Friday, 26 November 2010
The device sandwiches a blob of a conducting polymer called PEDOT and a silicon diode between perpendicular wires.The key to the new technology was discovered by passing high current through PEDOT (Polyethylenedioxythiophene) which turns it into an insulator, rather like blowing a fuse .The polymer has two possible states- conductor and insulator, that form the one and zero, necessary to store digital data.However tuning the polymer into an insulator involves a permanent chemical change, meaning the memory can only be written once.
A new form of permanent computer memory which uses plastic and is much cheaper and faster than the existing silicon circuits was invented by Researchers at Princeton University working with Hewlett-Packard.This new memory technology is created by using a conducting plastic which has the potential to store a megabit of data in a millimeter-square device - 10 times denser than current magnetic memories.
This utilizes a previously unknown property of a cheap, transparent plastic called PEDOT - short for polyethylenedioxythiophene. The inventors say that data densities as high as a megabit per square millimeter can be possible. By stacking layers of memory, a cubic centimeter device could hold as much as a gigabyte and be cheap enough to compete with CDs and DVD.
This paper presents some modification in the robot i.e. to use the metal detector, infrared cameras for sensing in the very dim light or no light .temperature detector for detecting the human inside the building. In my paper I have used 10 mega pixel camera 360 rotation to get the clear cut view of the inside building .so this will help the army personnel to counter strike with the terrorist. There will be fewer casualties to army as well as human being. My motive for bringing this paper to you that there is a great scope of enhancement in the field of robotics for the security inside the country. The robot will also carry insurgency operation in country for countering terrorism. Human-Robot has recently received considerable attention in the academic community, in labs, in technology companies, and through the media. Because of this attention, it is desirable to present a survey of HR to serve as a tutorial to people outside the field and to promote discussion of a unified vision of HR within the field.
The unveiling of the Android platform on 5 November 2007 was announced with the founding of the Open Handset Alliance, a consortium of 34 hardware, software and telecom companies devoted to advancing open standards for mobile devices. When released in 2008, most of the Android platform will be made available under the Apache free-software and open-source license.
There are many variations on this scheme. It is possible to Phish for other information in additions to usernames and passwords such as credit card numbers, bank account numbers, social security numbers and mothers’ maiden names. Phishing presents direct risks through the use of stolen credentials and indirect risk to institutions that conduct business on line through erosion of customer confidence. The damage caused by phishing ranges from denial of access to e-mail to substantial financial loss.
This report also concerned with anti-phishing techniques. There are several different techniques to combat phishing, including legislation and technology created specifically to protect against phishing. No single technology will completely stop phishing. However a combination of good organization and practice, proper application of current technologies and improvements in security technology has the potential to drastically reduce the prevalence of phishing and the losses suffered from it. Anti-phishing software and computer programs are designed to prevent the occurrence of phishing and trespassing on confidential information. Anti-phishing software is designed to track websites and monitor activity; any suspicious behavior can be automatically reported and even reviewed as a report after a period of time.
This also includes detecting phishing attacks, how to prevent and avoid being scammed, how to react when you suspect or reveal a phishing attack and what you can do to help stop phishers.
Solid materials are ground or pulverized by way of hammer mills, attrition mills, granulators or other equipment. A smaller particle size is usually needed to enhance the further processing of the solid, as in mixing with other materials. A finer particle also helps in melting of rubber and plastics for molding. However, many materials are either very soft or very tough at room temperatures. By cooling to cryogenic temperatures with liquid nitrogen, these may be embrittled and easily fractured into small particles.
A scientifically controlled study using four herbs was conducted at Frontier Herbs in the Fall of 1996, comparing cryogenic grinding methods with normal grinding methods. The herbs tested included feverfew, goldenseal, valerian and echinacea. In all cases the cryogenically ground herb contained greater amounts of the constituents tested. Feverfew herb showed the greatest difference, with the cryogenically ground herb containing 21.8% higher levels of parthenolide, the primary active constituent. Valerian root showed an 18.7% increase in valerenic acid when cryogenically ground. Goldenseal root showed a 16.4% increase in berberine and 10.7% increase in hydrastine. Lastly, Echinacea purpurea root showed a 12.1% increase in total phenolic content in the cryogenically ground root. Test results were obtained by HPLC (high performance liquid chromatography) methods.
Cryogenic grinding was shown to significantly affect active constituent levels in herbs. Test results showed an average increase of 15.6% in constituents tested in four medicinal herbs when they were ground cryogenically. The range was 10.7% to 21.8%, indicating that some herbs are affected more than others by the temperatures at which they're ground.
They are usually made by ink jet printing process. In this method red green and blue polymer solutions are jetted into well defined areas on the substrate. This is because, PLEDs are soluble in common organic solvents like toluene and xylene .The film thickness uniformity is obtained by multi-passing (slow) is by heads with drive per nozzle technology .The pixels are controlled by using active or passive matrix.
It is a polymer that emits light when a voltage is applied to it. The structure comprises a thin-film of semiconducting polymer sandwiched between two electrodes (anode and cathode) as shown in fig.1. When electrons and holes are injected from the electrodes, the recombination of these charge carriers takes place, which leads to emission of light that escapes through glass substrate. The bandgap, i.e. energy difference between valence band and conduction band of the semiconducting polymer determines the wavelength (colour) of the emitted light.
The advantages include low cost, small size, no viewing angle restrictions, low power requirement, biodegradability etc. They are poised to replace LCDs used in laptops and CRTs used in desktop computers today.
Their future applications include flexible displays which can be folded, wearable displays with interactive features, camouflage etc.
A Static Synchronous Generator (SSG) is defined by IEEE as a self-commutated switching power converter supplied from from an appropriate electric energy source and operated to produce a set of adjustable multiphase voltages , which may be coupled to an ac power system for the purpose of exchanging independently controllable real and reactive power. When the active energy source (usually battery bank, Superconducting Magnetic Energy Storage etc) is dispensed with and replaced by a DC Capacitor which can not absorb or deliver real power except for short durations the SVG becomes a Static Synchronous Compensator (STATCOM) . STATCOM has no long term energy support in the DC Side and can not exchange real power with the ac system ; however it can exchange reactive power. Also , in principle, it can exchange harmonic power too. But when a STATCOM is designed to handle reactive power and harmonic currents together it gets a new name – Shunt Active Power Filter. So a STATCOM handles only fundamental reactive power exchange with the ac system.
STATCOMs are employed at distribution and transmission levels – though for different purposes. When a STATCOM is employed at the distribution level or at the load end for power factor improvement and voltage regulation alone it is called DSTATCOM. When it is used to do harmonic filtering in addition or exclusively it is called Active Power Filter. In the transmission system STATCOMs handle only fundamental reactive power and provide voltage support to buses. In addition STATCOMs in transmission system are also used to modulate bus voltages duting transient and dynamic disturbances in order to improve transient stability margins and to damp dynamic oscillations.
IEEE defines the second kind of Shunt Connected Controller called Static VAr Compensator (SVC) as a shunt connected static var generator or absorber whose output is adjusted to exchange capacitive or inductive current so as to maintain or control specific parameters of the electrical power system (typically bus voltage).Thyristor-switched or thyristor-controlled capacitors/inductors and combinations of such equipment with fixed capacitors and inductors come under this.This has been covered in an earlier lecture and this lecture focusses on STACOMs at distribution and transmission levels.
PWM Voltage Source Inverter based Static VAr Compensators (referred to as SVC here onwards) began to be considered a viable alternative to the existing passive shunt compensators and Thyristor Controlled Reactor (TCR ) based compensators from mid-eighties onwards. The disadvantages of capacitor/inductor compensation are well known. TCRs could overcome many of the disadvantages of passive compensators. However they suffered from two major disadvantages ;namely slow response to a VAr command and injection of considerable amount of harmonic currents into the power system which had to be cancelled by special transformers and filtered by heavy passive filters.
Conventionally ASIC's are being used where highly efficient systems are desired. The problem with ASIC is that once programmed it cannot be enhanced or changed, we have to get a
new ASIC for each modification. Other option is microprocessor based or dsp based applications. These can provide either programmability or efficiency. Now with stream processors we can achieve both simultaneously. A comparison of efficiency and programmability of Stream processors and other techniques are done. We will look into how efficiency and programmability is achieved in a stream processor. Also we will examine the
challenges faced by stream processor architecture.
The complex modern signal and image processing applications requires hundreds of GOPS (giga, or billions, of operations per second) with a power budget of a few watts, an efficiency of
about 100 GOPS/W (GOPS per watt), or 10 pJ/op (Pico Joules per operation). To meet this requirement current media processing applications use ASICs that are tailor made for a
particular application. Such processors require significant design efforts and are difficult to change when a new media processing application or algorithm evolve. The other alternative to meet the changing needs is to go for a dsp or microprocessor, which are highly flexible. But these do not provide the high efficiency needed by the application. Stream processors provide a solution to this problem by giving efficiency and programmability simultaneously. They achieve this by expressing the signal processing problems as signal flow graphs with streams flowing
between computational kernels. Stream processors have efficiency comparable to ASICs (200 GOPS/W), while being programmable in a high-level language. We will discuss how stream processor is achieves programmability and efficiency at the same time. Also we will look at the tools available for design of stream processing applications and challenges faced in this
approach to media processing.
The secret to functioning High Altitude Wind Power is efficient tether technology that reaches 15,000 feet in the air, far higher than birds will fly, but creating restricted airspace for planes and other aircraft.
The same materials used in the tethers that hold these balloons in place can also hold flying windmills in place; and with energy cable technology getting ever lighter and stronger .Flying windmills appear to be 90 percent more energy efficient in wind tunnel tests than their land-based counterparts; that is three times more efficiency due to simple yet constantly abundant and effective high altitude wind power, available only 15,000 feet in the air by way of clustered rotor craft kites tethered with existing anti-terrorist technologies like those used on the Mexican/American border radar balloons.
High Altitude Wind Power offers itself as a clean and more powerful source of power generation than anything available on-the-grid at present and if Sky WindPower Corp. has their way, FEG technology and flying windmills will take the lead of a more sustainable future within the decade.
Telephone companies have offered high bandwidth lines for many years. For the most part, the cost of these lines and the equipment needed to access them has limited their usefulness to large businesses. The lone exception has been ISDN (Integrated Services Digital Network) which has won over some residential customers. ISDN offers fast Internet access (128k) at a relatively low cost.
Here the solution is Powerline communications (or PLC). Powerline communications is a rapidly evolving market that utilizes electricity power lines for the high-speed transmission of data and voice services.
None of the available Internet access services offer the right balance of cost, convenience, and speed. Digital Powerline technology could change all that. It gives customers high speed Internet access through electrical networks. Lower costs are achieved because the service is implemented on standard electrical lines. The service is also convenient because it’s already in your home. Internet access through Digital Powerline would be at (at least) 1Mbps, 20 times faster than a standard phone/modem connection.
are supported by mechanical or air bearings. Usually, the long stroke actuator has a micrometer accuracy, while the submicron accuracy is achieved by the short-stroke actuator. To build a high-precision machine, as much disturbances as possible should be eliminated. Common sources of disturbances are vibrations, Coulomb and viscous friction in bearings, crosstalk of multiple cascaded actuators and cable slabs.A possibility to increase throughput, while maintaining accuracy is to use parallel processing, i.e. movement and positioning in parallel with inspection, calibration, assembling, scanning, etc. To meet the design requirements of high accuracy while improving performance, a new design approach is necessary, especially if vacuum operation is considered, which will be required for the next generation of lithography
machines. A lot of disturbance sources can be eliminated by integrating the cascaded long- and short-stroke actuator into one actuator system.
Since most long-stroke movements are in a plane, this can be done by a contactless planar actuator. A contactless planar actuator or planar motor is supported by magnetic bearings that levitate the actuator platform, while controlling all six DOF of the platform. Long-stroke linear
movement in 2D is also provided by the magnetic bearing while small translations in height and small rotations remain possible. Magnetic bearings can also operate in vacuum. Parallel processing requires power on the platform to drive the actuators on the platform. In order to remove as much disturbances as possible, the power transfer needs to be contactless, i.e. without wires from the ground to the platform. A coil topology and geometry for a contactless
energy transfer system is proposed for energy transfer to a planar moving platform. The platform is equipped with permanent magnets and is levitated and propelled by a matrix of coils, which are fixed to the ground. Such a planar actuator is currently under investigation at Eindhoven University of Technology. The aim of this research project is to transfer energy to the moving platform continuously and at every position in order to enhance the functionality of the platform, while maintaining the advantages of operating without contact and cables slabs
High-speed micro-turbines and mini-turbines play a significant role in the Distributed
Power Systems that provide dependable electric power close to the user. Several high-speed
turbo-generators manufactured by various corporations are now available in the 30 kW to 90 kW
range. These systems operate at speeds from 50000 RPM to 120000 RPM. The generator is
directly coupled to the turbine shaft. This obviates the need for a gearbox, helps reduce the size
of the generator, and lowers the cost of the overall system. The output power is electronically
processed and conditioned to provide constant voltage dc or multi-phase ac power at constant
Technology of micro-turbines is moving forward to address ratings above 100 kW due to
the growing demand for larger units. There is a tendency to use multiple units of the existing 30
to 90 kW packages to satisfy this demand for higher power capacity. However, use of turbogenerators
of higher ratings is likely to be beneficial to the user for the following reasons:
a) lower cost of investment per kW for purchase and installation
b) lower cost of maintenance because of reduced parts count
c) higher efficiency
d) safer operation.
At the present time most generators used with micro-turbines are based on permanent
magnet technology. It is the objective of this paper to compare alternatives to the PM generator
technology, and introduce induction generator technology as a more viable alternative in the
power range exceeding 100 kW. The approach in this paper is to present the concept in all its
dimensions including the issues of generator and controller design. The authors are currently
engaged in the development of the high-speed induction generator systems. Their experience in
the field of the technology forms the basis supporting the discussions in this paper.
|De-regulation of power market brings changes by creating an increase in competition among utilities. Minimizing the cost of maintenance and losses due to cable failures is a key to successful operation.|
Simulations demonstrate the possibility of applying condition-based maintenance for the entire service period of a cable system if maintenance cost could be lowered to a certain level.
The aging of power cables begins long before the cable actually fails. Preventing incipient failures developing into failures can greatly reduce loses. There are several external phenomena indicating undergoing aging problems, including partial discharges, hot spots, mechanical cracks and changes of insulation dielectric properties.
Most sensors currently used are cumbersome to move, complicated to use, or destructive to cables. In the presented project, non destructive miniature sensors capable of determining the status of power cable systems are developed and integrated into a monitoring system, including a video sensor for visual inspection, an infrared thermal sensor for detection of hot spots, an acoustic sensor for identifying partial discharge activities, and a fringing electric sensor for determining the aging status of insulating material.
Mobile monitoring can greatly reduce the maintenance cost and supply more accurate status of local cables over traditional monitoring techniques. The application range of condition-based maintenance can be expanded greatly with the aid of mobile monitoring.
A novel autonomous robot is developed A graphical user interface on the host computer is developed to enable motion control, sensor control and signal processing. Presented work demonstrates the use of mobile monitoring system for underground power cable systems to be viable and economically efficient...
Resilient Packet Ring (RPR).
The Vanadium Redox Flow Battery System(35)
Cellular Digital Packet Data (Cdpd)
Solid State Lighting
Fibre Optic Communication~
Web based remote device monitoring
Multi threading microprocessors
Evolution Of Embedded System
Cellular technologies and security.
Eye gaze human ? computer interface.
Electronic Road Pricing System~
Digit recognition using neural network
Ultra wide band technology.
Enhanced data rates for gsm evolution (edge).
Global Positioning System~
The mp3 standard.
Thermal infrared imaging technology
Extreme ultraviolet lithography*
Jseg-a method for unsupervised segmentation of color texture regions in images and video.
Multiple description coding.
The making of quantum dots.
Packet Cable Network(39)
Fpga offloads dsp?s.
Personal Area Network(40)
Wireless power transmission.
Voice recognition based on artificial neural networks.
Remote Accessible Virtual Instrumentation Control Lab(41)
Digital transmission content protection (dtcp)
Artificial immune system.
RTOS ? VXWORKS(42)
Resilient packet ring (rpr).
High performance Computing.
Packet Switching chips
Printable RFID circuits
Adaptive Multipath Detection(34)
Resilient Packet Ring (RPR).
The Vanadium Redox Flow Battery System(35)
Cellular Digital Packet Data (Cdpd)
Solid State Lighting
Fibre Optic Communication~
Web based remote device monitoring
Multi threading microprocessors
Evolution Of Embedded System
Cellular technologies and security.
Eye gaze human ? computer interface.
Electronic Road Pricing System~
Digit recognition using neural network
Ultra wide band technology.
Enhanced data rates for gsm evolution (edge).
Global Positioning System~
The mp3 standard.
Thermal infrared imaging technology
Extreme ultraviolet lithography*
The X-Internet, which boosts online user?s quality of experience and accelerates the number of connected devices. The once hottest technology ever evolved, 'Internet' is already being dubbed as 'dumb, boring and isolated' and the days of the World Wide Web are numbered. The web we know today will fade. It will be replaced by a new software paradigm. Some call it the X Internet; others The Semantic Web. The web we know is evolving. Gone will be the days of browser-based applications. The X-Internet will not be a new invention, but rather the evolution of today's Internet of static Web pages and cumbersome e-commerce mechanisms into a Net that relies on executable software code to deliver more interactive experiences.
As the Internet expands, two new waves of innovation comprising the X-Internet are already eclipsing the Web: an executable Net that greatly improves the online experience and an extended Net that connects the real world. An executable Net that supplants today's Web will move code to user PCs and cause devices to captivate consumers in ways static pages never could. The extended Internet is reshaping technology's role in business through Internet devices and applications which sense, analyze, and control data, therefore providing more real-time information than ever before about what is going on in the real world. The extended Internet will include the widespread adoption of real-world appliances, like air conditioners or car tires that communicate with owners or manufacturers via the Internet. X-Internet pushes connectivity past computers to other interactive devices, such as cell phones and televisions, and from there to a range of consumer products and applications.
Executable Internet applications use downloaded code like Java and XML to enhance the user experience with pop-up menus, pick lists, graphics and simple calculations. Unlike the existing Web wherein the browser pops up essentially static pages of information, the executable Internet will enable a conversation between two ?high IQ entities? on either side, with interactivity level rising to hitherto unforeseen levels as intelligent applications execute code on the user?s PC or other devices.
A tunable micro-electromechanical systems integrated inductor with a large-displacement electro-thermal actuator is discussed here. Based on a transformer configuration, the inductance of a spiral inductor is tuned by controlling the relative position of a magnetically coupled short-circuited loop. Theoretical studies are backed by a variety of fabricated and measured tunable inductors that show a 2 : 1 inductance tuning ratio over a wide frequency range of approximately 25 GHz. In addition, the maximum and minimum quality factors of the tunable inductor are measured to be 26 and 10 which is high compared to previous designs. They can considerably extend the tuning capabilities of critical reconfigurable circuits such as tunable impedance matching circuits, phase shifters voltage controlled oscillators, and low noise amplifiers.
MEMS are miniaturized device / array of devices combining mechanical and electrical components fabricated using IC batch production techniques. RF MEMS components are used for RF & MW and millimeter wave circuits. They are small devices of feature size of micron order. Fabricated by nano and micro technology. RF micro-electromechanical systems (MEMS) have been a rapidly growing field within the MEMS industry. In particular, a wide range of RF MEMS switches, varactors, and high- inductors have been developed and demonstrated over the last two decades. However, few solutions have been presented for obtaining tunable (or variable) MEMS inductors.
The approaches reported in the literature today for realizing a tunable MEMS inductor include: 1) control of the magnetic-core-material properties by changing the core permeability or displacing the core material; 2) usage of MEMS switches to digitally control the winding; 3) control of the mutual inductance between the turns of the inductor itself; and 4) control of the mutual inductance between the primary inductor and a separate short-circuited inductor.
Each of the demonstrated techniques has serious shortcomings that have not allowed RF designers to utilized tunable inductors in their designs. Changing the core permeability and consumes has resulted in very low quality factors significant amount of dc power (15-300 mW). In addition, movement of the core material requires large and complex actuators. Switchable inductors are limited by the number of switches utilized. Few switches result in a limited set of available values, while many switches drastically drop the quality of the inductor and result in large and narrowband circuits. Controlling the mutual inductance between the turns of the inductor itself has shown very limited inductance variations ( 18%). The fourth technique relies on coupling the inductor to be tuned (primary inductor) to a short-circuited inductor (secondary inductor) and controlling their coupling coefficient. In , both the primary and secondary inductors are implemented as single-turn loops. An electrostatic actuator changes the position of the short-circuited loop. This design exhibits a tuning ratio of 1.54:1 and requires very high electrostatic actuation voltages (150 V) and many complex fabrication steps. Besides this tuning ratio, no other information (e.g., quality factor and bandwidth) is given in . The reported results show high inductance tuning ratios of 2:1 and good quality factors of 15-21 for the entire tuning range. However, these are not integrated solutions because they rely on manual movement for reaching the required displacements. In addition, no information is provided in any of these papers on how the inductance and resistance of the short-circuited inductor affect the critical RF parameters of the tunable inductor. Consequently improved designs and implementation methodologies are needed for achieving simple structures with high and continuous tuning ranges, high quality factors, large bandwidth, and low occupied chip area.
Here, measured and theoretical results for an optimized tunable MEMS spiral inductor with an integrated large-displacement electro-thermal actuator are analyzed. The tunable MEMS inductor utilizes an integrated transformer configuration, which is composed of two magnetically coupled inductors. Tunability is achieved by varying the magnetic coupling coefficient (k) that is dominated by the distance between the two inductors. Results derived by a simple equivalent circuit, full-wave simulations, and measurements indicate that optimal RF performance requires minimized resistive losses on the secondary inductor.
Superconductivity is a phenomenon occurring in certain materials generally at very low temperatures, characterized by exactly zero electrical resistance and the exclusion of the interior magnetic field (the Meissner effect). It was discovered by Heike Kamerlingh Onnes in 1911. Applying the principle of Superconductivity in microwave and millimeter-wave (mm-wave) regions, components with superior performance can be fabricated. Major problem during the earlier days was the that the cryogenic burden has been perceived as too great compared to the performance advantage that could be realized. There were very specialized applications, such as low-noise microwave and mm-wave mixers and detectors, for the highly demanding radio astronomy applications where the performance gained was worth the effort and complexity. With the discovery of high temperature superconductors like copper oxide, rapid progress was made in the field of microwave superconductivity.
This topic describes the properties of superconductivity that can be exploited in microwave and mm-wave technologies to yield components with appreciable performance enhancement over conventional systems. Superconducting signal transmission lines can yield low attenuation, zero-dispersion signal transmission behavior for signals with frequency components less than about one tenth the superconducting energy gap. No other known microwave device technology can provide a similar behavior. Superconductors have also been used to make high speed digital circuits, josephsons junction and RF and microwave filters for mobile phone base stations.
Tuesday, 16 November 2010
Multiband Hysteresis Modulation and Switching Characterization for Sliding-Mode-Controlled Cascaded Multilevel Inverter(IEEE) 2010
. A Novel Three-Phase to Five-Phase Transformation Using a Special Transformer Connection 2010
. Reliability Evaluation ofB ulk Power Systems Incorporating UPFC (IEEE) 2010
. A 28-Pulse AC-DC ConverterB ased SMPS for Telecom Power Supply (B ePress) 2010
. A Real Time Power System Harmonic Estimator considering Fundamental Frequency Variations (B ePress) 2010
. Feasibility Study on Application of Voltage Source Inductive Filtering Converter in HVDC-Light Systems (IEEE) 2010
. Comparative study of induction motor efficiency optimization control strategy for electric vehicle 2010
. A Single-Phase Voltage-Controlled Grid-Connected Photovoltaic System With Power Quality Conditioner Functionality (IEEE) 2009
. Transient stability control of TCSC (IEEE) 2009
. A Control Methodology and Characterization of Dynamics for a Photovoltaic (PV) System Interfaced With a Distribution Network (IEEE) 2009
. Reduced rating VSC with a Zig-Zig transformer for current compensation in three phase four wire distribution system (IEEE) 2009
. UPQC signal detection algorithm based on PSO-Fuzzy (IEEE) 2009
. Power quality improvement in conventional electronic load controller for isolated Power Generation (IEEE) 2009
. Model predictive control of Unified power quality conditioner with control saturation (IEEE) 2009
. A fast-acting dc-link voltage controller for 3 phase DStatcom to compensate ac and dc loads (IEEE) 2009
. PMSM speed sensor less direct torque control based on EKF (IEEE) 2009
. Investigation of Sub Synchronous Resonance With VSC-B ased HVDC Transmission Systems (IEEE) 2009
. Operation and control of single phase micro-sources in a utility connected grid (IEEE) 2009
. MultiConverter Unified Power-Quality Conditioning System: MC- UPQC (IEEE) 2009
. The use of facts devices in distributed power systems-modeling ,interface case study(IJCE) 2009
. Development of Hybrid Active Power FilterB ased on the Adaptive Fuzzy Dividing Frequency-Control Method (IEEE) 2009
. A modular fuel cell modular DC-DC converter concept for High performance and Enhanced reliability (IEEE) 2009
. New multivariable dynamic model & robust control of a Voltage Source Converter for power system application (IEEE) 2009
. Dynamic Modeling and Simulation of Hybrid Power SystemsB ased on Renewable Energy (IEEE) 2009
. Double FrequencyB uck converter (IEEE) 2009
. Optimization of PI coefficients in DStatcom non linear controller for regulating dc voltage using Generic Algorithm (IEEE) 2009
. Optimal placement of shunt connected facts devices in a series compensated long transmission line (WCE) 2009
. Voltage flicker compensation using STATCOM (IEEE) 2009
. A variable speed, sensor less, induction motor using dc link measurement (IEEE) 2009
. Soft computing techniques for the control of an active power filter (IEEE) 2009
. Wide speed range estimation with parameter identification schemes of sensor less induction motors (IEEE) 2009
. Design and analysis of dynamic voltage restorer for deep voltage sag and harmonic compensation (IEEE) 2009
. Constant Power Control and Fault-Ride-Through Enhancement of DFIG Wind Turbines with Energy Storage (IEEE) 2009
. Modeling of FACTS DevicesB ased on SPWM VSCs (IEEE) 2009
. Design of a Modular UPQC Configuration Integrating a Components Economical Analysis (IEEE) 2009
. A New Proposal for Power Quality and Custom Power Improvement: OPEN UPQC (IEEE) 2009
. Space Vector Method for Voltage Dips and Swells Analysis (IEEE) 2009
. Analytical Modeling of a Square Wave Controlled Cascaded Multilevel STATCOM (IEEE) 2009
. Three-Phase Transformer Model Including Magnetic Hysteresis and Eddy Currents Effects (IEEE) 2009
. Output Feedback Control of Single-Phase UPQCB ased on a Novel Model (IEEE) 2009
. Harmonic Analysis and Improvement of a New Solid-State Fault Current Limiter (IEEE) 2009
.Multivariable Dynamic Model and Robust Control of a Voltage-Source Converter for Power System Applications (IEEE) 2009
. A Versatile Control Scheme for a Dynamic Voltage Restorer for 2009Power-Quality Improvement (IEEE)
. Study on a Novel Hybrid Active Power Filter Applied to a High- Voltage Grid (IEEE) 2009
. Seven-Level Shunt Active Power Filter for High-Power Drive Systems (IEEE) 2009
. Dynamic Voltage RestorerB ased on Flying Capacitor Multilevel Converters Operated by Repetitive Control (IEEE) 2009
. Sensor less Current Control of Three-Phase Inverter-B ased Distributed Generation (IEEE) 2009
. Optimum Space Vector Computation Technique for Direct Power Control (IEEE) 2009
. Wind Farms Modeling for Short-Circuit Level Calculations in Large Power Systems (IEEE) 2009
- Improving mains current quality for three phase three-switch buck-type PWM rectifiers – 2009
- Analysis and Design of Three-Phase Rectifier with Near-Sinusoidal Input Currents - 2009
- Single-Phase Matrix Converter Operating as Buck and Boost Rectifier - 2009
- Single-Phase Z-Source Buck-Boost Matrix Converter - 2009
- A Single-Stage Single-Phase Transformer-Less Doubly Grounded Grid-Connected PV Interface - 2009
- Hybrid Modeling and Simulation for the Boost Converter in Photovoltaic System - 2009
- Design and Control for Grid-connected Photovoltaic Inverter with LCL Filter - 2009
- Quasi-Z-Source Inverter for Photovoltaic Power Generation Systems - 2009
- Power Injection System for Photovoltaic Generation Plants with Active Filtering Capability - 2009
- The Electronic Ballast Using Class-E Rectifier with Tapped Inductor for Power Factor Correction - 2008
- A Novel Reference Compensation Current Strategy for Three-phase Three-level Unity PF Rectifier - 2009
- Single-Stage Soft-Switching Converter With Boost Type of Active Clamp for Wide Input Voltage Ranges - 2009
- Transformer less DC–DC Converters With High Step-Up Voltage Gain used for photovoltaic interface Application - 2009
- A Zero-Voltage-Switching Bidirectional DC–DC Converter With State Analysis and Soft- Switching-Oriented Design Consideration - 2009
- Soft-Switching Capability Analysis of a Dual Active Bridge Dc-Dc Converter - 2009
- Comparison of Control Methods for High-Voltage High-Power Three-Level Half-Bridge DC/DC Converters - 2009
- Design of High Voltage, High Power and High Frequency Transformer in LCC Resonant Converter – 2009
- LCC Resonant Converter Operating under Discontinuous Resonant Current Mode in High Voltage, High Power and High Frequency Applications - 2009
- Design of LCL-T Resonant Converter Including the Effect of Transformer Winding Capacitance – 2009
- A Non-isolated Bidirectional ZVS-PWM Active Clamped DC–DC Converter - 2009
- Analysis and implementation of Single-Switch Quasi-Resonant Converter - 2009
- Loss Analysis in Soft Switching Boost Converter using a single switch - 2009
- A Novel Soft Switching Flyback Converter with Synchronous Rectification - 2009 Zero-Current-Transition Bridgeless PFC Without Extra Voltage and Current Stress - 2009
- An Efficient Common-Mode Hybrid EMI Filter Used in Switch-mode Power Supply - 2009
- Active-Clamp ZVS Converter with Step-Up Voltage Conversion Ratio - 2009 Passive and Active Hybrid Integrated EMI Filters - 2009
- Modeling and design of a neutral point regulator for a three level diode clamped rectifier - 2009
- A novel three-phase PFC rectifier using a harmonic current injection method - 2009
- Single-Stage Fly back Converter for Constant Current Output LED Driver with Power Factor Correction - 2009
- A Modified SEPIC Converter for High Power Factor Rectifier and Universal-Input Voltage Applications - 2009
- A Compensation Technique for Smooth Transitions in Non-inverting Buck-Boost Converter - 2009
- A Novel Hybrid Operational Mode Wide Range Input ZVS Front-end Dc-Dc Converter Aiming at Optimized Overall Performance - 2009
- A Novel Low-Loss Modulation Strategy for High-Power Bidirectional Buck + Boost Converters - 2009
- A Novel ZVZCS LLC-Type Parallel Resonant Converter with A Separated Resonant Tank - 2009
- An Interleaved Boost Converter With Zero-Voltage Transition - 2009
- Analysis and implementation of Switched-capacitorized DC/DC Converters - 2009
- Analysis of Super-Lift Luo-Converters with Capacitor Voltage drop - 2009
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RESEQUENCING ANALYSIS OF STOP-AND-WAIT ARQ FOR PARALLEL MULTICHANNEL COMMUNICATIONS:--DOTNET--2009
ANALYSIS OF SHORTEST PATH ROUTING FOR LARGE MULTI-HOP WIRELESS NETWORKS:--DOTNET--2009
SECURE AND POLICY-COMPLIANT SOURCE ROUTING:--DOTNET--2009
MOBILITY MANAGEMENT APPROACHES FOR MOBILE IP NETWORKS: PERFORMANCE COMPARISON AND USE RECOMMENDATIONS:--JAVA--2009
MULTIPLE ROUTING CONFIGURATIONS FOR FAST IP NETWORK RECOVERY:--JAVA--2009
VIRUS SPREAD IN NETWORKS:--DOTNET--2009
MINING FILE DOWNLOADING TIME IN STOCHASTIC PEER TO PEER NETWORKS:--DOTNET--2008
RATE & DELAY GUARANTEES PROVIDED BY CLOSE PACKET SWITCHES WITH LOAD BALANCING:--JAVA--2008
GEOMETRIC APPROACH TO IMPROVING ACTIVE PACKET LOSS MEASUREMENT:--JAVA--2008
PERFORMANCE OF A SPECULATIVE TRANSMISSION SCHEME FOR SCHEDULING LATENCY REDUCTION:--JAVA-2008
RATE ALLOCATION & NETWORK LIFETIME PROBLEM FOR WIRELESS SENSOR NETWORKS:--DOTNET--2008
STATISTICAL TECHNIQUES FOR DETECTING TRAFFIC ANOMALIES THROUGH PACKET HEADER DATA:--DOTNET--2008
EFFICIENT ROUTING IN INTERMITTENTLY CONNECTED MOBILE NETWORKS: THE MULTIPLE COPY CASE:--DOTNET--2008
TWO TECHNIQUES FOR FAST COMPUTATION OF CONSTRAINED SHORTEST PATHS:--JAVA--2008
PROBABILISTIC PACKET MARKING FOR LARGE-SCALE IP TRACE BACK:--DOTNET
DUAL-LINK FAILURE RESILIENCY THROUGH BACKUP LINK MUTUAL EXCLUSION:--JAVA
A DISTRIBUTED DATABASE ARCHITECTURE FOR GLOBAL ROAMING IN NEXT-GENERATION MOBILE NETWORKS:--JAVA--2004
NETWORK BORDER PATROL: PREVENTING CONGESTION COLLAPSE AND PROMOTING FAIRNESS IN THE INTERNET:--JAVA--2004
Monday, 15 November 2010
Saturday, 13 November 2010
Navigation in the past has primarily relied on the use of a map, compass or other devices that must be interpreted visually. This project demonstrates the ability to navigate a user based on synthesized directional audio which allows the user to move to a known location without the use of a visual aid. The module uses a GPS, a digital compass, and an ATmega32 to generate sound based on the direction that the user must turn in order to face the correct direction.
The goal of this project was to create a device that allows a user to navigate to a predefined location though the use of auditory guidance.
The module uses GPS and a digital compass to determine at what angle the user hears the sound pulses. On initial startup the user selects from a number of predefined locations through the use of an LCD screen. Once the GPS has a lock, the module determines the bearing (angle from true North) that the user must travel to get to the destination. This angle is compared with the compass output and a sound is made based on which direction the user must turn to face the final location. The sound consists of short pulses that are delayed between the right and left side and modulated in amplitude to give the effect of direction.
One example implementation of this is self guided tours. A user could be guided though a predetermined course by following the sound of a recorded person's voice. In such a setting, if the user were to veer off course, the system would guide then guide the user back on course. Also, the direction of the guide's voice could be used to highlight the object of interest along the tour.
The project idea came after Dr. Land mentioned that you could create the effect of a sound coming from a location by properly spacing the left and right channel by a certain distance. It seemed like a good idea to use this for navigation. This principle is based in the way that humans naturally hear perceive direction. Sound will reach each ear at a slightly different time and volume. Based on those differences, humans are able to determine the direction of sound in the horizontal plane.
Figure 1 shows the high level design of system.
Figure 1: High level system design
The GPS communication uses a standard format (NMEA0283 V 2.2). These standards include GGA, GSV, GSA, and RMC. Of these, RMC (Recommended Minimum Navigation Information) is used in the final product for simplicity. Useful information from this protocol includes time, status, latitude, longitude, speed, and date. The other standards were used for development and debugging.
At this time there is no knowledge of existing patents, copyrights, and or trademarks that are relevant to this project. There are many devices that utilize GPS or a compass, but not together with this synthesized audio.
Having three group members made it nice as there were three distinct portions to the project, GPS, compass, and the synthesized audio. Each portion was developed on its own while keeping the others in mind and brought together at the end. For example, planning for the project included allocating resources between the sub functions including timers, registers, and ports.
Bringing together the three separate parts was tricky because of the timing budget. It was known that the GPS could only refresh at 1 Hz, but the sound and compass must be run much faster. We wanted the sound direction to change smoothly during the course of turning your head (faster than 1 Hz). Therefore, the GPS was allowed to run as fast as it could, depending on how many satellites were locked, and how many sound and compass functions were packed in between. This became tricky when multiple satellites were locked and the data stream from the GPS is continuous. The main structure of the program can be seen in Figure 2.
Figure 2: Software flow chart
The digital compass module used was a Hitachi HM55B from Parallax, mainly because we already had it before the project. The communication between this device was done with three wires (clock, data, and enable) in an SPI like fashion. The communication is based on the Basic Stamp function SHIFTIN/SHIFTOUT which is a two wire communication. The challenge was to implement this in C for the ATmega32. Timer1 was used to control the timing of the function and three GPIOs were used for the three controls. The compare interrupt was used to generate the clock and data as this allowed for the clock time to be set at fine resolution resulting in the fastest possible operation of the compass. The clock signal was generated at twice the data rate so that data could be clocked on both the rising and falling edge of the clock in attempt to keep this function as general as possible in case of future use for other projects. To get data, the ATmega32 pulses the enable bit high for two clock cycles, then sends 0b0000 on the shared data_in and data_out line. After another enable toggle, 0b1000 gets sent to the compass signifying a start measurement command. The ATmega32 then sends 0b1100 and reads in four bits waiting for the data conversion to be done. When the compass sends back 0b1100, the data is ready. The ATmega32 then clocks in 22 bits (11 for x value, and 11 for y value) of 2s complement data MSB first. After properly formatting the data to get the proper sign an atan(x/-y) is called to result in an angle. This is then converted from radian to degrees and compensated for the difference between true and magnetic North (subtracting 12 degrees here in Ithaca). The whole function takes 60mS to run, which was determined to be fast enough.
The PWMs from timers 0 and 2 are used to generate sound pulses. Each timer is set to operate in fast PWM mode with a prescaler of one, giving the PWMs a sample rate of 62500 sample/second. The overflow interrupts of each timer are used to update the OCR.
Initially, timer1 of the Atmega644 was used to generate two PWM waveforms. The idea was that since timer1 has two output compare registers, it should be able to generate two PWMs. Timer1 was able to generate two PWMs, but since OCR1A was used as the top value and the PWM waveforms were not unique, the outputs of OCR1A and OCR1B toggled whenever the overflow interrupt was triggered. Using two timers prevented the overflow interrupt from toggling both pulses and also allowed for one timer to be used as a time based when an interrupt was triggered.
The code used for direct digital synthesis was adopted from lab2 written by Dr. Land4. The DDS process consists of a sin function quantized into a 256 entry table and a ramp table to linearly increase or decrease wave amplitude. For this project, two more tables were used to represent the phase offset and amplitude of the wave at a given source degree. These tables are precomputed to prevent extra computation during execution.
The premise of delaying sounds arriving at each ear to simulate sound localization is based upon interaural time difference. By delaying the sound arriving at one ear by up to 660 microseconds, the sound will have the appearance of coming from the side of the leading sound pulse.5 For example, if the channel going to the left ear is delayed, then the listener will interpret the delay as a sound source that is closer to the person's right ear.
The phase offset table is used to represent the delay that is present at each degree. It was constructed to achieve no offset at a zero degree heading (the source is directly in front of the user) and maximum offset at 90 or 270 degrees. If the sound source is behind the user, then the channel of the ear furthest from the source will be fully delayed, encouraging the user to turn his or her head to better discriminate the location of the sound.
To make the sound direction more apparent, the amplitude of the delayed channel is also reduced. The sound is scaled according to a normal distribution so that full intensity is delivered when the user faces the source with a zero degree difference. As the user rotates away from the source direction, the amplitude of the PWM wave channel furthest from the source is reduced while the closer channel maintains full intensity.
We used interrupt driven serial communication over the USART to receive data from the GPS. The GPS outputs NMEA sentences approximately once a second at 4800 baud. An example of one packet of NMEA sentences is shown below.
There are several cases of redundant data between NMEA sentences and, for the purposes of this project; we only need one set of longitude and latitude. We decided to only read in the RMC (Recommended Minimum Content) sentence as a string and then extract the longitude and latitude from that string.
We use the USART character-ready interrupt which triggers as soon as a full character is received by the USART buffer. Once a character is ready in the USART buffer, the ISR writes the character to a string buffer and enters the state machine. The state machine successively checks for the characters that are expected to be seen at the beginning of the RMC sentence. If the program does not receive the expected header characters, it returns to the beginning of the state machine. If the input characters are ‘$’,’G’,’P’,’R’,’M’, and ’C’ in succession, program records the rest of the sentence as data. The sentence is terminated with the ‘\n’ character.
The data from the RMC sentence is written to a string buffer. Knowing the format of the RMC sentence, we use sscanf to extract the longitude and latitude. The longitude and latitude are sent in the format DDMM.MMMM where DD is in degrees and MM.MMMM is in seconds. We parse the data and recalculate the values in terms of degrees. It should also be noted that when writing to the string buffer, we ignored decimal points due to difficulties with sscanf reading in floating point numbers on the microcontroller. In order to compensate for this, we scaled the longitude and latitudes appropriately during the conversion into degrees and then radians.
We use the following equation to calculate the direction from the user’s current location to the final destination:
where lat1=current latitude, lat2=target latitude, and dlon=difference in current and target longitude.
In order for the interrupts to run at their desired speeds, we found that it was necessary that they not run at the same time. For this reason, we timed our system to first receive data from the GPS, and then run the compass data retrieval function and sound output as many times as possible before the next packet from the GPS.
We start the timing on the first packet received from the GPS and let the USART interrupt run until the entire RMC sentence is received. Once the RMC sentence is received, we turn off the USART interrupt in order to not interrupt on all of the characters of the other NMEA sentences. We then enable the interrupts for the compass function which takes approximately 60ms. As soon as the compass function ends, the sound function and its interrupts are run. The sound function will vary in length
based on its output, but it should never take more the 150ms. We then repeat the compass and sound functions again before turning the USART interrupt on, which will wait for the next RMC sentence. Running the compass and sound functions twice leaves enough time for the USART to be enabled before the next RMC sentence arrives.
The supporting hardware consisted of two active low pass filters used to buffer the audio. The wire routing was kept as compact as possible meaning that data lines ran close to the audio introducing a lot of noise. Using a custom PCB could remedy the problem, but was out of the scope of this project. A potentiometer was used on each channel to adjust the volume allowing ensuring equal volumes when pointing at the destination. Also, an LCD screen was used to select the initial destination. This was done with three buttons, screen up, screen down, and select. These were implemented active low with a 10k ohm pull up resistor and a 330 ohm resistor current protection.
It was found that overall the device worked as expected as multiple users were able to direct themselves to a location that they were unaware of. The rate at which the GPS acquires data is at best once a second and depends on the number of satellites locked. The sound and compass update twice a second. This is a little slower than desired, but is limited by the speed of the GPS and the computations of the bearing value. Three sound pulses might be possible if the math for the GPS (shown above) is changed from floating point to fixed point. A picture of the final device can be seen in Figure 3. LCD screen is located on the top of the device. This means that the user must take the device off to change location. This is acceptable as a compact unit was part of the project description.
Figure 3: Final Device
The accuracy of the device was found to be subjective to the user and their ability to recognize small differences in the sound pulses. However, it was found that in general the average user was able to resolve a direction to within +/- 10 degrees. The locations for the different data points were initially found with the use of a Motorola Droid and its internal GPS. This was found to be very accurate and provided a location to within a 3 meter radius.
Safety was not a big concern throughout the project, other than being alert and keeping your eyes open when navigating to the final destination. The project did not interface with other projects in a negative way, other than the occasional noise made while testing. The final project is a self contained unit that does not interfere with anything else.
This device could be used to solve a number of issues. As mentioned before, one could be used for self guided tours. Also, a boat operator might find it useful when navigating a boat at night time for far distance navigation. It can be understood that this would be useful for anyone needing navigation while not being able to look at a map. This could be useful for orienteering as you would not need to look at a map but could focus on the environment around you
Our initial goal was to guide a person by sound using data gathered from a GPS module. Before we started our project we acknowledged that the GPS module would have some uncertainty and there would be difficulty determining if the person was directly over the target location. Given the budget of this project we decided to sacrifice GPS accuracy in favor of staying within budget.
Our final prototype not only stayed within budget, but the GPS module performed to our expectations and the directional sound was sufficiently accurate. During the demo for this project, the professor, Dr. Land, was able to follow the sound pulses to a location about 5 minutes walking distance away. Dr. Land had no previous training with this device, but he was able to final the target location within 3 meters. Other curious bystanders were also able to identify the direction of target with very little direction.
If this project were to be improved, then a different GPS module capable of updating at 5Hz could be used instead of the 1Hz GPS used in the current prototype. This would increase the budget by about $25, but the code would also have to be altered to accommodate the more frequent updates. However more updates would require a faster clock speed, less frequent PWM pulses, or both. A different compass with a higher resolution than 6bits could also be used, but this would also increase the price of the project.
As mentioned in the introduction the GPS communication uses a standard format (NMEA0283 V 2.2). These standards include GGA, GSV, GSA, and RMC. Of these, RMC (Recommended Minimum Navigation Information) is used in the final product for simplicity. The other standards were used for development and debugging.
The code that was adapted from the 4760 website was from lab 2. This code consisted of using the PWM for DDS.
This project was designed to aid a person in guiding them towards a destination. It is not intended to be used to assist a person purely based upon sound. The navigation data used by this device is based upon GPS data, therefore obstacles are not taken into consideration and this device will not guide a person around any potential hazards.
The device does not produce an electrical shock or any other hazard that may cause harm to the person wearing it. The device is powered by a household 9V battery, therefore all safety considerations that apply to the proper handling of 9V batteries also apply to this device. The bread board is insulated from the user by the headphones. The only safety consideration that may affect the individual wearing this device is if the person wears it in the rain. Although the device is insulated from the user's head, the device does not have a cover to prevent moisture damage. Therefore this device should not be worn in any circumstance where it could be contaminated by moisture.
The data gathered by the GPS is only stored long enough to determine the direction that the user must travel. The data is not stored or tracked by any other means. Therefore, the privacy of the user is not violated by tracking the location of user.
Nick - GPS, Audio buffering/Filtering, general debug
Matt - Sound (PWM), LCD/Buttons, general debug
Garret -Compass, Combined three main programs together
Compass Module - http://www.parallax.com/Store/Microcontrollers/BASICStampModules/tabid/134/ProductID/98/List/1/Default.aspx?SortField=UnitCost,ProductName
GPS Module - http://www.parallax.com/StoreSearchResults/tabid/768/txtSearch/GPS/List/0/SortField/4/ProductID/560/Default.aspx
ATmega 32 - http://www.parallax.com/StoreSearchResults/tabid/768/txtSearch/GPS/List/0/SortField/4/ProductID/560/Default.aspx
ECE4760 - http://instruct1.cit.cornell.edu/courses/ee476/
Interaul Time Difference- http://en.wikipedia.org/wiki/Interaural_time_difference
In order to make the sound more pleasing to the ear and not nauseating, we had to keep the pulses consistently spaced in a consistent pattern. We did this by timing how long each function took and then spacing them out based on this. We initially tried to run the compass and sound one by one while the USART was running in the background the entire time. The overlapping interrupts caused unpredictable delays which were not only nauseating, but caused the data updates to be too slow for reasonable use.