This paper describes a novel VLSI CMOS implementation of a self-compacting buffer (SCB) for the dynamically allocated multi-queue (DAMQ) switch architecture. The SCB dynamically allocates data regions within the outpu...
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(纸本)0889863512
This paper describes a novel VLSI CMOS implementation of a self-compacting buffer (SCB) for the dynamically allocated multi-queue (DAMQ) switch architecture. The SCB dynamically allocates data regions within the output buffer for different priority values of the data. The proposed implementation provides high performance solution to buffered communication switches that are required to interconnect networks. This performance comes from the implementation of the DAMQ, pipelining and novel circuitry. The major components of SCB are described in detail in this paper. The system has the capability of performing a read, a write or a simultaneous read/write operation per cycle.
Layered (LC) and multiple description coding (MDC) have been proposed as source coding techniques that are robust to channel errors for video transmission. In this paper, we investigate and study the error-resilience ...
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Layered (LC) and multiple description coding (MDC) have been proposed as source coding techniques that are robust to channel errors for video transmission. In this paper, we investigate and study the error-resilience capabilities of these two encoding techniques through extensive experimentation, and explore the environments where they perform best. Although some of our conclusions agree with those in the literature, we believe that this paper provides the most comprehensive performance comparison yet between LC and MDC.
Mechanical faults in induction motors can be detected by monitoring specific components in the stator current frequency spectrum. Previous work tested some mechanical conditions for the cases of no-load and full-load ...
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Mechanical faults in induction motors can be detected by monitoring specific components in the stator current frequency spectrum. Previous work tested some mechanical conditions for the cases of no-load and full-load conditions in small induction motors, assuming that the effect of load on the detection sch.me between these two conditions is linear. This paper presents an algorithm for detecting mechanical conditions in induction motors under any load condition using spectral analysis of the stator current. The proposed algorithm takes into account the load related abnormalities and resonance by classifying the load-levels into bins and calculating a baseline for each load bin.
This work identifies the relationships between the sizes of the oscillator's core MOSFETs and the phase noise in the 1/f2 region. Three packaged 1 GHz VCOs with the same LC tank circuit, but different gate lengths...
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This work identifies the relationships between the sizes of the oscillator's core MOSFETs and the phase noise in the 1/f2 region. Three packaged 1 GHz VCOs with the same LC tank circuit, but different gate lengths were designed and fabricated in a standard digital 0.6 μm CMOS technology. The minimum gate length (Lmin) of the core MOSFETs does not result in the minimum phase noise. Instead, the minimum phase noise occurs when the gate length is Lopt and Lopt = η · Lmin where η is a parameter that depends upon fabrication process and bias current. From measured results, the phase noise can be further decreased by 2 dBc/Hz at 600 kHz offset from 1 GHz center frequency by using the optimal sizes of the core MOSFETs.
A new approach to the adaptive mode transition control of unmanned aerial vehicles is proposed. The proposed architecture consists of three levels: the highest level is occupied by mission planning routines where info...
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A new approach to the adaptive mode transition control of unmanned aerial vehicles is proposed. The proposed architecture consists of three levels: the highest level is occupied by mission planning routines where information about way points the vehicle must follow is processed. The mid-level controller uses a trajectory-planning component to coordinate the task execution and provides set points for low-level stabilizing controllers. The adaptive mode transitioning control algorithm resides at the lowest level of the hierarchy consisting of a mode transitioning controller and the accompanying adaptation mechanism. An actual flight demonstration is planned for the near future as part of a DARPA sponsored research program to validate the control algorithms.
When designing a network simulation environment intended specifically for modeling large-scale topologies, a number of issues must be addressed by the simulator designer. Memory requirements for network simulation eng...
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When designing a network simulation environment intended specifically for modeling large-scale topologies, a number of issues must be addressed by the simulator designer. Memory requirements for network simulation engines can grow quadratically with the size of the simulated topology and can easily exceed available memory on modern workstations. The number of outstanding simulation events grows linearly with the number of packets in flight being modeled, and can lead to performance bottlenecks when managing a sorted event list of millions of events. Tracking the results of the simulation using a packet-level log file can result in excessive usage of disk space. We discuss the design of the Georgia Tech Network Simulator (GTNetS) with emphasis on how GTNetS addresses these issues. We give results from performance experiments showing the reduction in memory and event list size as a result of our design decisions.
We have designed and fabricated an addressable 4 × 4 array of micromirror capable of providing up to 90° of angular deflection. Each micromirror is comprised of a single-crystalline silicon mirror plate supp...
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We have designed and fabricated an addressable 4 × 4 array of micromirror capable of providing up to 90° of angular deflection. Each micromirror is comprised of a single-crystalline silicon mirror plate supported by aluminum springs, which provides an extremely flat reflective surface and a compliant spring material that enables the integration of the device into a limited area without mitigating its performance (i.e., total angular deflection). The device is fabricated using a combination of surface and bulk micromachining processes, such as elec.roplating, bulk wet etching and XeF2 etch processes. Selec.ive actuation is accomplished by the use of an elec.rostatic clamping force on each mirror plate. A mirror rotation angle of more than 80° can be obtained by applying an external magnetic field, and this angle can be further increased by the use of an elec.rostatic force. The designed structure can be used in microphotonic applications.
There are a number of applications in which it is desirable to be able to identify the technology, manufacturer, model, or even specific unit that was used to print a given document. Also, it may be desirable to embed...
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There are a number of applications in which it is desirable to be able to identify the technology, manufacturer, model, or even specific unit that was used to print a given document. Also, it may be desirable to embed additional information in the printed document, such as the date and time that it was printed. In previous work with laser elec.rophotographic printers, we developed strategies to reduce quasiperiodic banding artifacts that are characteristic of the specific print mechanism. The dominant process-direction spatial frequencies associated with these artifacts are determined by the parameters of the gear train in the print mechanism. Here we take a different view of these artifacts, treating them as a signature of the printer that can be identified by appropriate image analysis techniques. We refer to the characteristics of the native device as its intrinsic signature. By using the same strategies employed earlier to reduce the banding artifacts, we can amplify and modulate the banding to embed additional information, as discussed above. We refer to this as an extrinsic signature. In this paper, we describe our on-going research in this area. We present preliminary results from our effort to identify intrinsic printer signatures for a number of elec.rophotographic printers that are now on the market.
One of the main drawbacks of orthogonal frequency division multiplexing (OFDM) is the high peak-to-average power ratio (PAPR) of the transmitted OFDM signal. Partial transmit sequence (PTS) technique can improve the P...
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One of the main drawbacks of orthogonal frequency division multiplexing (OFDM) is the high peak-to-average power ratio (PAPR) of the transmitted OFDM signal. Partial transmit sequence (PTS) technique can improve the PAPR statistics of an OFDM signal. In the PTS technique, the data block to be transmitted is partitioned into disjoint sub-blocks and the sub-blocks are combined using phase factors to minimize PAPR. As ordinary PTS technique requires an exhaustive search over all combinations of allowed phase factors, the search complexity increases exponentially with the number of sub-blocks. In this paper, we propose a novel PTS technique with reduced complexity that achieves significant reduction in search complexity with little performance degradation.
Current sharing in interleaved converters is an essential issue for low-voltage, high-current Voltage Regulator Modules (VRMs). The most common method is to sense the average voltage across low-side switches to obtain...
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Current sharing in interleaved converters is an essential issue for low-voltage, high-current Voltage Regulator Modules (VRMs). The most common method is to sense the average voltage across low-side switches to obtain phase currents. In this paper, an instantaneous current sensing method is presented to observe instant load current and phase currents for multiphase buck converter. Since the load value is time varying, an adaptive control method is applied to estimate load changing. The proposed current observer can also be used for other topologies requiring current sensing. A digital observer is designed and implemented using a DSP controller.
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