2-bit Coding Research Articles

Proposal for 4‐to‐2 optical encoder based on photonic crystals

In this study, an all optical 4-to-2 encoder have been proposed which has four input and three output ports. The proposed structure can generate a 2-bit binary code considering which input port is active. For realising the proposed structure first the authors proposed and designed a BUFFER and an OR gate. Then combined these basic gates to realise the proposed encoder. The maximum switching delay and footprint for the proposed structure are about 200 fs and 880 μm2, respectively.

One-Bit Digital Coding Broadband Reflectarray Based on Fuzzy Phase Control

In this letter, we propose a new 1-bit digital coding broadband reflectarray design based on fuzzy phase control. To realize the coding reflectarray, two kinds of unit cells with 0 and π phase responses to mimic “0” and “1” elements for 1-bit digital coding are introduced. By coding the sequence of “0” and “1” elements, the electromagnetic waves can be manipulated to reach different functionalities. Theoretical rules of fuzzy phase control and coding are deduced and used to design a broadband reflectarray antenna. A prototype of a practical configuration is designed, fabricated, and measured to validate the theoretical analysis in X-band. Full-wave simulations and experiments clearly demonstrate the proposed antenna has the −1-dB bandwidth of 25% from 8.4 to 10.8 GHz. The measured results are in good agreement with the theoretical designs and simulated results, which verify the feasibility and correctness of the proposed approach in this letter.

Transmission-Type 2-Bit Programmable Metasurface for Single-Sensor and Single-Frequency Microwave Imaging.

The programmable and digital metamaterials or metasurfaces presented recently have huge potentials in designing real-time-controlled electromagnetic devices. Here, we propose the first transmission-type 2-bit programmable coding metasurface for single-sensor and single- frequency imaging in the microwave frequency. Compared with the existing single-sensor imagers composed of active spatial modulators with their units controlled independently, we introduce randomly programmable metasurface to transform the masks of modulators, in which their rows and columns are controlled simultaneously so that the complexity and cost of the imaging system can be reduced drastically. Different from the single-sensor approach using the frequency agility, the proposed imaging system makes use of variable modulators under single frequency, which can avoid the object dispersion. In order to realize the transmission-type 2-bit programmable metasurface, we propose a two-layer binary coding unit, which is convenient for changing the voltages in rows and columns to switch the diodes in the top and bottom layers, respectively. In our imaging measurements, we generate the random codes by computer to achieve different transmission patterns, which can support enough multiple modes to solve the inverse-scattering problem in the single-sensor imaging. Simple experimental results are presented in the microwave frequency, validating our new single-sensor and single-frequency imaging system.

In-Scratchpad Memory Replication

Scratchpad memories (SPMs) are widely employed in multicore embedded processors. Reliability is one of the major constraints in the embedded processor design, which is threatened with the increasing susceptibility of memory cells to multiple-bit upsets (MBUs) due to continuous technology down-scaling. This article proposes a low-cost and efficient data replication mechanism, called In-Scratchpad Memory Replication (ISMR), to correct MBUs in SPMs of multicore embedded processors. The main feature of ISMR is a smart controller, called Replication Management Unit (RMU), which is responsible for dynamically analyzing the activity of the SPM blocks at runtime and efficiently replicating the vulnerable SPM blocks into currently inactive SPM blocks. RMU exploits a 2-bit tag for each SPM block, where the value of each tag is determined by RMU according to the SPM access pattern. Accordingly, the proposed mechanism guarantees the replication of all vulnerable SPM blocks to provide error correction without decreasing the SPM utilization. To detect errors in SPM blocks, ISMR uses a 2-bit interleaved-parity code. As compared with the previous E-RAID 1 mechanism, the simulation results illustrate that for an 8-core embedded processor, the ISMR mechanism experiences 81% less energy consumption overhead and 48% less performance overhead.

Broadband diffusion of terahertz waves by multi-bit coding metasurfaces

The terahertz region is a special region of the electromagnetic spectrum that incorporates the advantages of both microwaves and infrared light waves. In the past decade, metamaterials with effective medium parameters or gradient phases have been studied to control terahertz waves and realize functional devices. Here, we present a new approach to manipulate terahertz waves by using coding metasurfaces that are composed of digital coding elements. We propose a general coding unit based on a Minkowski closed-loop particle that is capable of generating 1-bit coding (with two phase states of 0 and 180°), 2-bit coding (with four phase states of 0, 90°, 180°, and 270°), and multi-bit coding elements in the terahertz frequencies by using different geometric scales. We show that multi-bit coding metasurfaces have strong abilities to control terahertz waves by designing-specific coding sequences. As an application, we demonstrate a new scattering strategy of terahertz waves—broadband and wide-angle diffusion—using a 2-bit coding metasurface with a special coding design and verify it by both numerical simulations and experiments. The presented method opens a new route to reducing the scattering of terahertz waves. A team in China has demonstrated a new strategy for controlling terahertz waves by using ‘coding’ metasurfaces to attain broadband diffusion. Metamaterials have previously been used to control terahertz waves and develop functional devices. Now, Tie Jun Cui and co-workers have developed metasurfaces composed of one-, two- and three-bit digital coding elements based on Minkowski loops. They demonstrated their coding surfaces by showing that metasurfaces with appropriately designed coding sequences can be used to strongly manipulate terahertz waves. In particular, they realized broadband, wide-angle diffusion using a two-bit coding metasurface with a special design and obtained good agreement between the measured results and numerical simulations. The proposed method offers a new way to control scattering of terahertz waves and can be implemented using conventional lithography.

Abandoned Object Detection via Temporal Consistency Modeling and Back-Tracing Verification for Visual Surveillance

This paper presents an effective approach for detecting abandoned luggage in surveillance videos. We combine short- and long-term background models to extract foreground objects, where each pixel in an input image is classified as a 2-bit code. Subsequently, we introduce a framework to identify static foreground regions based on the temporal transition of code patterns, and to determine whether the candidate regions contain abandoned objects by analyzing the back-traced trajectories of luggage owners. The experimental results obtained based on video images from 2006 Performance Evaluation of Tracking and Surveillance and 2007 Advanced Video and Signal-based Surveillance databases show that the proposed approach is effective for detecting abandoned luggage, and that it outperforms previous methods.

Mixed-Level Response Surface Designs via a Hybrid Genetic Algorithm

Response surface methodology is widely used for developing, improving and optimizing processes in various fields. In this paper, we present a general algorithmic method for constructing 2 q1 4 q2 mixed-level designs in order to explore and optimize response surfaces with respect to D-efficiency, where the predictor variables are at two and four equally s paced levels, by utilizing a hybrid genetic algorithm. Emphasis is given on various properties that arise fro m the implementation of the genetic algorithm, such as using genetic operators as local optimizers and the representation of the four le vels of the design with a 2-bit Gray Code. We applied the genetic algorithm in several cases and the optimized mixed-level designs achieve good properties, thus demonstrating the efficiency of the proposed hybrid heuristic.

An analog integrated signal processing circuit for on-chip diffusion-based gas analysis

In diffusion-based gas analysis, the transient of gas diffusion process is recorded by a generic gas sensor to serve as a fingerprint for qualitative and quantitative analysis of gaseous samples. Following the acquisition of these specific signals, any standalone gas analyzer requires a pattern recognition system for pattern classification. The classic digital pattern recognition methods require computing hardware of adequate computational throughput. In this paper, we have followed a straightforward mathematical procedure to relate the signals to their associated target gases. We have shown that the procedure can be implemented by a set of analog functions. Based on the results, we have designed an analog integrated circuit, in 0.18 µm standard CMOS process, for processing the diffusion-based transient signals. The main circuit components are a low-pass filter, the differentiator, the feature extractor and an artificial neural network. The output of the circuit is a 2-bit binary code that specifies the target gas. The circuit successfully classified four alcoholic vapors by processing the experimentally obtained response patterns. The proposed signal processing circuit, the semiconductor gas sensor and the diffusion channel can all be implemented on a single substrate to fabricate an integrated micro gas analyzer.

English

Lossless image compression has long been recognised as an important need for several applications such as medical imaging, storage of critical IR image sequences, and remote sensing. In this paper, a simple, fast and easy to realisable-on-hardware lossless video compression algorithm is proposed that is well-suited for IR imageries. Context-based median predictor is used for prediction of reference pixels. Three neighboring pixels are used as context for prediction. Inter-frame coding is performed by encoding the redundant pixels in an efficient way, using 1-bit code. Finally, the arithmetic coder is used as entropy coding. The proposed algorithm is able to operate in image compression and video compression mode. The proposed Median Predictor based Lossless Video Compression (MPLVC) algorithm is compared with Joint Pictures Experts Group-Lossless (JPEG-LS) and Fast and Efficient Lossless Image Compression System (FELICS) for compression performance. The results demonstrate that proposed algorithm is superior in encoding rate with added advantage in simplicity and ease in realization on hardware.Defence Science Journal, 2009, 59(2), pp.183-188, DOI:http://dx.doi.org/10.14429/dsj.59.1507

バイオ・スニファを用いた化学情報システムに関する研究

A novel chemical code system was constructed with gas-phase biosensors (bio-sniffer) and a commercial inkjet printer. Two volatile chemicals, hydrogen peroxide (H2O2) and ethanol, were used for chemical code and printed by the inkjet printer. Each chemicals could be recognized by bio-sniffer fabricated with catalase and alcohol oxidase (AOD), respectively. Each bio-sniffer shoswed high selectivity due to the substrate specificity of the enzyme. Thus the combination of the sniffers was able to discriminate the inkjet printed 2-bit chemical code (4 patterns).

Digital Archiving Tomorrow: A Foresight

A large portion of the audio-visual heritage of our time is already stored on digital media or will be transferred in the near future onto such media. Unfortunately, current digital media are even less stable than traditional media and therefore periodic data migration every few years is mandatory. This approach is very cumbersome and risky. However novel concepts show a way out of this dead end situation. The underlying idea is that the digital data should not be passively migrated, but it should actively migrate itself. The idea is to develop future archiving concepts which are modeled on nature, i.e. on the living system. The genetic code (which is basically a 2-bit code) is the basic information for all biosystems, and it archives the information about species very successfully. Computer viruses and worms, despite being a severe nuisance, demonstrate that artificial live can be very successful and is very difficult to exterminate. Instead of having a maleficent payload, viruses and worms could be beneficial carriers of archived information and thus turned into positive “beneware”.

An Integrated Per-Channel PCM Encoder Based on Interpolation

A novel technique called interpolation has been used to integrate a per-channel PCM encoder in a standard digital circuit technology. This encoder converts voiceband analog signals to both an oversampled 1-bit code and uniform PCM with μ-law companding noise. The circuit comprises approximately 550 integrated injection logic gates together with a resistive digital-to-analog converter, a voltage reference, and a simple differential amplifier. The encoder is part of a full PCM codec chip set suitable for a broad range of voiceband telecommunication applications.

An integrated per-channel PCM encoder based on interpolation

Describes a novel technique called interpolation which has been used to integrate a per channel PCM encoder in a standard digital circuit technology. This encoder converts voiceband analog signals to both an oversampled 1-bit code and uniform PCM with /spl mu/-law companding noise. The circuit comprises approximately 550 integrated injection logic gates together with a resistive digital-to-analog converter, a voltage reference, and a simple differential amplifier. The encoder is part of a full PCM codec chip set suitable for a broad range of voiceband telecommunication applications.

Using Triangularly Weighted Interpolation to Get 13-Bit PCM from a Sigma-Delta Modulator

We present and analyze a method of interpolation that improves the amplitude resolution of an analog-to-digital converter. The technique requires feedback around a quantizer that operates at high speed and digital accumulation of its quantized values to provide a PCM output. We show that use of appropriate weights in the accumulation has important advantages for providing finer resoution, less spectral distortion, and white quantization noise. The theoretical discussion is supplemented by the report of a practical converter designed especially to show up the strengths and weaknesses of the technique. This converter comprises a sigma-delta modulator operating at 8 MHz and an accumulation of the 1-bit code with triangularly distributed weights. 13-bit resolution at 8 kwords/s is realized by periodically dumping the accumulation to the output. We present a practical method for overcoming a thresholding action that distorts low-amplitude input signals.