holograms uploaded onto the Opto-VLSI processor is developed, demonstrating an arbitrary splitting ratio over a wavelength range exceeding 50 nm.

Wireless Acoustic Communications And Power Supply For In-Vivo Biomedical Devices, Graham Wild, Steven Hinckley

Research outputs pre 2011

Pacemakers are common biomedical devices used in the treatment of specific cardiovascular problems. Current research in biomedical engineering is investigating the use of so called brain pacemakers to regulate conditions such as Parkinson's and other neurological conditions. In this paper, we demonstrate the principle of acoustic communications and power harvesting, in vivo. The signals are intended to be used for fixed in vivo biomedical devices, such as pacemakers, were wired and wireless RF communications cannot be used. Results show the performance of the communications channel. The frequency response, transfer function and transient response (at resonance) of the communications channel were …

Effect Of A Polywell Geometry On A Cmos Photodiode Array, Paul V. Jansz, Steven Hinckley, Graham Wild

Research outputs pre 2011

The effect of a polywell geometry hybridized with a stacked gradient poly-homojunction architecture, on the response of a CMOs compatible photodiode array was simulated. Crosstalk and sensitivity improved compared to the polywell geometry alone, for both back and front illumination

Cladding Modes Analysis Of Photonics Crystal Fiber For Refractive Index Sensors Using Finite Element Method, Naeem Khurram, Linh Viet Nguyen, Kamal Alameh, Youngjoo Chung

Research outputs pre 2011

We developed a Finite Element package to analyze cladding mode field extensions into the air-holes of photonics crystal fiber for refractive index sensing. Our analysis could determine the most sensitive cladding mode for liquid sensing.

Adaptive Multi/Demultiplexers For Optical Signals With Arbitrary Wavelength Spacing, Feng Xiao, Kamal Alameh

Research outputs pre 2011

We propose and demonstrate the principle of a novel adaptive wavelength division multiplexer/demultiplexer structure based on Opto-VLSI processing. By driving an Opto-VLSI processor with an appropriate phase hologram, optical signals of arbitrary wavelengths from different input fiber ports can be multiplexed into a common output fiber port. In addition, wavelength division multiplexed channels of arbitrary wavelength spacings can also be demultiplexed and dynamically routed into arbitrary output fiber ports. A proof-of-principle 1×3 adaptive multiplexer/demultiplexers is experimentally demonstrated.

Challenges And Opportunities For Simulation Modelling Integrating Mine Haulage And Truck Shop Operations, Melinda Hodkiewicz, Steven Richardson, Richard Durham

Research outputs pre 2011

Historically considerable work has been done to develop models that simulate truck haulage for both underground and open-pit operations. However, this work frequently simplifies or overlooks aspects such as the reliability of the trucks, priority setting and maintenance strategies in the truck shop, and resourcing of the repair facilities. This paper provides an overview of work in this area that is specific to the mining industry and also relevant work from other sectors that might inform how improvements can be made. The paper proposes some specific projects that will assist in identifying technical issues. Initially, it is important to understand …

Utilizing Multimedia Case Studies To Teach The Professional Side Of Project Management, Cassandra C. Elrod, Susan L. Murray, Barry B. Flachsbart, Karl E. Burgher, Drew M. Foth

Business and Information Technology Faculty Research & Creative Works

This research was conducted to evaluate the effectiveness of using a LITEE multimedia case study to teaching concepts in engineering courses. The LITEE Superstar case study was implemented in an engineering Project Management course. Numerous surveys regarding student expectations, outcomes, and attitudes were collected and results are presented herein. Overall, the study provided evidence that the students felt that the LITEE case study added value to the course via the different methods of teaching material, aided in the understanding of the project selection process, and ultimately helped them be successful in their course project which was conducted for a real …

Investigation Of The Design Of A Bistable Micro-Chemical-Mechanical Device Utilizing Lateral Buckling, Susan Lyn Barnes

Honors Theses

The Gracias Laboratory at Johns Hopkins University has developed microgrippers which utilize chemically-actuated joints to be used in micro-surgery. These grippers, however, take up to thirty minutes to close fully when activated biochemicals in the human body. This is very problematic and could limit the use of the devices in surgery. It is the goal of this research to develop a gripper that uses theGracias Laboratory's existing joints in conjunction with mechanical components to decrease the closing time. The purpose of including the mechanical components is to induce a state of instability at which time a small perturbation would cause …

Development Of A Biofidelic Material Model For Brain Tissue And Its Application To The Impact Response Of The Human Head, Sandeep Kulathu, David L. Littlefield

Early Career Technical Journal (ECTJ)

Proceedings of the ASME Early Career Technical Conference, October 1-2, 2010. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia

pp. 1-8

Asme Early Career Technical Journal (Complete Issue), Asme Ectc Coordinating Committee

Early Career Technical Journal (ECTJ)

Proceedings of the ASME Early Career Technical Conference, October 1-2, 2010. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia

Ab-10-017: Combined Effects Of Noise And Temperature On Human Comfort And Performance (1128-Rp), Dale Tiller, Lily M. Wang, Amy Musser, Matthew Radik

Durham School of Architectural Engineering and Construction: Faculty Publications

This paper summarizes results from an experiment designed to investigate the combined effects of noise and temperature on human thermal comfort and task performance. Thirty subjects (16 females, 14 males) were exposed to all combinations of five thermal conditions (PMV +1 [79.6°F:26.4°C], PMV +0.5 [75.8°F:24.3°C], PMV 0 [72.1°F:22.3°C], PMV -0.5 [68.3°F:20.2°C], and PMV -1 [64.6°F:18.1°C]), three RC noise levels (RC-30, RC-40, and RC-50), and two sound qualities (neutral and rumbly): all sounds mimicked noise from building ventilation systems. After a one-hour adaptation period at each condition, subjects rated their thermal comfort using the ASHRAE Thermal Comfort Scale and the Tenant …

Ab-10-019: Human Performance And Perception-Based Evaluations Of Indoor Noise Criteria For Rating Mechanical System Noise With Time-Varying Fluctuations (1322-Rp), Lily M. Wang, Cathleen C. Novak

Durham School of Architectural Engineering and Construction: Faculty Publications

The goal of this study was to investigate the effects of noise from building mechanical systems with time-varying fluctuations on human task performance and perception, and to determine how well current indoor noise rating methods account for this performance and perception. Six different noise conditions with varying degrees of time-varying fluctuations, many focused in the low frequency rumble region, were reproduced in an office-like setting. Thirty participants were asked to complete typing, grammatical reasoning, and math tasks plus subjective questionnaires, while being exposed for approximately one hour to each noise condition. Results show that the noise conditions with higher sound …