Holography optical memory recorded with error correcting bits
NASA Astrophysics Data System (ADS)
Song, J. H.; Moon, I.; Lee, Y. H.
2014-06-01
A novel error correction method is proposed for volume holographic memory systems. In this method the information of two adjacent binary bits is recorded in the space between the two bits, which is used to correct the errors in the data bits. The new method is compared with (15, 5) Reed—Solomon code using the same redundancy of 200% as ours. It is shown that the new method achieves the similar bit error rate as the RS code.
Adaptation of bit error rate by coding
NASA Astrophysics Data System (ADS)
Marguinaud, A.; Sorton, G.
1984-07-01
The use of coding in spacecraft wideband communication to reduce power transmission, save bandwith, and lower antenna specifications was studied. The feasibility of a coder decoder functioning at a bit rate of 10 Mb/sec with a raw bit error rate (BER) of 0.001 and an output BER of 0.000000001 is demonstrated. A single block code protection, and two coding levels protection are examined. A single level protection BCH code with 5 errors correction capacity, 16% redundancy, and interleaving depth 4 giving a coded block of 1020 bits is simple to implement, but has BER = 0.000000007. A single level BCH code with 7 errors correction capacity and 12% redundancy meets specifications, but is more difficult to implement. Two level protection with 9% BCH outer and 10% BCH inner codes, both levels with 3 errors correction capacity and 8% redundancy for a coded block of 7050 bits is the most complex, but offers performance advantages.
Error correction using a bit redundancy
NASA Astrophysics Data System (ADS)
Schweikert, Robert; Dolainsky, Frank; Foerster, Hans Peter; Vinck, Adrianus Johannes
1989-11-01
Communication satellite systems are featuring increased use of channel coding methods for error correction. This paper describes a procedure which uses only one bit redundancy. Decoding this code is extremely simple and permits a significant reduction in requisite transmission capacity. The code is particularly useful where high transmission speeds are needed. The structure of the code is well suited for realizing decoder installations with an application-specific, integrated circuit. The VLSI design for a CMOS-gate-array for such a realization is discussed. Concatenated with other codes, the present code leads to significant hardware savings; an example concatenation with the Reed-Solomon code is shown.
Design of bit error rate tester based on a high speed bit and sequence synchronization
NASA Astrophysics Data System (ADS)
Wang, Xuanmin; Zhao, Xiangmo; Zhang, Lichuan; Zhang, Yinglong
2013-03-01
In traditional BER (Bit Error Rate) tester, bit synchronization applied digital PLL and sequence synchronization utilized sequence's correlation.It resulted in a low speed on bit and sequence synchronization. this paper came up new method to realize bit and sequence synchronization .which were Bit-edge-tracking method and Immitting-sequence method.The BER tester based on FPGA was designed.The functions of inserting error-bit and removing the false sequence synchronization were added. The results of Debuging and simulating display that the time to realize bit synchronization is less than a bit width, the lagged time of the tracking bit pulse is 1/8 of the code cycle,and there is only a M sequence's cycle to realize sequence synchronization.This new BER tester has many advantages,such as a short time to realize bit and sequence synchronization,no false sequence synchronization,testing the ability of the receiving port's error -correcting and a simple hareware.
Using Bit Errors To Diagnose Fiber-Optic Links
NASA Technical Reports Server (NTRS)
Bergman, L. A.; Hartmayer, R.; Marelid, S.
1989-01-01
Technique for diagnosis of fiber-optic digital communication link in local-area network of computers based on measurement of bit-error rates. Variable optical attenuator inserted in optical fiber to vary power of received signal. Bit-error rate depends on ratio of peak signal power to root-mean-square noise in receiver. For optimum measurements, one selects bit-error rate between 10 to negative 8th power and 10 to negative 4th power. Greater rates result in low accuracy in determination of signal-to-noise ratios, while lesser rates require impractically long measurement times.
Theoretical Accuracy for ESTL Bit Error Rate Tests
NASA Technical Reports Server (NTRS)
Lansdowne, Chatwin
1998-01-01
"Bit error rate" [BER] for the purposes of this paper is the fraction of binary bits which are inverted by passage through a communication system. BER can be measured for a block of sample bits by comparing a received block with the transmitted block and counting the erroneous bits. Bit Error Rate [BER] tests are the most common type of test used by the ESTL for evaluating system-level performance. The resolution of the test is obvious: the measurement cannot be resolved more finely than 1/N, the number of bits tested. The tolerance is not. This paper examines the measurement accuracy of the bit error rate test. It is intended that this information will be useful in analyzing data taken in the ESTL. This paper is divided into four sections and follows a logically ordered presentation, with results developed before they are evaluated. However, first-time readers will derive the greatest benefit from this paper by skipping the lengthy section devoted to analysis, and treating it as reference material. The analysis performed in this paper is based on a Probability Density Function [PDF] which is developed with greater detail in a past paper, Theoretical Accuracy for ESTL Probability of Acquisition Tests, EV4-98-609.
NASA Technical Reports Server (NTRS)
Ingels, F. M.; Schoggen, W. O.
1982-01-01
The design to achieve the required bit transition density for the Space Shuttle high rate multiplexes (HRM) data stream of the Space Laboratory Vehicle is reviewed. It contained a recommended circuit approach, specified the pseudo random (PN) sequence to be used and detailed the properties of the sequence. Calculations showing the probability of failing to meet the required transition density were included. A computer simulation of the data stream and PN cover sequence was provided. All worst case situations were simulated and the bit transition density exceeded that required. The Preliminary Design Review and the critical Design Review are documented. The Cover Sequence Generator (CSG) Encoder/Decoder design was constructed and demonstrated. The demonstrations were successful. All HRM and HRDM units incorporate the CSG encoder or CSG decoder as appropriate.
Achieving unequal error protection with convolutional codes
NASA Technical Reports Server (NTRS)
Mills, D. G.; Costello, D. J., Jr.; Palazzo, R., Jr.
1994-01-01
This paper examines the unequal error protection capabilities of convolutional codes. Both time-invariant and periodically time-varying convolutional encoders are examined. The effective free distance vector is defined and is shown to be useful in determining the unequal error protection (UEP) capabilities of convolutional codes. A modified transfer function is used to determine an upper bound on the bit error probabilities for individual input bit positions in a convolutional encoder. The bound is heavily dependent on the individual effective free distance of the input bit position. A bound relating two individual effective free distances is presented. The bound is a useful tool in determining the maximum possible disparity in individual effective free distances of encoders of specified rate and memory distribution. The unequal error protection capabilities of convolutional encoders of several rates and memory distributions are determined and discussed.
Measurements of Aperture Averaging on Bit-Error-Rate
NASA Technical Reports Server (NTRS)
Bastin, Gary L.; Andrews, Larry C.; Phillips, Ronald L.; Nelson, Richard A.; Ferrell, Bobby A.; Borbath, Michael R.; Galus, Darren J.; Chin, Peter G.; Harris, William G.; Marin, Jose A.; Burdge, Geoffrey L.; Wayne, David; Pescatore, Robert
2005-01-01
We report on measurements made at the Shuttle Landing Facility (SLF) runway at Kennedy Space Center of receiver aperture averaging effects on a propagating optical Gaussian beam wave over a propagation path of 1,000 in. A commercially available instrument with both transmit and receive apertures was used to transmit a modulated laser beam operating at 1550 nm through a transmit aperture of 2.54 cm. An identical model of the same instrument was used as a receiver with a single aperture that was varied in size up to 20 cm to measure the effect of receiver aperture averaging on Bit Error Rate. Simultaneous measurements were also made with a scintillometer instrument and local weather station instruments to characterize atmospheric conditions along the propagation path during the experiments.
Improving bit error rate through multipath differential demodulation
NASA Astrophysics Data System (ADS)
Lize, Yannick Keith; Christen, Louis; Nuccio, Scott; Willner, Alan E.; Kashyap, Raman
2007-02-01
Differential phase shift keyed transmission (DPSK) is currently under serious consideration as a deployable datamodulation format for high-capacity optical communication systems due mainly to its 3 dB OSNR advantage over intensity modulation. However DPSK OSNR requirements are still 3 dB higher than its coherent counter part, PSK. Some strategies have been proposed to reduce this penalty through multichip soft detection but the improvement is limited to 0.3dB at BER 10-3. Better performance is expected from other soft-detection schemes using feedback control but the implementation is not straight forward. We present here an optical multipath error correction technique for differentially encoded modulation formats such as differential-phase-shift-keying (DPSK) and differential polarization shift keying (DPolSK) for fiber-based and free-space communication. This multipath error correction method combines optical and electronic logic gates. The scheme can easily be implemented using commercially available interferometers and high speed logic gates and does not require any data overhead therefore does not affect the effective bandwidth of the transmitted data. It is not merely compatible but also complementary to error correction codes commonly used in optical transmission systems such as forward-error-correction (FEC). The technique consists of separating the demodulation at the receiver in multiple paths. Each path consists of a Mach-Zehnder interferometer with an integer bit delay and a different delay is used in each path. Some basic logical operations follow and the three paths are compared using a simple majority vote algorithm. Receiver sensitivity is improved by 0.35 dB in simulations and 1.5 dB experimentally at BER of 10-3.
Design and verification of a bit error rate tester in Altera FPGA for optical link developments
NASA Astrophysics Data System (ADS)
Cao, T.; Chang, J.; Gong, D.; Liu, C.; Liu, T.; Xiang, A.; Ye, J.
2010-12-01
This paper presents a custom bit error rate (BER) tester implementation in an Altera Stratix II GX signal integrity development kit. This BER tester deploys a parallel to serial pseudo random bit sequence (PRBS) generator, a bit and link status error detector and an error logging FIFO. The auto-correlation pattern enables receiver synchronization without specifying protocol at the physical layer. The error logging FIFO records both bit error data and link operation events. The tester's BER and data acquisition functions are utilized in a proton test of a 5 Gbps serializer. Experimental and data analysis results are discussed.
Bit-to-bit error dependence in direct-sequence spread-spectrum multiple-access packet radio systems
NASA Astrophysics Data System (ADS)
Morrow, Robert K., Jr.
1988-05-01
Slotted direct-sequence spread-spectrum multiple-access (DS/SSMA) packet broadcasting systems with random signature sequences are analyzed within the framework of the lower three layers of the International Standards Organization Reference Model of Open Systems Interconnection. At the physical layer, we show that a widely-used Gaussian approximation (which we call the Standard Gaussian Approximation) for the probability of data bit error in a chip and phase asynchronous system is accurate only when there are a large number of simultaneous users on the channel; otherwise, this approximation can be optimistic by several orders of magnitude. For interfering signals with fixed delays and phases relative to the desired signal, however, the Standard Gaussian Approximation is quite accurate for any number of simultaneous users. To obtain a closer approximation to the probability of data bit error for an asynchronous system, we introduce the Improved Gaussian Approximation, which involves finding the distribution of the multiple-access interference variance over all possible delay and phase values and then taking a Gaussian approximation over the support of the distribution and averaging the results. To accurately analyze packet performance at the data link layer, we first use the theory of moment spaces to gain insight on the effect of bit-to-bit error dependence caused by the constant relative delays and (possibly) phases of the interfering signals over the duration of a desired packet.
Bit-Error-Rate Performance of a Gigabit Ethernet O-CDMA Technology Demonstrator (TD)
Hernandez, V J; Mendez, A J; Bennett, C V; Lennon, W J
2004-07-09
An O-CDMA TD based on 2-D (wavelength/time) codes is described, with bit-error-rate (BER) and eye-diagram measurements given for eight users. Simulations indicate that the TD can support 32 asynchronous users.
Shuttle bit rate synchronizer. [signal to noise ratios and error analysis
NASA Technical Reports Server (NTRS)
Huey, D. C.; Fultz, G. L.
1974-01-01
A shuttle bit rate synchronizer brassboard unit was designed, fabricated, and tested, which meets or exceeds the contractual specifications. The bit rate synchronizer operates at signal-to-noise ratios (in a bit rate bandwidth) down to -5 dB while exhibiting less than 0.6 dB bit error rate degradation. The mean acquisition time was measured to be less than 2 seconds. The synchronizer is designed around a digital data transition tracking loop whose phase and data detectors are integrate-and-dump filters matched to the Manchester encoded bits specified. It meets the reliability (no adjustments or tweaking) and versatility (multiple bit rates) of the shuttle S-band communication system through an implementation which is all digital after the initial stage of analog AGC and A/D conversion.
Reducing Measurement Error in Student Achievement Estimation
ERIC Educational Resources Information Center
Battauz, Michela; Bellio, Ruggero; Gori, Enrico
2008-01-01
The achievement level is a variable measured with error, that can be estimated by means of the Rasch model. Teacher grades also measure the achievement level but they are expressed on a different scale. This paper proposes a method for combining these two scores to obtain a synthetic measure of the achievement level based on the theory developed…
Bit-Error Ratio Testing of Xilinx FPGAs Using Pseudo-Random Binary Sequences
NASA Astrophysics Data System (ADS)
Goers, Andy
2008-10-01
With RHIC collision rates reaching orders of a MHz in pp reactions, it is vital that detector electronics are able to process the massive influx of data received every second. Much of this data processing is done by field programmable gate arrays (FPGAs). However, with any experimental setup, one must know the limitations of the apparatus. High speed electronics often see bit errors due to attenuation or simply from hardware failures. Bit errors in detector electronics can show up as bad data and even ``fake'' particles, so it is important to know how often these bit errors occur. Pseudo-random binary sequences (PRBS) are often used to test high speed electronics' bit-error ratios (BER), or errant bits per bits received. A PRBS is generated using polynomials creating a seemingly random sequence of binary numbers. A BER can be measured by sending out and receiving a known PRBS and checking for errors in the received sequence. I will present results of BER testing of gigabit transceiver protocols on Xilinx Virtex 5 LXT50T and LXT110T FPGAs for PHENIX detector electronics upgrades.
Bit error rate investigation of spin-transfer-switched magnetic tunnel junctions
NASA Astrophysics Data System (ADS)
Wang, Zihui; Zhou, Yuchen; Zhang, Jing; Huai, Yiming
2012-10-01
A method is developed to enable a fast bit error rate (BER) characterization of spin-transfer-torque magnetic random access memory magnetic tunnel junction (MTJ) cells without integrating with complementary metal-oxide semiconductor circuit. By utilizing the reflected signal from the devices under test, the measurement setup allows a fast measurement of bit error rates at >106, writing events per second. It is further shown that this method provides a time domain capability to examine the MTJ resistance states during a switching event, which can assist write error analysis in great detail. BER of a set of spin-transfer-torque MTJ cells has been evaluated by using this method, and bit error free operation (down to 10-8) for optimized in-plane MTJ cells has been demonstrated.
NASA Technical Reports Server (NTRS)
Ingels, F.; Schoggen, W. O.
1981-01-01
Several methods for increasing bit transition densities in a data stream are summarized, discussed in detail, and compared against constraints imposed by the 2 MHz data link of the space shuttle high rate multiplexer unit. These methods include use of alternate pulse code modulation waveforms, data stream modification by insertion, alternate bit inversion, differential encoding, error encoding, and use of bit scramblers. The psuedo-random cover sequence generator was chosen for application to the 2 MHz data link of the space shuttle high rate multiplexer unit. This method is fully analyzed and a design implementation proposed.
Cascade Error Projection with Low Bit Weight Quantization for High Order Correlation Data
NASA Technical Reports Server (NTRS)
Duong, Tuan A.; Daud, Taher
1998-01-01
In this paper, we reinvestigate the solution for chaotic time series prediction problem using neural network approach. The nature of this problem is such that the data sequences are never repeated, but they are rather in chaotic region. However, these data sequences are correlated between past, present, and future data in high order. We use Cascade Error Projection (CEP) learning algorithm to capture the high order correlation between past and present data to predict a future data using limited weight quantization constraints. This will help to predict a future information that will provide us better estimation in time for intelligent control system. In our earlier work, it has been shown that CEP can sufficiently learn 5-8 bit parity problem with 4- or more bits, and color segmentation problem with 7- or more bits of weight quantization. In this paper, we demonstrate that chaotic time series can be learned and generalized well with as low as 4-bit weight quantization using round-off and truncation techniques. The results show that generalization feature will suffer less as more bit weight quantization is available and error surfaces with the round-off technique are more symmetric around zero than error surfaces with the truncation technique. This study suggests that CEP is an implementable learning technique for hardware consideration.
Bit Error Probability for Maximum Likelihood Decoding of Linear Block Codes
NASA Technical Reports Server (NTRS)
Lin, Shu; Fossorier, Marc P. C.; Rhee, Dojun
1996-01-01
In this paper, the bit error probability P(sub b) for maximum likelihood decoding of binary linear codes is investigated. The contribution of each information bit to P(sub b) is considered. For randomly generated codes, it is shown that the conventional approximation at high SNR P(sub b) is approximately equal to (d(sub H)/N)P(sub s), where P(sub s) represents the block error probability, holds for systematic encoding only. Also systematic encoding provides the minimum P(sub b) when the inverse mapping corresponding to the generator matrix of the code is used to retrieve the information sequence. The bit error performances corresponding to other generator matrix forms are also evaluated. Although derived for codes with a generator matrix randomly generated, these results are shown to provide good approximations for codes used in practice. Finally, for decoding methods which require a generator matrix with a particular structure such as trellis decoding or algebraic-based soft decision decoding, equivalent schemes that reduce the bit error probability are discussed.
NASA Technical Reports Server (NTRS)
Ingels, F.; Schoggen, W. O.
1981-01-01
The various methods of high bit transition density encoding are presented, their relative performance is compared in so far as error propagation characteristics, transition properties and system constraints are concerned. A computer simulation of the system using the specific PN code recommended, is included.
Optimal GSTDN/TDRSS bit error rate evaluation using limited sample sizes
NASA Technical Reports Server (NTRS)
Coffey, R. E.; Lawrence, G. M.; Stuart, J. R.
1982-01-01
Statistical studies of telemetry errors were made on data from the Solar Mesosphere Explorer (SME). Examination of frame sync words, as received at the ground station, indicated a wide spread of Bit Error Rates (BER) among stations. A study of the distribution of errors per station pass, however, showed that there was a tendency for the station software to add an even number of spurious errors to the count. A count of wild points in science data, rejecting drop-outs and other system errors, yielded an average random BER of 3.1 x 10 to the -6 with 99% confidence limits of 2.6 and 3.8 x 10 to the -6. The system errors are typically 5 to 100 times more frequent than the truly random errors.
Detecting bit-flip errors in a logical qubit using stabilizer measurements
Ristè, D.; Poletto, S.; Huang, M.-Z.; Bruno, A.; Vesterinen, V.; Saira, O.-P.; DiCarlo, L.
2015-01-01
Quantum data are susceptible to decoherence induced by the environment and to errors in the hardware processing it. A future fault-tolerant quantum computer will use quantum error correction to actively protect against both. In the smallest error correction codes, the information in one logical qubit is encoded in a two-dimensional subspace of a larger Hilbert space of multiple physical qubits. For each code, a set of non-demolition multi-qubit measurements, termed stabilizers, can discretize and signal physical qubit errors without collapsing the encoded information. Here using a five-qubit superconducting processor, we realize the two parity measurements comprising the stabilizers of the three-qubit repetition code protecting one logical qubit from physical bit-flip errors. While increased physical qubit coherence times and shorter quantum error correction blocks are required to actively safeguard the quantum information, this demonstration is a critical step towards larger codes based on multiple parity measurements. PMID:25923318
Multi-bits error detection and fast recovery in RISC cores
NASA Astrophysics Data System (ADS)
Jing, Wang; Xing, Yang; Yuanfu, Zhao; Weigong, Zhang; Jiao, Shen; Keni, Qiu
2015-11-01
The particles-induced soft errors are a major threat to the reliability of microprocessors. Even worse, multi-bits upsets (MBUs) are ever-increased due to the rapidly shrinking feature size of the IC on a chip. Several architecture-level mechanisms have been proposed to protect microprocessors from soft errors, such as dual and triple modular redundancies (DMR and TMR). However, most of them are inefficient to combat the growing multi-bits errors or cannot well balance the critical paths delay, area and power penalty. This paper proposes a novel architecture, self-recovery dual-pipeline (SRDP), to effectively provide soft error detection and recovery with low cost for general RISC structures. We focus on the following three aspects. First, an advanced DMR pipeline is devised to detect soft error, especially MBU. Second, SEU/MBU errors can be located by enhancing self-checking logic into pipelines stage registers. Third, a recovery scheme is proposed with a recovery cost of 1 or 5 clock cycles. Our evaluation of a prototype implementation exhibits that the SRDP can successfully detect particle-induced soft errors up to 100% and recovery is nearly 95%, the other 5% will inter a specific trap.
Characterization of multiple-bit errors from single-ion tracks in integrated circuits
NASA Technical Reports Server (NTRS)
Zoutendyk, J. A.; Edmonds, L. D.; Smith, L. S.
1989-01-01
The spread of charge induced by an ion track in an integrated circuit and its subsequent collection at sensitive nodal junctions can cause multiple-bit errors. The authors have experimentally and analytically investigated this phenomenon using a 256-kb dynamic random-access memory (DRAM). The effects of different charge-transport mechanisms are illustrated, and two classes of ion-track multiple-bit error clusters are identified. It is demonstrated that ion tracks that hit a junction can affect the lateral spread of charge, depending on the nature of the pull-up load on the junction being hit. Ion tracks that do not hit a junction allow the nearly uninhibited lateral spread of charge.
Error tolerance of topological codes with independent bit-flip and measurement errors
NASA Astrophysics Data System (ADS)
Andrist, Ruben S.; Katzgraber, Helmut G.; Bombin, H.; Martin-Delgado, M. A.
2016-07-01
Topological quantum error correction codes are currently among the most promising candidates for efficiently dealing with the decoherence effects inherently present in quantum devices. Numerically, their theoretical error threshold can be calculated by mapping the underlying quantum problem to a related classical statistical-mechanical spin system with quenched disorder. Here, we present results for the general fault-tolerant regime, where we consider both qubit and measurement errors. However, unlike in previous studies, here we vary the strength of the different error sources independently. Our results highlight peculiar differences between toric and color codes. This study complements previous results published in New J. Phys. 13, 083006 (2011), 10.1088/1367-2630/13/8/083006.
Bit error rate performance of Image Processing Facility high density tape recorders
NASA Technical Reports Server (NTRS)
Heffner, P.
1981-01-01
The Image Processing Facility at the NASA/Goddard Space Flight Center uses High Density Tape Recorders (HDTR's) to transfer high volume image data and ancillary information from one system to another. For ancillary information, it is required that very low bit error rates (BER's) accompany the transfers. The facility processes about 10 to the 11th bits of image data per day from many sensors, involving 15 independent processing systems requiring the use of HDTR's. When acquired, the 16 HDTR's offered state-of-the-art performance of 1 x 10 to the -6th BER as specified. The BER requirement was later upgraded in two steps: (1) incorporating data randomizing circuitry to yield a BER of 2 x 10 to the -7th and (2) further modifying to include a bit error correction capability to attain a BER of 2 x 10 to the -9th. The total improvement factor was 500 to 1. Attention is given here to the background, technical approach, and final results of these modifications. Also discussed are the format of the data recorded by the HDTR, the magnetic tape format, the magnetic tape dropout characteristics as experienced in the Image Processing Facility, the head life history, and the reliability of the HDTR's.
Design and Verification of an FPGA-based Bit Error Rate Tester
NASA Astrophysics Data System (ADS)
Xiang, Annie; Gong, Datao; Hou, Suen; Liu, Chonghan; Liang, Futian; Liu, Tiankuan; Su, Da-Shung; Teng, Ping-Kun; Ye, Jingbo
Bit error rate (BER) is the principle measure of performance of a data transmission link. With the integration of high-speed transceivers inside a field programmable gate array (FPGA), the BER testing can now be handled by transceiver-enabled FPGA hardware. This provides a cheaper alternative to dedicated table-top equipment and offers the flexibility of test customization and data analysis. This paper presents a BER tester implementation based on the Altera Stratix II GX and IV GT development boards. The architecture of the tester is described. Lab test results and field test data analysis are discussed. The Stratix II GX tester operates at up to 5 Gbps and the Stratix IV GT tester operates at up to 10 Gbps, both in 4 duplex channels. The tester deploys a pseudo random bit sequence (PRBS) generator and detector, a transceiver controller, and an error logger. It also includes a computer interface for data acquisition and user configuration. The tester's functionality was validated and its performance characterized in a point-to-point serial optical link setup. BER vs. optical receiver sensitivity was measured to emulate stressed link conditions. The Stratix II GX tester was also used in a proton test on a custom designed serializer chip to record and analyse radiation-induced errors.
High-speed communication detector characterization by bit error rate measurements
NASA Technical Reports Server (NTRS)
Green, S. I.
1978-01-01
Performance data taken on several candidate high data rate laser communications photodetectors is presented. Measurements of bit error rate versus signal level were made in both a 1064 nm system at 400 Mbps and a 532 nm system at 500 Mbps. RCA silicon avalanche photodiodes are superior at 1064 nm, but the Rockwell hybrid 3-5 avalanche photodiode preamplifiers offer potentially superior performance. Varian dynamic crossed field photomultipliers are superior at 532 nm, however, the RCA silicon avalanche photodiode is a close contender.
Digitally modulated bit error rate measurement system for microwave component evaluation
NASA Technical Reports Server (NTRS)
Shalkhauser, Mary Jo W.; Budinger, James M.
1989-01-01
The NASA Lewis Research Center has developed a unique capability for evaluation of the microwave components of a digital communication system. This digitally modulated bit-error-rate (BER) measurement system (DMBERMS) features a continuous data digital BER test set, a data processor, a serial minimum shift keying (SMSK) modem, noise generation, and computer automation. Application of the DMBERMS has provided useful information for the evaluation of existing microwave components and of design goals for future components. The design and applications of this system for digitally modulated BER measurements are discussed.
NASA Technical Reports Server (NTRS)
Kerczewski, Robert J.; Fujikawa, Gene; Svoboda, James S.; Lizanich, Paul J.
1990-01-01
Satellite communications links are subject to distortions which result in an amplitude versus frequency response which deviates from the ideal flat response. Such distortions result from propagation effects such as multipath fading and scintillation and from transponder and ground terminal hardware imperfections. Bit-error rate (BER) degradation resulting from several types of amplitude response distortions were measured. Additional tests measured the amount of BER improvement obtained by flattening the amplitude response of a distorted laboratory simulated satellite channel. The results of these experiments are presented.
Bit error rate testing of fiber optic data links for MMIC-based phased array antennas
NASA Technical Reports Server (NTRS)
Shalkhauser, K. A.; Kunath, R. R.; Daryoush, A. S.
1990-01-01
The measured bit-error-rate (BER) performance of a fiber optic data link to be used in satellite communications systems is presented and discussed. In the testing, the link was measured for its ability to carry high burst rate, serial-minimum shift keyed (SMSK) digital data similar to those used in actual space communications systems. The fiber optic data link, as part of a dual-segment injection-locked RF fiber optic link system, offers a means to distribute these signals to the many radiating elements of a phased array antenna. Test procedures, experimental arrangements, and test results are presented.
Bit error rate tester using fast parallel generation of linear recurring sequences
Pierson, Lyndon G.; Witzke, Edward L.; Maestas, Joseph H.
2003-05-06
A fast method for generating linear recurring sequences by parallel linear recurring sequence generators (LRSGs) with a feedback circuit optimized to balance minimum propagation delay against maximal sequence period. Parallel generation of linear recurring sequences requires decimating the sequence (creating small contiguous sections of the sequence in each LRSG). A companion matrix form is selected depending on whether the LFSR is right-shifting or left-shifting. The companion matrix is completed by selecting a primitive irreducible polynomial with 1's most closely grouped in a corner of the companion matrix. A decimation matrix is created by raising the companion matrix to the (n*k).sup.th power, where k is the number of parallel LRSGs and n is the number of bits to be generated at a time by each LRSG. Companion matrices with 1's closely grouped in a corner will yield sparse decimation matrices. A feedback circuit comprised of XOR logic gates implements the decimation matrix in hardware. Sparse decimation matrices can be implemented with minimum number of XOR gates, and therefore a minimum propagation delay through the feedback circuit. The LRSG of the invention is particularly well suited to use as a bit error rate tester on high speed communication lines because it permits the receiver to synchronize to the transmitted pattern within 2n bits.
Achieving high bit rate logical stochastic resonance in a bistable system by adjusting parameters
NASA Astrophysics Data System (ADS)
Yang, Ding-Xin; Gu, Feng-Shou; Feng, Guo-Jin; Yang, Yong-Min; Ball, Andrew
2015-11-01
The phenomenon of logical stochastic resonance (LSR) in a nonlinear bistable system is demonstrated by numerical simulations and experiments. However, the bit rates of the logical signals are relatively low and not suitable for practical applications. First, we examine the responses of the bistable system with fixed parameters to different bit rate logic input signals, showing that an arbitrary high bit rate LSR in a bistable system cannot be achieved. Then, a normalized transform of the LSR bistable system is introduced through a kind of variable substitution. Based on the transform, it is found that LSR for arbitrary high bit rate logic signals in a bistable system can be achieved by adjusting the parameters of the system, setting bias value and amplifying the amplitudes of logic input signals and noise properly. Finally, the desired OR and AND logic outputs to high bit rate logic inputs in a bistable system are obtained by numerical simulations. The study might provide higher feasibility of LSR in practical engineering applications. Project supported by the National Natural Science Foundation of China (Grant No. 51379526).
Influence of wave-front aberrations on bit error rate in inter-satellite laser communications
NASA Astrophysics Data System (ADS)
Yang, Yuqiang; Han, Qiqi; Tan, Liying; Ma, Jing; Yu, Siyuan; Yan, Zhibin; Yu, Jianjie; Zhao, Sheng
2011-06-01
We derive the bit error rate (BER) of inter-satellite laser communication (lasercom) links with on-off-keying systems in the presence of both wave-front aberrations and pointing error, but without considering the noise of the detector. Wave-front aberrations induced by receiver terminal have no influence on the BER, while wave-front aberrations induced by transmitter terminal will increase the BER. The BER depends on the area S which is truncated out by the threshold intensity of the detector (such as APD) on the intensity function in the receiver plane, and changes with root mean square (RMS) of wave-front aberrations. Numerical results show that the BER rises with the increasing of RMS value. The influences of Astigmatism, Coma, Curvature and Spherical aberration on the BER are compared. This work can benefit the design of lasercom system.
Noise and measurement errors in a practical two-state quantum bit commitment protocol
NASA Astrophysics Data System (ADS)
Loura, Ricardo; Almeida, Álvaro J.; André, Paulo S.; Pinto, Armando N.; Mateus, Paulo; Paunković, Nikola
2014-05-01
We present a two-state practical quantum bit commitment protocol, the security of which is based on the current technological limitations, namely the nonexistence of either stable long-term quantum memories or nondemolition measurements. For an optical realization of the protocol, we model the errors, which occur due to the noise and equipment (source, fibers, and detectors) imperfections, accumulated during emission, transmission, and measurement of photons. The optical part is modeled as a combination of a depolarizing channel (white noise), unitary evolution (e.g., systematic rotation of the polarization axis of photons), and two other basis-dependent channels, namely the phase- and bit-flip channels. We analyze quantitatively the effects of noise using two common information-theoretic measures of probability distribution distinguishability: the fidelity and the relative entropy. In particular, we discuss the optimal cheating strategy and show that it is always advantageous for a cheating agent to add some amount of white noise—the particular effect not being present in standard quantum security protocols. We also analyze the protocol's security when the use of (im)perfect nondemolition measurements and noisy or bounded quantum memories is allowed. Finally, we discuss errors occurring due to a finite detector efficiency, dark counts, and imperfect single-photon sources, and we show that the effects are the same as those of standard quantum cryptography.
NASA Astrophysics Data System (ADS)
Kim, Do-Hyung; Cho, Janghyun; Moon, Hyungbae; Jeon, Sungbin; Park, No-Cheol; Yang, Hyunseok; Park, Kyoung-Su; Park, Young-Pil
2013-09-01
Optimized image restoration is suggested in angular-multiplexing-page-based holographic data storage. To improve the bit error rate (BER), an extended high frequency enhancement filter is recalculated from the point spread function (PSF) and Gaussian mask as the image restoration filter. Using the extended image restoration filter, the proposed system reduces the number of processing steps compared with the image upscaling method and provides better performance in BER and SNR. Numerical simulations and experiments were performed to verify the proposed method. The proposed system exhibited a marked improvement in BER from 0.02 to 0.002 for a Nyquist factor of 1.1, and from 0.006 to 0 for a Nyquist factor of 1.2. Moreover, more than 3 times faster performance in calculation time was achieved compared with image restoration with PSF upscaling owing to the reductions in the number of system process and calculation load.
SITE project. Phase 1: Continuous data bit-error-rate testing
NASA Astrophysics Data System (ADS)
Fujikawa, Gene; Kerczewski, Robert J.
1992-09-01
The Systems Integration, Test, and Evaluation (SITE) Project at NASA LeRC encompasses a number of research and technology areas of satellite communications systems. Phase 1 of this project established a complete satellite link simulator system. The evaluation of proof-of-concept microwave devices, radiofrequency (RF) and bit-error-rate (BER) testing of hardware, testing of remote airlinks, and other tests were performed as part of this first testing phase. This final report covers the test results produced in phase 1 of the SITE Project. The data presented include 20-GHz high-power-amplifier testing, 30-GHz low-noise-receiver testing, amplitude equalization, transponder baseline testing, switch matrix tests, and continuous-wave and modulated interference tests. The report also presents the methods used to measure the RF and BER performance of the complete system. Correlations of the RF and BER data are summarized to note the effects of the RF responses on the BER.
SITE project. Phase 1: Continuous data bit-error-rate testing
NASA Technical Reports Server (NTRS)
Fujikawa, Gene; Kerczewski, Robert J.
1992-01-01
The Systems Integration, Test, and Evaluation (SITE) Project at NASA LeRC encompasses a number of research and technology areas of satellite communications systems. Phase 1 of this project established a complete satellite link simulator system. The evaluation of proof-of-concept microwave devices, radiofrequency (RF) and bit-error-rate (BER) testing of hardware, testing of remote airlinks, and other tests were performed as part of this first testing phase. This final report covers the test results produced in phase 1 of the SITE Project. The data presented include 20-GHz high-power-amplifier testing, 30-GHz low-noise-receiver testing, amplitude equalization, transponder baseline testing, switch matrix tests, and continuous-wave and modulated interference tests. The report also presents the methods used to measure the RF and BER performance of the complete system. Correlations of the RF and BER data are summarized to note the effects of the RF responses on the BER.
NASA Astrophysics Data System (ADS)
Schmidt-Nielsen, Astrid
1987-08-01
The recognition of ICAO spelling alphabet words (ALFA, BRAVO, CHARLIE, etc.) is compared with diagnostic rhyme test (DRT) scores for the same conditions. The voice conditions include unprocessed speech; speech processed through the DOD standard linear-predictive-coding algorithm operating at 2400 bit/s with random error rates of 0, 2, 5, 8, and 12 percent; and speech processed through an 800-bit/s pattern-matching algorithm. The results suggest that, with distinctive vocabularies, word intelligibility can be expected to remain high even when DRT scores fall into the poor range. However, once the DRT scores fall below 75 percent, the intelligibility can be expected to fall off rapidly; at DRT scores below 50, the recognition of a distinctive vocabulary should also fall below 50 percent.
NASA Technical Reports Server (NTRS)
Marshall, Paul; Carts, Marty; Campbell, Art; Reed, Robert; Ladbury, Ray; Seidleck, Christina; Currie, Steve; Riggs, Pam; Fritz, Karl; Randall, Barb
2004-01-01
A viewgraph presentation that reviews recent SiGe bit error test data for different commercially available high speed SiGe BiCMOS chips that were subjected to various levels of heavy ion and proton radiation. Results for the tested chips at different operating speeds are displayed in line graphs.
Chen, Yu-Ta; Ou-Yang, Mang; Lee, Cheng-Chung
2012-06-01
Although widely recognized as a promising candidate for the next generation of data storage devices, holographic data storage systems (HDSS) incur adverse effects such as noise, misalignment, and aberration. Therefore, based on the structural similarity (SSIM) concept, this work presents a more accurate locating approach than the gray level weighting method (GLWM). Three case studies demonstrate the effectiveness of the proposed approach. Case 1 focuses on achieving a high performance of a Fourier lens in HDSS, Cases 2 and 3 replace the Fourier lens with a normal lens to decrease the quality of the HDSS, and Case 3 demonstrates the feasibility of a defocus system in the worst-case scenario. Moreover, the bit error rate (BER) is evaluated in several average matrices extended from the located position. Experimental results demonstrate that the proposed SSIM method renders a more accurate centering and a lower BER, lower BER of 2 dB than those of the GLWM in Cases 1 and 2, and BER of 1.5 dB in Case 3. PMID:22695607
Bit-error-rate testing of high-power 30-GHz traveling wave tubes for ground-terminal applications
NASA Technical Reports Server (NTRS)
Shalkhauser, Kurt A.; Fujikawa, Gene
1986-01-01
Tests were conducted at NASA Lewis to measure the bit-error-rate performance of two 30 GHz, 200 W, coupled-cavity traveling wave tubes (TWTs). The transmission effects of each TWT were investigated on a band-limited, 220 Mb/sec SMSK signal. The tests relied on the use of a recently developed digital simulation and evaluation system constructed at Lewis as part of the 30/20 GHz technology development program. The approach taken to test the 30 GHz tubes is described and the resultant test data are discussed. A description of the bit-error-rate measurement system and the adaptations needed to facilitate TWT testing are also presented.
Bounds of the bit error probability of a linear cyclic code over GF(2 exp l) and its extended code
NASA Technical Reports Server (NTRS)
Cheng, Unjeng; Huth, Gaylord K.
1988-01-01
An upper bound on the bit-error probability (BEP) of a linear cyclic code over GF(2 exp l) with hard-decision (HD) maximum-likelihood (ML) decoding on memoryless symmetric channels is derived. Performance results are presented for Reed-Solomon codes on GF(32), GF(64), and GF(128). Also, a union upper bound on the BEP of a linear cyclic code with either HD or soft-decision (SD) ML decoding is developed, as well as the corresponding bounds for the extended code of a linear cyclic code. Using these bounds, which are tight at low bit error rate, the performance advantage of SD and HD ML over bounded-distance decoding is established.
Bit-error-rate testing of high-power 30-GHz traveling-wave tubes for ground-terminal applications
NASA Technical Reports Server (NTRS)
Shalkhauser, Kurt A.
1987-01-01
Tests were conducted at NASA Lewis to measure the bit-error-rate performance of two 30-GHz 200-W coupled-cavity traveling-wave tubes (TWTs). The transmission effects of each TWT on a band-limited 220-Mbit/s SMSK signal were investigated. The tests relied on the use of a recently developed digital simulation and evaluation system constructed at Lewis as part of the 30/20-GHz technology development program. This paper describes the approach taken to test the 30-GHz tubes and discusses the test data. A description of the bit-error-rate measurement system and the adaptations needed to facilitate TWT testing are also presented.
NASA Technical Reports Server (NTRS)
Warner, Joseph D.; Theofylaktos, Onoufrios
2012-01-01
A method of determining the bit error rate (BER) of a digital circuit from the measurement of the analog S-parameters of the circuit has been developed. The method is based on the measurement of the noise and the standard deviation of the noise in the S-parameters. Once the standard deviation and the mean of the S-parameters are known, the BER of the circuit can be calculated using the normal Gaussian function.
NASA Astrophysics Data System (ADS)
Li, Mi; Li, Bowen; Zhang, Xuping; Song, Yuejiang; Liu, Jia; Tu, Guojie
2015-08-01
Space optical communication technique is attracting increasingly more attention because it owns advantages such as high security and great communication quality compared with microwave communication. As the space optical communication develops, people have already achieved the communication at data rate of Gb/s currently. The next generation for space optical system have goal of the higher data rate of 40Gb/s. However, the traditional optical communication system cannot satisfy it when the data rate of system is at such high extent. This paper will introduce ground optical communication system of 40Gb/s data rate as to achieve the space optical communication at high data rate. Speaking of the data rate of 40Gb/s, we must apply waveguide modulator to modulate the optical signal and magnify this signal by laser amplifier. Moreover, the more sensitive avalanche photodiode (APD) will be as the detector to increase the communication quality. Based on communication system above, we analyze character of communication quality in downlink of space optical communication system when data rate is at the level of 40Gb/s. The bit error rate (BER) performance, an important factor to justify communication quality, versus some parameter ratios is discussed. From results, there exists optimum ratio of gain factor and divergence angle, which shows the best BER performance. We can also increase ratio of receiving diameter and divergence angle for better communication quality. These results can be helpful to comprehend the character of optical communication system at high data rate and contribute to the system design.
Practical scheme to share a secret key through a quantum channel with a 27.6% bit error rate
Chau, H.F.
2002-12-01
A secret key shared through quantum key distribution between two cooperative players is secure against any eavesdropping attack allowed by the laws of physics. Yet, such a key can be established only when the quantum channel error rate due to eavesdropping or imperfect apparatus is low. Here, a practical quantum key distribution scheme by making use of an adaptive privacy amplification procedure with two-way classical communication is reported. Then, it is proven that the scheme generates a secret key whenever the bit error rate of the quantum channel is less than 0.5-0.1{radical}(5){approx_equal}27.6%, thereby making it the most error resistant scheme known to date.
Practical scheme to share a secret key through a quantum channel with a 27.6% bit error rate
NASA Astrophysics Data System (ADS)
Chau, H. F.
2002-12-01
A secret key shared through quantum key distribution between two cooperative players is secure against any eavesdropping attack allowed by the laws of physics. Yet, such a key can be established only when the quantum channel error rate due to eavesdropping or imperfect apparatus is low. Here, a practical quantum key distribution scheme by making use of an adaptive privacy amplification procedure with two-way classical communication is reported. Then, it is proven that the scheme generates a secret key whenever the bit error rate of the quantum channel is less than 0.5-0.1(5)≈27.6%, thereby making it the most error resistant scheme known to date.
Accurate Time-Dependent Traveling-Wave Tube Model Developed for Computational Bit-Error-Rate Testing
NASA Technical Reports Server (NTRS)
Kory, Carol L.
2001-01-01
prohibitively expensive, as it would require manufacturing numerous amplifiers, in addition to acquiring the required digital hardware. As an alternative, the time-domain TWT interaction model developed here provides the capability to establish a computational test bench where ISI or bit error rate can be simulated as a function of TWT operating parameters and component geometries. Intermodulation products, harmonic generation, and backward waves can also be monitored with the model for similar correlations. The advancements in computational capabilities and corresponding potential improvements in TWT performance may prove to be the enabling technologies for realizing unprecedented data rates for near real time transmission of the increasingly larger volumes of data demanded by planned commercial and Government satellite communications applications. This work is in support of the Cross Enterprise Technology Development Program in Headquarters' Advanced Technology & Mission Studies Division and the Air Force Office of Scientific Research Small Business Technology Transfer programs.
Alpha Dithering to Correct Low-Opacity 8 Bit Compositing Errors
Williams, P L; Frank, R J; LaMar, E C
2003-03-31
This paper describes and analyzes a dithering technique for accurately specifying small values of opacity ({alpha}) that would normally not be possible because of the limited number of bits available in the alpha channel of graphics hardware. This dithering technique addresses problems related to compositing numerous low-opacity semitransparent polygons to create volumetric effects with graphics hardware. The paper also describes the causes and a possible solution to artifacts that arise from parallel or distributed volume rendering using bricking on multiple GPU's.
Bit-error-rate testing of fiber optic data links for MMIC-based phased array antennas
NASA Technical Reports Server (NTRS)
Shalkhauser, K. A.; Kunath, R. R.; Daryoush, A. S.
1990-01-01
The measured bit-error-rate (BER) performance of a fiber optic data link to be used in satellite communications systems is presented and discussed. In the testing, the link was measured for its ability to carry high burst rate, serial-minimum shift keyed (SMSK) digital data similar to those used in actual space communications systems. The fiber optic data link, as part of a dual-segment injection-locked RF fiber optic link system, offers a means to distribute these signals to the many radiating elements of a phased array antenna. Test procedures, experimental arrangements, and test results are presented.
NASA Astrophysics Data System (ADS)
Nazrul Islam, A. K. M.; Majumder, S. P.
2015-06-01
Analysis is carried out to evaluate the conditional bit error rate conditioned on a given value of pointing error for a Free Space Optical (FSO) link with multiple receivers using Equal Gain Combining (EGC). The probability density function (pdf) of output signal to noise ratio (SNR) is also derived in presence of pointing error with EGC. The average BER of a SISO and SIMO FSO links are analytically evaluated by averaging the conditional BER over the pdf of the output SNR. The BER performance results are evaluated for several values of pointing jitter parameters and number of IM/DD receivers. The results show that, the FSO system suffers significant power penalty due to pointing error and can be reduced by increasing in the number of receivers at a given value of pointing error. The improvement of receiver sensitivity over SISO is about 4 dB and 9 dB when the number of photodetector is 2 and 4 at a BER of 10-10. It is also noticed that, system with receive diversity can tolerate higher value of pointing error at a given BER and transmit power.
Real-time minimal bit error probability decoding of convolutional codes
NASA Technical Reports Server (NTRS)
Lee, L. N.
1973-01-01
A recursive procedure is derived for decoding of rate R=1/n binary convolutional codes which minimizes the probability of the individual decoding decisions for each information bit subject to the constraint that the decoding delay be limited to Delta branches. This new decoding algorithm is similar to, but somewhat more complex than, the Viterbi decoding algorithm. A real-time, i.e. fixed decoding delay, version of the Viterbi algorithm is also developed and used for comparison to the new algorithm on simulated channels. It is shown that the new algorithm offers advantages over Viterbi decoding in soft-decision applications such as in the inner coding system for concatenated coding.
NASA Astrophysics Data System (ADS)
Andrist, Ruben S.; Wootton, James R.; Katzgraber, Helmut G.
2015-04-01
Current approaches for building quantum computing devices focus on two-level quantum systems which nicely mimic the concept of a classical bit, albeit enhanced with additional quantum properties. However, rather than artificially limiting the number of states to two, the use of d -level quantum systems (qudits) could provide advantages for quantum information processing. Among other merits, it has recently been shown that multilevel quantum systems can offer increased stability to external disturbances. In this study we demonstrate that topological quantum memories built from qudits, also known as Abelian quantum double models, exhibit a substantially increased resilience to noise. That is, even when taking into account the multitude of errors possible for multilevel quantum systems, topological quantum error-correction codes employing qudits can sustain a larger error rate than their two-level counterparts. In particular, we find strong numerical evidence that the thresholds of these error-correction codes are given by the hashing bound. Considering the significantly increased error thresholds attained, this might well outweigh the added complexity of engineering and controlling higher-dimensional quantum systems.
Extending the lifetime of a quantum bit with error correction in superconducting circuits.
Ofek, Nissim; Petrenko, Andrei; Heeres, Reinier; Reinhold, Philip; Leghtas, Zaki; Vlastakis, Brian; Liu, Yehan; Frunzio, Luigi; Girvin, S M; Jiang, L; Mirrahimi, Mazyar; Devoret, M H; Schoelkopf, R J
2016-08-25
Quantum error correction (QEC) can overcome the errors experienced by qubits and is therefore an essential component of a future quantum computer. To implement QEC, a qubit is redundantly encoded in a higher-dimensional space using quantum states with carefully tailored symmetry properties. Projective measurements of these parity-type observables provide error syndrome information, with which errors can be corrected via simple operations. The 'break-even' point of QEC--at which the lifetime of a qubit exceeds the lifetime of the constituents of the system--has so far remained out of reach. Although previous works have demonstrated elements of QEC, they primarily illustrate the signatures or scaling properties of QEC codes rather than test the capacity of the system to preserve a qubit over time. Here we demonstrate a QEC system that reaches the break-even point by suppressing the natural errors due to energy loss for a qubit logically encoded in superpositions of Schrödinger-cat states of a superconducting resonator. We implement a full QEC protocol by using real-time feedback to encode, monitor naturally occurring errors, decode and correct. As measured by full process tomography, without any post-selection, the corrected qubit lifetime is 320 microseconds, which is longer than the lifetime of any of the parts of the system: 20 times longer than the lifetime of the transmon, about 2.2 times longer than the lifetime of an uncorrected logical encoding and about 1.1 longer than the lifetime of the best physical qubit (the |0〉f and |1〉f Fock states of the resonator). Our results illustrate the benefit of using hardware-efficient qubit encodings rather than traditional QEC schemes. Furthermore, they advance the field of experimental error correction from confirming basic concepts to exploring the metrics that drive system performance and the challenges in realizing a fault-tolerant system. PMID:27437573
NASA Astrophysics Data System (ADS)
Suess, D.; Fuger, M.; Abert, C.; Bruckner, F.; Vogler, C.
2016-06-01
We report two effects that lead to a significant reduction of the switching field distribution in exchange spring media. The first effect relies on a subtle mechanism of the interplay between exchange coupling between soft and hard layers and anisotropy that allows significant reduction of the switching field distribution in exchange spring media. This effect reduces the switching field distribution by about 30% compared to single-phase media. A second effect is that due to the improved thermal stability of exchange spring media over single-phase media, the jitter due to thermal fluctuation is significantly smaller for exchange spring media than for single-phase media. The influence of this overall improved switching field distribution on the transition jitter in granular recording and the bit error rate in bit-patterned magnetic recording is discussed. The transition jitter in granular recording for a distribution of Khard values of 3% in the hard layer, taking into account thermal fluctuations during recording, is estimated to be a = 0.78 nm, which is similar to the best reported calculated jitter in optimized heat-assisted recording media.
Suess, D; Fuger, M; Abert, C; Bruckner, F; Vogler, C
2016-01-01
We report two effects that lead to a significant reduction of the switching field distribution in exchange spring media. The first effect relies on a subtle mechanism of the interplay between exchange coupling between soft and hard layers and anisotropy that allows significant reduction of the switching field distribution in exchange spring media. This effect reduces the switching field distribution by about 30% compared to single-phase media. A second effect is that due to the improved thermal stability of exchange spring media over single-phase media, the jitter due to thermal fluctuation is significantly smaller for exchange spring media than for single-phase media. The influence of this overall improved switching field distribution on the transition jitter in granular recording and the bit error rate in bit-patterned magnetic recording is discussed. The transition jitter in granular recording for a distribution of Khard values of 3% in the hard layer, taking into account thermal fluctuations during recording, is estimated to be a = 0.78 nm, which is similar to the best reported calculated jitter in optimized heat-assisted recording media. PMID:27245287
Suess, D.; Fuger, M.; Abert, C.; Bruckner, F.; Vogler, C.
2016-01-01
We report two effects that lead to a significant reduction of the switching field distribution in exchange spring media. The first effect relies on a subtle mechanism of the interplay between exchange coupling between soft and hard layers and anisotropy that allows significant reduction of the switching field distribution in exchange spring media. This effect reduces the switching field distribution by about 30% compared to single-phase media. A second effect is that due to the improved thermal stability of exchange spring media over single-phase media, the jitter due to thermal fluctuation is significantly smaller for exchange spring media than for single-phase media. The influence of this overall improved switching field distribution on the transition jitter in granular recording and the bit error rate in bit-patterned magnetic recording is discussed. The transition jitter in granular recording for a distribution of Khard values of 3% in the hard layer, taking into account thermal fluctuations during recording, is estimated to be a = 0.78 nm, which is similar to the best reported calculated jitter in optimized heat-assisted recording media. PMID:27245287
NASA Astrophysics Data System (ADS)
Li, Zexian; Latva-aho, Matti
2004-12-01
Multicarrier code division multiple access (MC-CDMA) is a promising technique that combines orthogonal frequency division multiplexing (OFDM) with CDMA. In this paper, based on an alternative expression for the[InlineEquation not available: see fulltext.]-function, characteristic function and Gaussian approximation, we present a new practical technique for determining the bit error rate (BER) of multiuser MC-CDMA systems in frequency-selective Nakagami-[InlineEquation not available: see fulltext.] fading channels. The results are applicable to systems employing coherent demodulation with maximal ratio combining (MRC) or equal gain combining (EGC). The analysis assumes that different subcarriers experience independent fading channels, which are not necessarily identically distributed. The final average BER is expressed in the form of a single finite range integral and an integrand composed of tabulated functions which can be easily computed numerically. The accuracy of the proposed approach is demonstrated with computer simulations.
NASA Astrophysics Data System (ADS)
Lin, Maria Yu; Teo, Kim Keng; Chan, Kheong Sann
2015-05-01
Shingled Magnetic Recording (SMR) is an upcoming technology to see the hard disk drive industry over until heat assisted magnetic recording or another technology matures. In this work, we study the impact of variations in media parameters on the raw channel bit error rate (BER) through micromagnetic simulations and the grain flipping probability channel model in the SMR situation. This study aims to provide feedback to media designers on how media property variations influence the SMR channel performance. In particular, we analyse the effect of variations in the anisotropy constant (Ku), saturation magnetization (Ms), easy axis (ez), grain size (gs), and exchange coupling (Ax), on the written micromagnetic output and the ensuing hysteresis loop. We also compare these analyses with the channel performance on signal to noise ratio (SNR) and the raw channel BER.
Bit-error-rate performance of non-line-of-sight UV transmission with spatial diversity reception.
Xiao, Houfei; Zuo, Yong; Wu, Jian; Li, Yan; Lin, Jintong
2012-10-01
In non-line-of-sight (NLOS) UV communication links using intensity modulation with direct detection, atmospheric turbulence-induced intensity fluctuations can significantly impair link performance. To mitigate turbulence-induced fading and, therefore, to improve the bit error rate (BER) performance, spatial diversity reception can be used over NLOS UV links, which involves the deployment of multiple receivers. The maximum-likelihood (ML) spatial diversity scheme is derived for spatially correlated NLOS UV links, and the influence of various fading correlation at different receivers on the BER performance is investigated. For the dual-receiver case, ML diversity detection is compared with equal gain combining and optimal combining schemes under different turbulence intensity conditions. PMID:23027306
NASA Technical Reports Server (NTRS)
Cox, Christina B.; Coney, Thom A.
1999-01-01
The Advanced Communications Technology Satellite (ACTS) communications system operates at Ka band. ACTS uses an adaptive rain fade compensation protocol to reduce the impact of signal attenuation resulting from propagation effects. The purpose of this paper is to present the results of an analysis characterizing the improvement in VSAT performance provided by this protocol. The metric for performance is VSAT bit error rate (BER) availability. The acceptable availability defined by communication system design specifications is 99.5% for a BER of 5E-7 or better. VSAT BER availabilities with and without rain fade compensation are presented. A comparison shows the improvement in BER availability realized with rain fade compensation. Results are presented for an eight-month period and for 24 months spread over a three-year period. The two time periods represent two different configurations of the fade compensation protocol. Index Terms-Adaptive coding, attenuation, propagation, rain, satellite communication, satellites.
NASA Astrophysics Data System (ADS)
Schmidt-Nielsen, Astrid; Kallman, Howard J.
1987-11-01
The comprehension of narrowband digital speech with bit errors was tested by using a sentence verification task. The use of predicates that were either strongly or weakly related to the subjects (e.g., A toad has warts./ A toad has eyes.) varied the difficulty of the verification task. The test conditions included unprocessed and processed speech using a 2.4 kb/s (kilobits per second) linear predictive coding (LPC) voice processing algorithm with random bit error rates of 0 percent, 2 percent, and 5 percent. In general, response accuracy decreased and reaction time increased with LPC processing and with increasing bit error rates. Weakly related true sentences and strongly related false sentences were more difficult than their counterparts. Interactions between sentence type and speech processing conditions are discussed.
NASA Technical Reports Server (NTRS)
Kerczewski, Robert J.; Daugherty, Elaine S.; Kramarchuk, Ihor
1987-01-01
The performance of microwave systems and components for digital data transmission can be characterized by a plot of the bit-error rate as a function of the signal to noise ratio (or E sub b/E sub o). Methods for the efficient automated measurement of bit-error rates and signal-to-noise ratios, developed at NASA Lewis Research Center, are described. Noise measurement considerations and time requirements for measurement accuracy, as well as computer control and data processing methods, are discussed.
ERIC Educational Resources Information Center
Abedi, Razie; Latifi, Mehdi; Moinzadeh, Ahmad
2010-01-01
This study tries to answer some ever-existent questions in writing fields regarding approaching the most effective ways to give feedback to students' errors in writing by comparing the effect of error correction and error detection on the improvement of students' writing ability. In order to achieve this goal, 60 pre-intermediate English learners…
NASA Astrophysics Data System (ADS)
Hwang, Won-Young; Su, Hong-Yi; Bae, Joonwoo
2016-07-01
We study N-dimensional measurement-device-independent quantum-key-distribution protocol where one checking state is used. Only assuming that the checking state is a superposition of other N sources, we show that the protocol is secure in zero quantum-bit-error-rate case, suggesting possibility of the protocol. The method may be applied in other quantum information processing.
Bit error rate performance of pi/4-DQPSK in a frequency-selective fast Rayleigh fading channel
NASA Technical Reports Server (NTRS)
Liu, Chia-Liang; Feher, Kamilo
1991-01-01
The bit error rate (BER) performance of pi/4-differential quadrature phase shift keying (DQPSK) modems in cellular mobile communication systems is derived and analyzed. The system is modeled as a frequency-selective fast Rayleigh fading channel corrupted by additive white Gaussian noise (AWGN) and co-channel interference (CCI). The probability density function of the phase difference between two consecutive symbols of M-ary differential phase shift keying (DPSK) signals is first derived. In M-ary DPSK systems, the information is completely contained in this phase difference. For pi/4-DQPSK, the BER is derived in a closed form and calculated directly. Numerical results show that for the 24 kBd (48 kb/s) pi/4-DQPSK operated at a carrier frequency of 850 MHz and C/I less than 20 dB, the BER will be dominated by CCI if the vehicular speed is below 100 mi/h. In this derivation, frequency-selective fading is modeled by two independent Rayleigh signal paths. Only one co-channel is assumed in this derivation. The results obtained are also shown to be valid for discriminator detection of M-ary DPSK signals.
Das, Bhargab; Joseph, Joby; Singh, Kehar
2007-08-01
One of the methods for smoothing the high intensity dc peak in the Fourier spectrum for reducing the reconstruction error in a Fourier transform volume holographic data storage system is to record holograms some distance away from or in front of the Fourier plane. We present the results of our investigation on the performance of such a defocused holographic data storage system in terms of bit-error rate and content search capability. We have evaluated the relevant recording geometry through numerical simulation, by obtaining the intensity distribution at the output detector plane. This has been done by studying the bit-error rate and the content search capability as a function of the aperture size and position of the recording material away from the Fourier plane. PMID:17676163
32-Bit-Wide Memory Tolerates Failures
NASA Technical Reports Server (NTRS)
Buskirk, Glenn A.
1990-01-01
Electronic memory system of 32-bit words corrects bit errors caused by some common type of failures - even failure of entire 4-bit-wide random-access-memory (RAM) chip. Detects failure of two such chips, so user warned that ouput of memory may contain errors. Includes eight 4-bit-wide DRAM's configured so each bit of each DRAM assigned to different one of four parallel 8-bit words. Each DRAM contributes only 1 bit to each 8-bit word.
Hwang, Won-Young; Su, Hong-Yi; Bae, Joonwoo
2016-01-01
We study N-dimensional measurement-device-independent quantum-key-distribution protocol where one checking state is used. Only assuming that the checking state is a superposition of other N sources, we show that the protocol is secure in zero quantum-bit-error-rate case, suggesting possibility of the protocol. The method may be applied in other quantum information processing. PMID:27452275
Hwang, Won-Young; Su, Hong-Yi; Bae, Joonwoo
2016-01-01
We study N-dimensional measurement-device-independent quantum-key-distribution protocol where one checking state is used. Only assuming that the checking state is a superposition of other N sources, we show that the protocol is secure in zero quantum-bit-error-rate case, suggesting possibility of the protocol. The method may be applied in other quantum information processing. PMID:27452275
ERIC Educational Resources Information Center
Prewett, Peter N.; McCaffery, Lucy K.
1993-01-01
Examined relationship between Kaufman Brief Intelligence Test (K-BIT), Stanford-Binet, two-subtests short form, and Kaufman Test of Educational Achievement (K-TEA) with population of 75 academically referred students. K-BIT correlated significantly with Stanford-Binet and K-TEA Math, Reading, and Spelling scores. Results support use of K-BIT as…
NASA Astrophysics Data System (ADS)
Wang, Ran-ran; Wang, Ping; Cao, Tian; Guo, Li-xin; Yang, Yintang
2015-07-01
Based on the space diversity reception, the binary phase-shift keying (BPSK) modulated free space optical (FSO) system over Málaga (M) fading channels is investigated in detail. Under independently and identically distributed and independently and non-identically distributed dual branches, the analytical average bit error rate (ABER) expressions in terms of H-Fox function for maximal ratio combining (MRC) and equal gain combining (EGC) diversity techniques are derived, respectively, by transforming the modified Bessel function of the second kind into the integral form of Meijer G-function. Monte Carlo (MC) simulation is also provided to verify the accuracy of the presented models.
Insight into error hiding: exploration of nursing students' achievement goal orientations.
Dunn, Karee E
2014-02-01
An estimated 50% of medication errors go unreported, and error hiding is costly to hospitals and patients. This study explored one issue that may facilitate error hiding. Descriptive statistics were used to examine nursing students' achievement goal orientations in a high-fidelity simulation course. Results indicated that although this sample of nursing students held high mastery goal orientations, they also held moderate levels of performance-approach and performance-avoidance goal orientations. These goal orientations indicate that this sample is at high risk for error hiding, which places the benefits that are typically gleaned from a strong mastery orientation at risk. Understanding variables, such as goal orientation, that can be addressed in nursing education to reduce error hiding is an area of research that needs to be further explored. This article discusses the study results and evidence-based instructional practices for this sample's achievement goal orientation profile. PMID:24444007
NASA Technical Reports Server (NTRS)
Safren, H. G.
1987-01-01
The effect of atmospheric turbulence on the bit error rate of a space-to-ground near infrared laser communications link is investigated, for a link using binary pulse position modulation and an avalanche photodiode detector. Formulas are presented for the mean and variance of the bit error rate as a function of signal strength. Because these formulas require numerical integration, they are of limited practical use. Approximate formulas are derived which are easy to compute and sufficiently accurate for system feasibility studies, as shown by numerical comparison with the exact formulas. A very simple formula is derived for the bit error rate as a function of signal strength, which requires only the evaluation of an error function. It is shown by numerical calculations that, for realistic values of the system parameters, the increase in the bit error rate due to turbulence does not exceed about thirty percent for signal strengths of four hundred photons per bit or less. The increase in signal strength required to maintain an error rate of one in 10 million is about one or two tenths of a db.
NASA Astrophysics Data System (ADS)
Murshid, Syed H.; Chakravarty, Abhijit
2011-06-01
Spatial domain multiplexing (SDM) utilizes co-propagation of exactly the same wavelength in optical fibers to increase the bandwidth by integer multiples. Input signals from multiple independent single mode pigtail laser sources are launched at different input angles into a single multimode carrier fiber. The SDM channels follow helical paths and traverse through the carrier fiber without interfering with each other. The optical energy from the different sources is spatially distributed and takes the form of concentric circular donut shaped rings, where each ring corresponds to an independent laser source. At the output end of the fiber these donut shaped independent channels can be separated either with the help of bulk optics or integrated concentric optical detectors. This presents the experimental setup and results for a four channel SDM system. The attenuation and bit error rate for individual channels of such a system is also presented.
ERIC Educational Resources Information Center
Arce-Ferrer, Alvaro; Frisbie, David A.; Kolen, Michael J.
2002-01-01
Studies of the achievement test results for about 490 school districts at grade 4 and about 420 districts at grade 5 show that the error variance of estimates of change at the school level is large enough to interfere with interpretations of annual change estimates. (SLD)
Bit error rate optimization of an acousto-optic tracking system for free-space laser communications
NASA Astrophysics Data System (ADS)
Sofka, J.; Nikulin, V.
2006-02-01
Optical communications systems have been gaining momentum with the increasing demand for transmission bandwidth in the last several years. Optical cable based solutions have become an attractive alternative to copper based system in the most bandwidth demanding applications due to increased bandwidth and longer inter-repeater distances. The promise of similar benefits over radio communications systems is driving the research into free space laser communications. Along with increased communications bandwidth, a free space laser communications system offers lower power consumption and the possibility for covert data links due to the concentration of the energy of the laser into a narrow beam. A narrow beam, however, results in a requirement for much more accurate and agile steering, so that a data link can be maintained in a scenario of communication platforms in relative motion or in the presence of vibrations. This paper presents a laser beam tracking system employing an acousto-optic cell capable of deflecting a laser beam at a very high rate (order of tens of kHz). The tracking system is subjected to vibrations to simulate a realistic implementation, resulting in the increase of BER. The performance of the system can be significantly improved through digital control. A constant gain controller is complemented by a Kalman filter the parameters of which are optimized to achieve the lowest possible BER for a given vibrations spectrum.
Yousefi, Masoud; Golmohammady, Shole; Mashal, Ahmad; Kashani, Fatemeh Dabbagh
2015-11-01
In this paper, on the basis of the extended Huygens-Fresnel principle, a semianalytical expression for describing on-axis scintillation index of a partially coherent flat-topped (PCFT) laser beam of weak to moderate oceanic turbulence is derived; consequently, by using the log-normal intensity probability density function, the bit error rate (BER) is evaluated. The effects of source factors (such as wavelength, order of flatness, and beam width) and turbulent ocean parameters (such as Kolmogorov microscale, relative strengths of temperature and salinity fluctuations, rate of dissipation of the mean squared temperature, and rate of dissipation of the turbulent kinetic energy per unit mass of fluid) on propagation behavior of scintillation index, and, hence, on BER, are studied in detail. Results indicate that, in comparison with a Gaussian beam, a PCFT laser beam with a higher order of flatness is found to have lower scintillations. In addition, the scintillation index and BER are most affected when salinity fluctuations in the ocean dominate temperature fluctuations. PMID:26560913
NASA Astrophysics Data System (ADS)
Lin, Gong-Ru; Liao, Yu-Sheng
2004-04-01
The sensitivity of SONET p-i-n photodiode receivers with transimpedance amplifier (PIN-TIA) from OC-3 to OC-48 data rates measured by using a standard bit-error-rate tester (BERT) and a novel synchronous-modulation inter-mixing (SMIM) technique are compared. A threshold inter-mixed voltage of below 15.8 mV obtained by SMIM method corresponding to the sensitivity of PIN-TIA receiver beyond -32 dBm determined by BERT for the SONET OC-48 PIN-TIA receivers with a required BER of better than 10-10 is reported. the analysis interprets that the inter-mixed voltage for improving the PIN-TIA receiver sensitivity from -31 dBm to -33 dBm has to be increased from 12.5 mV to 20.4 mV. As compared to the BERT, the SMIM is a relatively simplified and low-cost technique for on-line mass-production diagnostics for measureing the sensitivity and evaluationg the BER performances of PIN-TIA receivers.
NASA Astrophysics Data System (ADS)
Kameda, Yoshio; Hashimoto, Yoshihito; Yorozu, Shinichi
We developed a 4×4 SFQ network switch prototype system and demonstrated its operation at 10Gbps. The system's core is composed of two SFQ chips: a 4×4 switch and a 6-channel voltage driver. The 4×4 switch chip contained both a switch fabric (i. e. a data path) and a switch scheduler (i. e. a controller). Both chips were attached to a multichip-module (MCM) carrier, which was then installed in a cryocooled system with 32 10-Gbps ports. Each chip contained about 2100 Josephson junctions on a 5-mm×5-mm die. An NEC standard 2.5-kA/cm2 fabrication process was used for the switch chip. We increased the critical current density to 10kA/cm2 for the driver chip to improve speed while maintaining wide bias margins. MCM implementation enabled us to use a hybrid critical current density technology. Voltage pulses were transferred between two chips through passive transmission lines on the MCM carrier. The cryocooled system was cooled down to about 4K using a two-stage 1-W cryocooler. We correctly operated the whole system at 10Gbps. The switch scheduler, which is driven by an on-chip clock generator, operated at 40GHz. The speed gap between SFQ and room temperature devices was filled by on-chip SFQ FIFO buffers or shift registers. We measured the bit error rate at 10Gbps and found that it was on the order of 10-13 for the 4×4 SFQ switch fabric. In addition, using semiconductor interface circuitry, we built a four-port SFQ Ethernet switch. All the components except for a compressor were installed in a standard 19-inch rack, filling a space 21 U (933.5mm or 36.75 inches) in height. After four personal computers (PCs) were connected to the switch, we have successfully transferred video data between them.
Liu, Yun; Zhao, Shanghong; Gong, Zizheng; Zhao, Jing; Dong, Chen; Li, Xuan
2016-04-10
Displacement damage (DD) effect induced bit error ratio (BER) performance degradations in on-off keying (OOK), pulse position modulation (PPM), differential phase-shift keying (DPSK), and homodyne binary phase shift keying (BPSK) based systems were simulated and discussed under 1 MeV neutron irradiation to a total fluence of 1×10^{12} n/cm^{2} in this paper. Degradation of main optoelectronic devices included in communication systems were analyzed on the basis of existing experimental data. The system BER degradation was subsequently simulated and the variations of BER with different neutron irradiation location were also achieved. The result shows that DD on an Er-doped fiber amplifier (EDFA) is the dominant cause of system degradation, and a BPSK-based system performs better than the other three systems against DD. In order to improve radiation hardness of communication systems against DD, protection and enhancement of EDFA are required, and the use of a homodyne BPSK modulation scheme is a considered choice. PMID:27139876
Inter-bit prediction based on maximum likelihood estimate for distributed video coding
NASA Astrophysics Data System (ADS)
Klepko, Robert; Wang, Demin; Huchet, Grégory
2010-01-01
Distributed Video Coding (DVC) is an emerging video coding paradigm for the systems that require low complexity encoders supported by high complexity decoders. A typical real world application for a DVC system is mobile phones with video capture hardware that have a limited encoding capability supported by base-stations with a high decoding capability. Generally speaking, a DVC system operates by dividing a source image sequence into two streams, key frames and Wyner-Ziv (W) frames, with the key frames being used to represent the source plus an approximation to the W frames called S frames (where S stands for side information), while the W frames are used to correct the bit errors in the S frames. This paper presents an effective algorithm to reduce the bit errors in the side information of a DVC system. The algorithm is based on the maximum likelihood estimation to help predict future bits to be decoded. The reduction in bit errors in turn reduces the number of parity bits needed for error correction. Thus, a higher coding efficiency is achieved since fewer parity bits need to be transmitted from the encoder to the decoder. The algorithm is called inter-bit prediction because it predicts the bit-plane to be decoded from previously decoded bit-planes, one bitplane at a time, starting from the most significant bit-plane. Results provided from experiments using real-world image sequences show that the inter-bit prediction algorithm does indeed reduce the bit rate by up to 13% for our test sequences. This bit rate reduction corresponds to a PSNR gain of about 1.6 dB for the W frames.
Low bit rate speech transmission
NASA Astrophysics Data System (ADS)
Rothweiler, J.; Bertrand, J.
The achievement of very low bit rates in all-digital military communications is important in tactical systems. Attention is presently given to a 400-2400 bit/sec system in which feature extraction is performed by standard linear predictive coding together with pattern matching by vector quantization and trellis coding. Some part of this system have been implemented in hardware, and others in simulation. Diagnostic rhyme test results are presented to indicate the performance of the system at various bit rates.
Least Reliable Bits Coding (LRBC) for high data rate satellite communications
NASA Astrophysics Data System (ADS)
Vanderaar, Mark; Wagner, Paul; Budinger, James
1992-02-01
An analysis and discussion of a bandwidth efficient multi-level/multi-stage block coded modulation technique called Least Reliable Bits Coding (LRBC) is presented. LRBC uses simple multi-level component codes that provide increased error protection on increasingly unreliable modulated bits in order to maintain an overall high code rate that increases spectral efficiency. Further, soft-decision multi-stage decoding is used to make decisions on unprotected bits through corrections made on more protected bits. Using analytical expressions and tight performance bounds it is shown that LRBC can achieve increased spectral efficiency and maintain equivalent or better power efficiency compared to that of Binary Phase Shift Keying (BPSK). Bit error rates (BER) vs. channel bit energy with Additive White Gaussian Noise (AWGN) are given for a set of LRB Reed-Solomon (RS) encoded 8PSK modulation formats with an ensemble rate of 8/9. All formats exhibit a spectral efficiency of 2.67 = (log2(8))(8/9) information bps/Hz. Bit by bit coded and uncoded error probabilities with soft-decision information are determined. These are traded with with code rate to determine parameters that achieve good performance. The relative simplicity of Galois field algebra vs. the Viterbi algorithm and the availability of high speed commercial Very Large Scale Integration (VLSI) for block codes indicates that LRBC using block codes is a desirable method for high data rate implementations.
Least Reliable Bits Coding (LRBC) for high data rate satellite communications
NASA Technical Reports Server (NTRS)
Vanderaar, Mark; Wagner, Paul; Budinger, James
1992-01-01
An analysis and discussion of a bandwidth efficient multi-level/multi-stage block coded modulation technique called Least Reliable Bits Coding (LRBC) is presented. LRBC uses simple multi-level component codes that provide increased error protection on increasingly unreliable modulated bits in order to maintain an overall high code rate that increases spectral efficiency. Further, soft-decision multi-stage decoding is used to make decisions on unprotected bits through corrections made on more protected bits. Using analytical expressions and tight performance bounds it is shown that LRBC can achieve increased spectral efficiency and maintain equivalent or better power efficiency compared to that of Binary Phase Shift Keying (BPSK). Bit error rates (BER) vs. channel bit energy with Additive White Gaussian Noise (AWGN) are given for a set of LRB Reed-Solomon (RS) encoded 8PSK modulation formats with an ensemble rate of 8/9. All formats exhibit a spectral efficiency of 2.67 = (log2(8))(8/9) information bps/Hz. Bit by bit coded and uncoded error probabilities with soft-decision information are determined. These are traded with with code rate to determine parameters that achieve good performance. The relative simplicity of Galois field algebra vs. the Viterbi algorithm and the availability of high speed commercial Very Large Scale Integration (VLSI) for block codes indicates that LRBC using block codes is a desirable method for high data rate implementations.
Achieving minimum-error discrimination of an arbitrary set of laser-light pulses
NASA Astrophysics Data System (ADS)
da Silva, Marcus P.; Guha, Saikat; Dutton, Zachary
2013-05-01
Laser light is widely used for communication and sensing applications, so the optimal discrimination of coherent states—the quantum states of light emitted by an ideal laser—has immense practical importance. Due to fundamental limits imposed by quantum mechanics, such discrimination has a finite minimum probability of error. While concrete optical circuits for the optimal discrimination between two coherent states are well known, the generalization to larger sets of coherent states has been challenging. In this paper, we show how to achieve optimal discrimination of any set of coherent states using a resource-efficient quantum computer. Our construction leverages a recent result on discriminating multicopy quantum hypotheses [Blume-Kohout, Croke, and Zwolak, arXiv:1201.6625]. As illustrative examples, we analyze the performance of discriminating a ternary alphabet and show how the quantum circuit of a receiver designed to discriminate a binary alphabet can be reused in discriminating multimode hypotheses. Finally, we show that our result can be used to achieve the quantum limit on the rate of classical information transmission on a lossy optical channel, which is known to exceed the Shannon rate of all conventional optical receivers.
A 25μm pitch LWIR staring focal plane array with pixel-level 15-bit ADC ROIC achieving 2mK NETD
NASA Astrophysics Data System (ADS)
Bisotto, Sylvette; de Borniol, Eric; Mollard, Laurent; Guellec, Fabrice; Peizerat, Arnaud; Tchagaspanian, Micha"l.; Castelein, Pierre; Maillart, Patrick
2010-10-01
CEA-Leti MINATEC has been involved in infrared focal plane array (IRFPA) development since many years, with performing HgCdTe in-house process from SWIR to LWIR and more recently in focusing its work on new ROIC architectures. The trend is to integrate advanced functions into the CMOS design for the purpose of applications demanding a breakthrough in Noise Equivalent Temperature Difference (NETD) performances (reaching the mK in LWIR band) or a high dynamic range (HDR) with high-gain APDs. In this paper, we present a mid-TV format focal plane array (FPA) operating in LWIR with 25μm pixel pitch, including a new readout IC (ROIC) architecture based on pixel-level charge packets counting. The ROIC has been designed in a standard 0.18μm 6-metal CMOS process, LWIR n/p HgCdTe detectors were fabricated with CEA-Leti in-house process. The FPA operates at 50Hz frame rate in a snapshot integrate-while-read (IWR) mode, allowing a large integration time. While classical pixel architectures are limited by the charge well capacity, this architecture exhibits a large well capacity (near 3Ge-) and the 15-bit pixel level ADC preserves an excellent signal-to-noise ratio (SNR) at full well. These characteristics are essential for LWIR FPAs as broad intra-scene dynamic range imaging requires high sensitivity. The main design challenges for this digital pixel array (SNR, power consumption and layout density) are discussed. The electro-optical results demonstrating a peak NETD value of 2mK and images taken with the FPA are presented. They validate both the pixel-level ADC concept and its circuit implementation. A previously unreleased SNR of 90dB is achieved.
ERIC Educational Resources Information Center
Keuning, Jos; Hemker, Bas
2014-01-01
The data collection of a cohort study requires making many decisions. Each decision may introduce error in the statistical analyses conducted later on. In the present study, a procedure was developed for estimation of the error made due to the composition of the sample, the item selection procedure, and the test equating process. The math results…
NASA Astrophysics Data System (ADS)
Gurkin, N. V.; Konyshev, V. A.; Nanii, O. E.; Novikov, A. G.; Treshchikov, V. N.; Ubaydullaev, R. R.
2015-01-01
We have studied experimentally and using numerical simulations and a phenomenological analytical model the dependences of the bit error rate (BER) on the signal power and length of a coherent single-span communication line with transponders employing polarisation division multiplexing and four-level phase modulation (100 Gbit s-1 DP-QPSK format). In comparing the data of the experiment, numerical simulations and theoretical analysis, we have found two optimal powers: the power at which the BER is minimal and the power at which the fade margin in the line is maximal. We have derived and analysed the dependences of the BER on the optical signal power at the fibre line input and the dependence of the admissible input signal power range for implementation of the communication lines with a length from 30 - 50 km up to a maximum length of 250 km.
Gurkin, N V; Konyshev, V A; Novikov, A G; Treshchikov, V N; Ubaydullaev, R R
2015-01-31
We have studied experimentally and using numerical simulations and a phenomenological analytical model the dependences of the bit error rate (BER) on the signal power and length of a coherent single-span communication line with transponders employing polarisation division multiplexing and four-level phase modulation (100 Gbit s{sup -1} DP-QPSK format). In comparing the data of the experiment, numerical simulations and theoretical analysis, we have found two optimal powers: the power at which the BER is minimal and the power at which the fade margin in the line is maximal. We have derived and analysed the dependences of the BER on the optical signal power at the fibre line input and the dependence of the admissible input signal power range for implementation of the communication lines with a length from 30 – 50 km up to a maximum length of 250 km. (optical transmission of information)
Efficient Bit-to-Symbol Likelihood Mappings
NASA Technical Reports Server (NTRS)
Moision, Bruce E.; Nakashima, Michael A.
2010-01-01
This innovation is an efficient algorithm designed to perform bit-to-symbol and symbol-to-bit likelihood mappings that represent a significant portion of the complexity of an error-correction code decoder for high-order constellations. Recent implementation of the algorithm in hardware has yielded an 8- percent reduction in overall area relative to the prior design.
NASA Technical Reports Server (NTRS)
Costello, Daniel J., Jr.; Courturier, Servanne; Levy, Yannick; Mills, Diane G.; Perez, Lance C.; Wang, Fu-Quan
1993-01-01
In his seminal 1948 paper 'The Mathematical Theory of Communication,' Claude E. Shannon derived the 'channel coding theorem' which has an explicit upper bound, called the channel capacity, on the rate at which 'information' could be transmitted reliably on a given communication channel. Shannon's result was an existence theorem and did not give specific codes to achieve the bound. Some skeptics have claimed that the dramatic performance improvements predicted by Shannon are not achievable in practice. The advances made in the area of coded modulation in the past decade have made communications engineers optimistic about the possibility of achieving or at least coming close to channel capacity. Here we consider the possibility in the light of current research results.
Performance of concatenated codes using 8-bit and 10-bit Reed-Solomon codes
NASA Technical Reports Server (NTRS)
Pollara, F.; Cheung, K.-M.
1989-01-01
The performance improvement of concatenated coding systems using 10-bit instead of 8-bit Reed-Solomon codes is measured by simulation. Three inner convolutional codes are considered: (7,1/2), (15,1/4), and (15,1/6). It is shown that approximately 0.2 dB can be gained at a bit error rate of 10(-6). The loss due to nonideal interleaving is also evaluated. Performance comparisons at very low bit error rates may be relevant for systems using data compression.
Positional information, in bits
Dubuis, Julien O.; Tkačik, Gašper; Wieschaus, Eric F.; Gregor, Thomas; Bialek, William
2013-01-01
Cells in a developing embryo have no direct way of “measuring” their physical position. Through a variety of processes, however, the expression levels of multiple genes come to be correlated with position, and these expression levels thus form a code for “positional information.” We show how to measure this information, in bits, using the gap genes in the Drosophila embryo as an example. Individual genes carry nearly two bits of information, twice as much as would be expected if the expression patterns consisted only of on/off domains separated by sharp boundaries. Taken together, four gap genes carry enough information to define a cell’s location with an error bar of along the anterior/posterior axis of the embryo. This precision is nearly enough for each cell to have a unique identity, which is the maximum information the system can use, and is nearly constant along the length of the embryo. We argue that this constancy is a signature of optimality in the transmission of information from primary morphogen inputs to the output of the gap gene network. PMID:24089448
Hood, Michael
1986-01-01
A mounting movable with respect to an adjacent hard face has a projecting drag bit adapted to engage the hard face. The drag bit is disposed for movement relative to the mounting by encounter of the drag bit with the hard face. That relative movement regulates a valve in a water passageway, preferably extending through the drag bit, to play a stream of water in the area of contact of the drag bit and the hard face and to prevent such water play when the drag bit is out of contact with the hard face.
Hood, M.
1986-02-11
A mounting movable with respect to an adjacent hard face has a projecting drag bit adapted to engage the hard face. The drag bit is disposed for movement relative to the mounting by encounter of the drag bit with the hard face. That relative movement regulates a valve in a water passageway, preferably extending through the drag bit, to play a stream of water in the area of contact of the drag bit and the hard face and to prevent such water play when the drag bit is out of contact with the hard face. 4 figs.
One-bit digital-to-analog converter based on rapid single flux quantum circuit
NASA Astrophysics Data System (ADS)
Hirayama, F.; Maezawa, M.; Suzuki, M.
2007-10-01
Rapid single flux quantum digital-to-analog (D/A) converters which synthesize arbitrary waveforms with metrological accuracy are under development. We propose a 1-bit RSFQ D/A converter which is expected to operate at higher sampling frequencies than the multi-bit converter and is suitable for multi-chip operation to achieve the output voltages exceeding 100 mV. Calculations of the noise power and the attenuation of the signal suggested that the rms error in a 10 kHz sine wave synthesized by the 1-bit converter with a third-order low-pass filter can be smaller than 10-7 at the sampling frequency of 100 MHz. A prototype 1-bit D/A converter was fabricated and the generation of dc voltages was confirmed as expected.
NASA Astrophysics Data System (ADS)
Koike, Hiroki; Ohsawa, Takashi; Miura, Sadahiko; Honjo, Hiroaki; Ikeda, Shoji; Hanyu, Takahiro; Ohno, Hideo; Endoh, Tetsuo
2015-04-01
A spintronic-based power-gated micro-processing unit (MPU) is proposed. It includes a power control circuit activated by the newly supported power-off instruction for the deep-sleep mode. These means enable the power-off procedure for the MPU to be executed appropriately. A test chip was designed and fabricated using 90 nm CMOS and an additional 100 nm MTJ process; it was successfully operated. The guideline of the energy reduction effects for this MPU was presented, using the estimation based on the measurement results of the test chip. The result shows that a large operation energy reduction of 1/28 can be achieved when the operation duty is 10%, under the condition of a sufficient number of idle clock cycles.
Bidirectional synchronization and hierarchical error correction for robust image transmission
NASA Astrophysics Data System (ADS)
Li, HongZhi; Chen, Chang W.
1998-12-01
In this paper, we present a novel joint source and channel image coding scheme for noisy channel transmission. The proposed scheme consists of two innovative components: (1) Intelligent bi-directional synchronization, and (2) Layered bit-plane error protection. The bi-directional synchronization is able to recover the coding synchronization when any single or even when two consecutive synchronization codes are corrupted by the channel noise. With synchronized partition, unequal error protection for each bit-plane can be designed to suit for a wide range of channel environments. The hierarchical error protection strategy is based on the analysis of bit-plane error sensitivity, aiming at achieving an optimal joint source and channel coding when the compressed image data are transmitted over noisy channels. Experimental results over extensive channel simulations show that the proposed scheme outperforms the approach proposed by Sherwood and Zeger who have reported the best numerical results in the literature.
Deterministic relativistic quantum bit commitment
NASA Astrophysics Data System (ADS)
Adlam, Emily; Kent, Adrian
2015-06-01
We describe new unconditionally secure bit commitment schemes whose security is based on Minkowski causality and the monogamy of quantum entanglement. We first describe an ideal scheme that is purely deterministic, in the sense that neither party needs to generate any secret randomness at any stage. We also describe a variant that allows the committer to proceed deterministically, requires only local randomness generation from the receiver, and allows the commitment to be verified in the neighborhood of the unveiling point. We show that these schemes still offer near-perfect security in the presence of losses and errors, which can be made perfect if the committer uses an extra single random secret bit. We discuss scenarios where these advantages are significant.
Dokos, James A.
1997-01-01
A drill bit loader for loading a tapered shank of a drill bit into a similarly tapered recess in the end of a drill spindle. The spindle has a transverse slot at the inner end of the recess. The end of the tapered shank of the drill bit has a transverse tang adapted to engage in the slot so that the drill bit will be rotated by the spindle. The loader is in the form of a cylinder adapted to receive the drill bit with the shank projecting out of the outer end of the cylinder. Retainer pins prevent rotation of the drill bit in the cylinder. The spindle is lowered to extend the shank of the drill bit into the recess in the spindle and the spindle is rotated to align the slot in the spindle with the tang on the shank. A spring unit in the cylinder is compressed by the drill bit during its entry into the recess of the spindle and resiliently drives the tang into the slot in the spindle when the tang and slot are aligned.
Dokos, J.A.
1997-12-30
A drill bit loader is described for loading a tapered shank of a drill bit into a similarly tapered recess in the end of a drill spindle. The spindle has a transverse slot at the inner end of the recess. The end of the tapered shank of the drill bit has a transverse tang adapted to engage in the slot so that the drill bit will be rotated by the spindle. The loader is in the form of a cylinder adapted to receive the drill bit with the shank projecting out of the outer end of the cylinder. Retainer pins prevent rotation of the drill bit in the cylinder. The spindle is lowered to extend the shank of the drill bit into the recess in the spindle and the spindle is rotated to align the slot in the spindle with the tang on the shank. A spring unit in the cylinder is compressed by the drill bit during its entry into the recess of the spindle and resiliently drives the tang into the slot in the spindle when the tang and slot are aligned. 5 figs.
Multi-Bit Quantum Private Query
NASA Astrophysics Data System (ADS)
Shi, Wei-Xu; Liu, Xing-Tong; Wang, Jian; Tang, Chao-Jing
2015-09-01
Most of the existing Quantum Private Queries (QPQ) protocols provide only single-bit queries service, thus have to be repeated several times when more bits are retrieved. Wei et al.'s scheme for block queries requires a high-dimension quantum key distribution system to sustain, which is still restricted in the laboratory. Here, based on Markus Jakobi et al.'s single-bit QPQ protocol, we propose a multi-bit quantum private query protocol, in which the user can get access to several bits within one single query. We also extend the proposed protocol to block queries, using a binary matrix to guard database security. Analysis in this paper shows that our protocol has better communication complexity, implementability and can achieve a considerable level of security.
Yang, Aiying; Li, Xiangming; Jiang, Tao
2012-04-23
Combination of overlapping pulse position modulation and pulse width modulation at the transmitter and grouped bit-flipping algorithm for low-density parity-check decoding at the receiver are proposed for visible Light Emitting Diode (LED) indoor communication system in this paper. The results demonstrate that, with the same Photodetector, the bit rate can be increased and the performance of the communication system can be improved by the scheme we proposed. Compared with the standard bit-flipping algorithm, the grouped bit-flipping algorithm can achieve more than 2.0 dB coding gain at bit error rate of 10^{-5}. By optimizing the encoding of overlapping pulse position modulation and pulse width modulation symbol, the performance can be further improved. It is reasonably expected that the bit rate can be upgraded to 400 Mbit/s with a single available LED, thus transmission rate beyond 1 Gbit/s is foreseen by RGB LEDs. PMID:22535108
ERIC Educational Resources Information Center
Rodrigo, Ma. Mercedes T.; Andallaza, Thor Collin S.; Castro, Francisco Enrique Vicente G.; Armenta, Marc Lester V.; Dy, Thomas T.; Jadud, Matthew C.
2013-01-01
In this article we quantitatively and qualitatively analyze a sample of novice programmer compilation log data, exploring whether (or how) low-achieving, average, and high-achieving students vary in their grasp of these introductory concepts. High-achieving students self-reported having the easiest time learning the introductory programming…
Barr, J. D.
1985-12-17
A drill bit comprises a bit body having an operating end face. A plurality of self-sharpening cutters are mounted in the bit body and extend through the operating end face. The cutters have cutting faces adapted to engage an earth formation and cut the earth formation to a desired three-dimensional profile. The cutting faces define surfaces having back rake angles which decrease with distance from the profile. The individual cutting faces may be inwardly concave in a plane parallel to the intended direction of motion of the cutter in use.
NASA Astrophysics Data System (ADS)
Bhooplapur, Sharad; Akbulut, Mehmetkan; Quinlan, Franklyn; Delfyett, Peter J.
2010-04-01
A novel scheme for recognition of electronic bit-sequences is demonstrated. Two electronic bit-sequences that are to be compared are each mapped to a unique code from a set of Walsh-Hadamard codes. The codes are then encoded in parallel on the spectral phase of the frequency comb lines from a frequency-stabilized mode-locked semiconductor laser. Phase encoding is achieved by using two independent spatial light modulators based on liquid crystal arrays. Encoded pulses are compared using interferometric pulse detection and differential balanced photodetection. Orthogonal codes eight bits long are compared, and matched codes are successfully distinguished from mismatched codes with very low error rates, of around 10-18. This technique has potential for high-speed, high accuracy recognition of bit-sequences, with applications in keyword searches and internet protocol packet routing.
Semi-fixed-length motion vector coding for H.263-based low bit rate video compression.
Côté, G; Gallant, M; Kossentini, F
1999-01-01
We present a semi-fixed-length motion vector coding method for H.263-based low bit rate video compression. The method exploits structural constraints within the motion field. The motion vectors are encoded using semi-fixed-length codes, yielding essentially the same levels of rate-distortion performance and subjective quality achieved by H.263's Huffman-based variable length codes in a noiseless environment. However, such codes provide substantially higher error resilience in a noisy environment. PMID:18267417
Bit corruption correlation and autocorrelation in a stochastic binary nano-bit system
NASA Astrophysics Data System (ADS)
Sa-nguansin, Suchittra
2014-10-01
The corruption process of a binary nano-bit model resulting from an interaction with N stochastically-independent Brownian agents (BAs) is studied with the help of Monte-Carlo simulations and analytic continuum theory to investigate the data corruption process through the measurement of the spatial two-point correlation and the autocorrelation of bit corruption at the origin. By taking into account a more realistic correlation between bits, this work will contribute to the understanding of the soft error or the corruption of data stored in nano-scale devices.
Numerical optimization of writer and media for bit patterned magnetic recording
NASA Astrophysics Data System (ADS)
Kovacs, A.; Oezelt, H.; Schabes, M. E.; Schrefl, T.
2016-07-01
In this work, we present a micromagnetic study of the performance potential of bit-patterned (BP) magnetic recording media via joint optimization of the design of the media and of the magnetic write heads. Because the design space is large and complex, we developed a novel computational framework suitable for parallel implementation on compute clusters. Our technique combines advanced global optimization algorithms and finite-element micromagnetic solvers. Targeting data bit densities of 4 Tb/in2, we optimize designs for centered, staggered, and shingled BP writing. The magnetization dynamics of the switching of the exchange-coupled composite BP islands of the media is treated micromagnetically. Our simulation framework takes into account not only the dynamics of on-track errors but also the thermally induced adjacent-track erasure. With co-optimized write heads, the results show superior performance of shingled BP magnetic recording where we identify two particular designs achieving write bit-error rates of 1.5 ×10-8 and 8.4 ×10-8 , respectively. A detailed description of the key design features of these designs is provided and contrasted with centered and staggered BP designs which yielded write bit error rates of only 2.8 ×10-3 (centered design) and 1.7 ×10-2 (staggered design) even under optimized conditions.
Critique of a Hughes shuttle Ku-band data sampler/bit synchronizer
NASA Technical Reports Server (NTRS)
Holmes, J. K.
1980-01-01
An alternative bit synchronizer proposed for shuttle was analyzed in a noise-free environment by considering the basic operation of the loop via timing diagrams and by linearizing the bit synchronizer as an equivalent, continuous, phased-lock loop (PLL). The loop is composed of a high-frequency phase-frequency detector which is capable of detecting both phase and frequency errors and is used to track the clock, and a bit transition detector which attempts to track the transitions of the data bits. It was determined that the basic approach was a good design which, with proper implementation of the accumulator, up/down counter and logic should provide accurate mid-bit sampling with symmetric bits. However, when bit asymmetry occurs, the bit synchronizer can lock up with a large timing error, yet be quasi-stable (timing will not change unless the clock and bit sequence drift). This will result in incorrectly detecting some bits.
Heat-assisted magnetic recording of bit-patterned media beyond 10 Tb/in2
NASA Astrophysics Data System (ADS)
Vogler, Christoph; Abert, Claas; Bruckner, Florian; Suess, Dieter; Praetorius, Dirk
2016-03-01
The limits of areal storage density that is achievable with heat-assisted magnetic recording are unknown. We addressed this central question and investigated the areal density of bit-patterned media. We analyzed the detailed switching behavior of a recording bit under various external conditions, allowing us to compute the bit error rate of a write process (shingled and conventional) for various grain spacings, write head positions, and write temperatures. Hence, we were able to optimize the areal density yielding values beyond 10 Tb/in2. Our model is based on the Landau-Lifshitz-Bloch equation and uses hard magnetic recording grains with a 5-nm diameter and 10-nm height. It assumes a realistic distribution of the Curie temperature of the underlying material, grain size, as well as grain and head position.
Morrell, Roger J.; Larson, David A.; Ruzzi, Peter L.
1994-01-01
A double acting bit holder that permits bits held in it to be resharpened during cutting action to increase energy efficiency by reducing the amount of small chips produced. The holder consist of: a stationary base portion capable of being fixed to a cutter head of an excavation machine and having an integral extension therefrom with a bore hole therethrough to accommodate a pin shaft; a movable portion coextensive with the base having a pin shaft integrally extending therefrom that is insertable in the bore hole of the base member to permit the moveable portion to rotate about the axis of the pin shaft; a recess in the movable portion of the holder to accommodate a shank of a bit; and a biased spring disposed in adjoining openings in the base and moveable portions of the holder to permit the moveable portion to pivot around the pin shaft during cutting action of a bit fixed in a turret to allow front, mid and back positions of the bit during cutting to lessen creation of small chip amounts and resharpen the bit during excavation use.
Continuous operation of high bit rate quantum key distribution
NASA Astrophysics Data System (ADS)
Dixon, A. R.; Yuan, Z. L.; Dynes, J. F.; Sharpe, A. W.; Shields, A. J.
2010-04-01
We demonstrate a quantum key distribution with a secure bit rate exceeding 1 Mbit/s over 50 km fiber averaged over a continuous 36 h period. Continuous operation of high bit rates is achieved using feedback systems to control path length difference and polarization in the interferometer and the timing of the detection windows. High bit rates and continuous operation allows finite key size effects to be strongly reduced, achieving a key extraction efficiency of 96% compared to keys of infinite lengths.
Bit-serial neuroprocessor architecture
NASA Technical Reports Server (NTRS)
Tawel, Raoul (Inventor)
2001-01-01
A neuroprocessor architecture employs a combination of bit-serial and serial-parallel techniques for implementing the neurons of the neuroprocessor. The neuroprocessor architecture includes a neural module containing a pool of neurons, a global controller, a sigmoid activation ROM look-up-table, a plurality of neuron state registers, and a synaptic weight RAM. The neuroprocessor reduces the number of neurons required to perform the task by time multiplexing groups of neurons from a fixed pool of neurons to achieve the successive hidden layers of a recurrent network topology.
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Lubrication of rotary rock bits
MacPhail, J.; Gardner, H.
1996-12-01
The rotary rock bit is designed so that both the bearings and cutting structure work together as one unit. Should the bearings wear prematurely before the cutting structure is worn out, then the complete bit will rapidly deteriorate leading to a shortened bit life. The optimum bit run is when the bearings and cutting structure wear out simultaneously, having obtained a good footage and rate of penetration. This paper discusses reasons why users of rotary air blast hole bits encounter premature bit failure due to bearing failure. It also discusses a lubrication system designed for rotary rock bits to combat bearing failure.
Dissipation-induced continuous quantum error correction for superconducting circuits
NASA Astrophysics Data System (ADS)
Cohen, Joachim; Mirrahimi, Mazyar
2014-12-01
Quantum error correction (QEC) is a crucial step towards long coherence times required for efficient quantum information processing. One major challenge in this direction concerns the fast real-time analysis of error syndrome measurements and the associated feedback control. Recent proposals on autonomous QEC (AQEC) have opened new perspectives to overcome this difficulty. Here, we design an AQEC scheme based on quantum reservoir engineering adapted to superconducting qubits. We focus on a three-qubit bit-flip code, where three transmon qubits are dispersively coupled to a few low-Q resonator modes. By applying only continuous-wave drives of fixed but well-chosen frequencies and amplitudes, we engineer an effective interaction Hamiltonian to evacuate the entropy created by eventual bit-flip errors. We provide a full analytical and numerical study of the protocol while introducing the main limitations on the achievable error correction rates.
NASA Astrophysics Data System (ADS)
Daly, Scott J.; Feng, Xiaofan
2003-01-01
Continuous tone, or "contone", imagery usually has 24 bits/pixel as a minimum, with eight bits each for the three primaries in typical displays. However, lower-cost displays constrain this number because of various system limitations. Conversely, high quality displays seek to achieve 9-10 bits/pixel/color, though there may be system bottlenecks limited at 8. The two main artifacts from reduced bit-depth are contouring and loss of amplitude detail; these can be prevented by dithering the image prior to these bit-depth losses. Early work in this area includes Roberts" noise modulation technique, Mista"s blue noise mask, Tyler"s technique of bit-stealing, and Mulligan"s use of the visual system"s spatiotemporal properties for spatiotemporal dithering. However, most halftoning/dithering work was primarily directed to displays at the lower end of bits/pixel (e.g., 1 bit as in halftoning) and higher ppi. Like Tyler, we approach the problem from the higher end of bits/pixel/color, say 6-8, and use available high frequency color content to generate even higher luminance amplitude resolution. Bit-depth extension with a high starting bit-depth (and often lower spatial resolution) changes the game substantially from halftoning experience. For example, complex algorithms like error diffusion and annealing are not needed, just the simple addition of noise. Instead of a spatial dither, it is better to use an amplitude dither, termed microdither by Pappas. We have looked at methods of generating the highest invisible opponent color spatiotemporal noise and other patterns, and have used Ahumada"s concept of equivalent input noise to guide our work. This paper will report on techniques and observations made in achieving contone quality on ~100 ppi 6 bits/pixel/color LCD displays with no visible dither patterns, noise, contours, or loss of amplitude detail at viewing distances as close as the near focus limit (~120 mm). These include the interaction of display nonlinearities and
Error control coding for multi-frequency modulation
NASA Astrophysics Data System (ADS)
Ives, Robert W.
1990-06-01
Multi-frequency modulation (MFM) has been developed at NPS using both quadrature-phase-shift-keyed (QPSK) and quadrature-amplitude-modulated (QAM) signals with good bit error performance at reasonable signal-to-noise ratios. Improved performance can be achieved by the introduction of error control coding. This report documents a FORTRAN simulation of the implementation of error control coding into an MFM communication link with additive white Gaussian noise. Four Reed-Solomon codes were incorporated, two for 16-QAM and two for 32-QAM modulation schemes. The error control codes used were modified from the conventional Reed-Solomon codes in that one information symbol was sacrificed to parity in order to use a simplified decoding algorithm which requires no iteration and enhances error detection capability. Bit error rates as a function of SNR and E(sub b)/N(sub 0) were analyzed, and bit error performance was weighed against reduction in information rate to determine the value of the codes.
Ford, G.A.
1987-09-22
A continuous coring drill bit is described comprising: (a) body means defining a vertical axis and adapted for connection to drill pipe and forming an internal body cavity disposed in eccentric relation with the vertical axis and a generally circular throat in communication with the body cavity for conducting drilling fluid. The throat defining a throat axis coincident with the vertical axis and being of a configuration permitting passage of a formation core into the body cavity; (b) a generally cylindrical tubular core breaker being rotatably mounted within the body cavity and defining a vertical axis of rotation of generally parallel and offset relation with the vertical axis of the body means; and (c) a buttress element extending inwardly from the core breaker and adapted to contact the formation core. Upon each rotation of the drill bit the buttress element applying transverse force to the core for fracturing of the core into sections sufficiently small for transport by the drilling fluid.
NASA Astrophysics Data System (ADS)
Kartiwa, Iwa; Jung, Sang-Min; Hong, Moon-Ki; Han, Sang-Kook
2013-06-01
We experimentally demonstrate the use of millimeter-wave signal generation by optical carrier suppression (OCS) method using single-drive Mach-Zehnder modulator as a light sources seed for 20 Gb/s WDM-OFDM-PON in 20-km single fiber loopback transmission based on cost-effective RSOA modulation. Practical discrete rate adaptive bit loading algorithm was employed in this colorless ONU system to maximize the achievable bit rate for an average bit error rate (BER) below 2 × 10-3.
Sandford, II, Maxwell T.; Handel, Theodore G.; Ettinger, J. Mark
1999-01-01
A method of embedding auxiliary information into the digital representation of host data containing noise in the low-order bits. The method applies to digital data representing analog signals, for example digital images. The method reduces the error introduced by other methods that replace the low-order bits with auxiliary information. By a substantially reverse process, the embedded auxiliary data can be retrieved easily by an authorized user through use of a digital key. The modular error embedding method includes a process to permute the order in which the host data values are processed. The method doubles the amount of auxiliary information that can be added to host data values, in comparison with bit-replacement methods for high bit-rate coding. The invention preserves human perception of the meaning and content of the host data, permitting the addition of auxiliary data in the amount of 50% or greater of the original host data.
A novel bit-wise adaptable entropy coding technique
NASA Technical Reports Server (NTRS)
Kiely, A.; Klimesh, M.
2001-01-01
We present a novel entropy coding technique which is adaptable in that each bit to be encoded may have an associated probability esitmate which depends on previously encoded bits. The technique may have advantages over arithmetic coding. The technique can achieve arbitrarily small redundancy and admits a simple and fast decoder.
Core bit design reduces mud invasion, improves ROP
Clydesdale, G. ); Leseultre, A.; Lamine, E. )
1994-08-08
A recently developed core bit reduces fluid invasion in the cut core by minimizing the exposure to the drilling fluid and by increasing the rate of penetration (ROP). A high ROP during coring is one of the major factors in reducing mud filtrate invasion in cores. This new low-invasion polycrystalline diamond compact (PDC) core bit was designed to achieve a higher ROP than conventional PDC core bits without detriment to the cutting structure. The paper describes the bit and its operation, results of lab tests, fluid dynamics, and results of field tests.
Entanglement and Quantum Error Correction with Superconducting Qubits
NASA Astrophysics Data System (ADS)
Reed, Matthew
2015-03-01
Quantum information science seeks to take advantage of the properties of quantum mechanics to manipulate information in ways that are not otherwise possible. Quantum computation, for example, promises to solve certain problems in days that would take a conventional supercomputer the age of the universe to decipher. This power does not come without a cost however, as quantum bits are inherently more susceptible to errors than their classical counterparts. Fortunately, it is possible to redundantly encode information in several entangled qubits, making it robust to decoherence and control imprecision with quantum error correction. I studied one possible physical implementation for quantum computing, employing the ground and first excited quantum states of a superconducting electrical circuit as a quantum bit. These ``transmon'' qubits are dispersively coupled to a superconducting resonator used for readout, control, and qubit-qubit coupling in the cavity quantum electrodynamics (cQED) architecture. In this talk I will give an general introduction to quantum computation and the superconducting technology that seeks to achieve it before explaining some of the specific results reported in my thesis. One major component is that of the first realization of three-qubit quantum error correction in a solid state device, where we encode one logical quantum bit in three entangled physical qubits and detect and correct phase- or bit-flip errors using a three-qubit Toffoli gate. My thesis is available at arXiv:1311.6759.
Rig site computer optimizes bit weight
Enen, J.; Callas, N.P.; Sullivan, W.
1984-02-13
A new tool has been developed to optimize the factors which control hole angle so faster drilling rates can be achieved. A computer program determines best stabilizer placement to prevent sacrifice of bit weight. It also learns from the last bit run and corrects itself. The program can quickly evaluate the angle build or drop characteristics of a bottom hole assembly (BHA) and compare it with the well plan. A corollary program evaluates casing centralization and stand off. These techniques can save drilling time and money in several circumstances. Whenever time is lost in straight hole drilling because of low bit weight for angle control, the program suggests a better BHA and higher weights. In directional drilling, it finds the fastest approach through one or more targets, again at the highest practical bit weight. In both instances, weight and rpm are designed for the formation drillability; BHA is designed to control angle under those specific conditions. This in effect frees up incremental bit weight without undue risk of crooked hole.
NASA Technical Reports Server (NTRS)
Noble, Viveca K.
1993-01-01
There are various elements such as radio frequency interference (RFI) which may induce errors in data being transmitted via a satellite communication link. When a transmission is affected by interference or other error-causing elements, the transmitted data becomes indecipherable. It becomes necessary to implement techniques to recover from these disturbances. The objective of this research is to develop software which simulates error control circuits and evaluate the performance of these modules in various bit error rate environments. The results of the evaluation provide the engineer with information which helps determine the optimal error control scheme. The Consultative Committee for Space Data Systems (CCSDS) recommends the use of Reed-Solomon (RS) and convolutional encoders and Viterbi and RS decoders for error correction. The use of forward error correction techniques greatly reduces the received signal to noise needed for a certain desired bit error rate. The use of concatenated coding, e.g. inner convolutional code and outer RS code, provides even greater coding gain. The 16-bit cyclic redundancy check (CRC) code is recommended by CCSDS for error detection.
NASA Astrophysics Data System (ADS)
Noble, Viveca K.
1993-11-01
There are various elements such as radio frequency interference (RFI) which may induce errors in data being transmitted via a satellite communication link. When a transmission is affected by interference or other error-causing elements, the transmitted data becomes indecipherable. It becomes necessary to implement techniques to recover from these disturbances. The objective of this research is to develop software which simulates error control circuits and evaluate the performance of these modules in various bit error rate environments. The results of the evaluation provide the engineer with information which helps determine the optimal error control scheme. The Consultative Committee for Space Data Systems (CCSDS) recommends the use of Reed-Solomon (RS) and convolutional encoders and Viterbi and RS decoders for error correction. The use of forward error correction techniques greatly reduces the received signal to noise needed for a certain desired bit error rate. The use of concatenated coding, e.g. inner convolutional code and outer RS code, provides even greater coding gain. The 16-bit cyclic redundancy check (CRC) code is recommended by CCSDS for error detection.
NASA Technical Reports Server (NTRS)
Montesano, P. M.; Cook, B. D.; Sun, G.; Simard, M.; Zhang, Z.; Nelson, R. F.; Ranson, K. J.; Lutchke, S.; Blair, J. B.
2012-01-01
The synergistic use of active and passive remote sensing (i.e., data fusion) demonstrates the ability of spaceborne light detection and ranging (LiDAR), synthetic aperture radar (SAR) and multispectral imagery for achieving the accuracy requirements of a global forest biomass mapping mission. This data fusion approach also provides a means to extend 3D information from discrete spaceborne LiDAR measurements of forest structure across scales much larger than that of the LiDAR footprint. For estimating biomass, these measurements mix a number of errors including those associated with LiDAR footprint sampling over regional - global extents. A general framework for mapping above ground live forest biomass (AGB) with a data fusion approach is presented and verified using data from NASA field campaigns near Howland, ME, USA, to assess AGB and LiDAR sampling errors across a regionally representative landscape. We combined SAR and Landsat-derived optical (passive optical) image data to identify forest patches, and used image and simulated spaceborne LiDAR data to compute AGB and estimate LiDAR sampling error for forest patches and 100m, 250m, 500m, and 1km grid cells. Forest patches were delineated with Landsat-derived data and airborne SAR imagery, and simulated spaceborne LiDAR (SSL) data were derived from orbit and cloud cover simulations and airborne data from NASA's Laser Vegetation Imaging Sensor (L VIS). At both the patch and grid scales, we evaluated differences in AGB estimation and sampling error from the combined use of LiDAR with both SAR and passive optical and with either SAR or passive optical alone. This data fusion approach demonstrates that incorporating forest patches into the AGB mapping framework can provide sub-grid forest information for coarser grid-level AGB reporting, and that combining simulated spaceborne LiDAR with SAR and passive optical data are most useful for estimating AGB when measurements from LiDAR are limited because they minimized
NASA Technical Reports Server (NTRS)
Vo, Q. D.
1984-01-01
A program which was written to simulate Real Time Minimal-Byte-Error Probability (RTMBEP) decoding of full unit-memory (FUM) convolutional codes on a 3-bit quantized AWGN channel is described. This program was used to compute the symbol-error probability of FUM codes and to determine the signal to noise (SNR) required to achieve a bit error rate (BER) of 10 to the minus 6th power for corresponding concatenated systems. A (6,6/30) FUM code, 6-bit Reed-Solomon code combination was found to achieve the required BER at a SNR of 1.886 dB. The RTMBEP algorithm was then modified for decoding partial unit-memory (PUM) convolutional codes. A simulation program was also written to simulate the symbol-error probability of these codes.
Drilling bits optimized for the Paris basin
Vennin, H.C. Pouyastruc )
1989-07-31
Paris basin wells have been successfully drilled using steel-body bits with stud-type cutters. These bits offer the possibility of optimizing the bit-face based on the strata to be drilled, as well as allowing replacement of worn cutters. This article discusses: bit manufacturing; bit repair; optimizing bits; hydraulics.
Short, L.W. Jr.; Barr, J.D.
1987-04-28
A drag-type drill bit is described comprising: a bit body having an operating end face; and a multiplicity of superhard cutting elements interlocked to the body. The cutting elements define a multiplicity of cutting areas dispersed over the operating end face of the bit body in a pattern adapted to cause the cutting areas to cut an earth formation to a desired three-dimensional profile as the bit body is rotated, the cutting areas having back rake angles which become more negative with distance from the profile.
Simultaneous message framing and error detection
NASA Technical Reports Server (NTRS)
Frey, A. H., Jr.
1968-01-01
Circuitry simultaneously inserts message framing information and detects noise errors in binary code data transmissions. Separate message groups are framed without requiring both framing bits and error-checking bits, and predetermined message sequence are separated from other message sequences without being hampered by intervening noise.
Drill bit assembly for releasably retaining a drill bit cutter
Glowka, David A.; Raymond, David W.
2002-01-01
A drill bit assembly is provided for releasably retaining a polycrystalline diamond compact drill bit cutter. Two adjacent cavities formed in a drill bit body house, respectively, the disc-shaped drill bit cutter and a wedge-shaped cutter lock element with a removable fastener. The cutter lock element engages one flat surface of the cutter to retain the cutter in its cavity. The drill bit assembly thus enables the cutter to be locked against axial and/or rotational movement while still providing for easy removal of a worn or damaged cutter. The ability to adjust and replace cutters in the field reduces the effect of wear, helps maintains performance and improves drilling efficiency.
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Positional Information, in bits
NASA Astrophysics Data System (ADS)
Dubuis, Julien; Bialek, William; Wieschaus, Eric; Gregor, Thomas
2010-03-01
Pattern formation in early embryonic development provides an important testing ground for ideas about the structure and dynamics of genetic regulatory networks. Spatial variations in the concentration of particular transcription factors act as ``morphogens,'' driving more complex patterns of gene expression that in turn define cell fates, which must be appropriate to the physical location of the cells in the embryo. Thus, in these networks, the regulation of gene expression serves to transmit and process ``positional information.'' Here, using the early Drosophila embryo as a model system, we measure the amount of positional information carried by a group of four genes (the gap genes Hunchback, Kr"uppel, Giant and Knirps) that respond directly to the primary maternal morphogen gradients. We find that the information carried by individual gap genes is much larger than one bit, so that their spatial patterns provide much more than the location of an ``expression boundary.'' Preliminary data indicate that, taken together these genes provide enough information to specify the location of every row of cells along the embryo's anterior-posterior axis.
Experimental unconditionally secure bit commitment
NASA Astrophysics Data System (ADS)
Liu, Yang; Cao, Yuan; Curty, Marcos; Liao, Sheng-Kai; Wang, Jian; Cui, Ke; Li, Yu-Huai; Lin, Ze-Hong; Sun, Qi-Chao; Li, Dong-Dong; Zhang, Hong-Fei; Zhao, Yong; Chen, Teng-Yun; Peng, Cheng-Zhi; Zhang, Qiang; Cabello, Adan; Pan, Jian-Wei
2014-03-01
Quantum physics allows unconditionally secure communication between parties that trust each other. However, when they do not trust each other such as in the bit commitment, quantum physics is not enough to guarantee security. Only when relativistic causality constraints combined, the unconditional secure bit commitment becomes feasible. Here we experimentally implement a quantum bit commitment with relativistic constraints that offers unconditional security. The commitment is made through quantum measurements in two quantum key distribution systems in which the results are transmitted via free-space optical communication to two agents separated with more than 20 km. Bits are successfully committed with less than 5 . 68 ×10-2 cheating probability. This provides an experimental proof of unconditional secure bit commitment and demonstrates the feasibility of relativistic quantum communication.
Extremely Low Bit-Rate Nearest Neighbor Search Using a Set Compression Tree.
Arandjelović, Relja; Zisserman, Andrew
2014-12-01
The goal of this work is a data structure to support approximate nearest neighbor search on very large scale sets of vector descriptors. The criteria we wish to optimize are: (i) that the memory footprint of the representation should be very small (so that it fits into main memory); and (ii) that the approximation of the original vectors should be accurate. We introduce a novel encoding method, named a Set Compression Tree (SCT), that satisfies these criteria. It is able to accurately compress 1 million descriptors using only a few bits per descriptor. The large compression rate is achieved by not compressing on a per-descriptor basis, but instead by compressing the set of descriptors jointly. We describe the encoding, decoding and use for nearest neighbor search, all of which are quite straightforward to implement. The method, tested on standard benchmarks (SIFT1M and 80 Million Tiny Images), achieves superior performance to a number of state-of-the-art approaches, including Product Quantization, Locality Sensitive Hashing, Spectral Hashing, and Iterative Quantization. For example, SCT has a lower error using 5 bits than any of the other approaches, even when they use 16 or more bits per descriptor. We also include a comparison of all the above methods on the standard benchmarks. PMID:26353147
Adams, Diane L.; Norman, Helen; Burroughs, Valentine J.
2002-01-01
Medical practice today, more than ever before, places greater demands on physicians to see more patients, provide more complex medical services and adhere to stricter regulatory rules, leaving little time for coding and billing. Yet, the need to adequately document medical records, appropriately apply billing codes and accurately charge insurers for medical services is essential to the medical practice's financial condition. Many physicians rely on office staff and billing companies to process their medical bills without ever reviewing the bills before they are submitted for payment. Some physicians may not be receiving the payment they deserve when they do not sufficiently oversee the medical practice's coding and billing patterns. This article emphasizes the importance of monitoring and auditing medical record documentation and coding application as a strategy for achieving compliance and reducing billing errors. When medical bills are submitted with missing and incorrect information, they may result in unpaid claims and loss of revenue to physicians. Addressing Medical Audits, Part I--A Strategy for Achieving Compliance--CMS, JCAHO, NCQA, published January 2002 in the Journal of the National Medical Association, stressed the importance of preparing the medical practice for audits. The article highlighted steps the medical practice can take to prepare for audits and presented examples of guidelines used by regulatory agencies to conduct both medical and financial audits. The Medicare Integrity Program was cited as an example of guidelines used by regulators to identify coding errors during an audit and deny payment to providers when improper billing occurs. For each denied claim, payments owed to the medical practice are are also denied. Health care is, no doubt, a costly endeavor for health care providers, consumers and insurers. The potential risk to physicians for improper billing may include loss of revenue, fraud investigations, financial sanction
Inadvertently programmed bits in Samsung 128 Mbit flash devices: a flaky investigation
NASA Technical Reports Server (NTRS)
Swift, G.
2002-01-01
JPL's X2000 avionics design pioneers new territory by specifying a non-volatile memory (NVM) board based on flash memories. The Samsung 128Mb device chosen was found to demonstrate bit errors (mostly program disturbs) and block-erase failures that increase with cycling. Low temperature, certain pseudo- random patterns, and, probably, higher bias increase the observable bit errors. An experiment was conducted to determine the wearout dependence of the bit errors to 100k cycles at cold temperature using flight-lot devices (some pre-irradiated). The results show an exponential growth rate, a wide part-to-part variation, and some annealing behavior.
A VLSI single chip 8-bit finite field multiplier
NASA Technical Reports Server (NTRS)
Deutsch, L. J.; Shao, H. M.; Hsu, I. S.; Truong, T. K.
1985-01-01
A Very Large Scale Integration (VLSI) architecture and layout for an 8-bit finite field multiplier is described. The algorithm used in this design was developed by Massey and Omura. A normal basis representation of finite field elements is used to reduce the multiplication complexity. It is shown that a drastic improvement was achieved in this design. This multiplier will be used intensively in the implementation of an 8-bit Reed-Solomon decoder and in many other related projects.
Experimental unconditionally secure bit commitment.
Liu, Yang; Cao, Yuan; Curty, Marcos; Liao, Sheng-Kai; Wang, Jian; Cui, Ke; Li, Yu-Huai; Lin, Ze-Hong; Sun, Qi-Chao; Li, Dong-Dong; Zhang, Hong-Fei; Zhao, Yong; Chen, Teng-Yun; Peng, Cheng-Zhi; Zhang, Qiang; Cabello, Adán; Pan, Jian-Wei
2014-01-10
Quantum physics allows for unconditionally secure communication between parties that trust each other. However, when the parties do not trust each other such as in the bit commitment scenario, quantum physics is not enough to guarantee security unless extra assumptions are made. Unconditionally secure bit commitment only becomes feasible when quantum physics is combined with relativistic causality constraints. Here we experimentally implement a quantum bit commitment protocol with relativistic constraints that offers unconditional security. The commitment is made through quantum measurements in two quantum key distribution systems in which the results are transmitted via free-space optical communication to two agents separated with more than 20 km. The security of the protocol relies on the properties of quantum information and relativity theory. In each run of the experiment, a bit is successfully committed with less than 5.68×10(-2) cheating probability. This demonstrates the experimental feasibility of quantum communication with relativistic constraints. PMID:24483878
Experimental Unconditionally Secure Bit Commitment
NASA Astrophysics Data System (ADS)
Liu, Yang; Cao, Yuan; Curty, Marcos; Liao, Sheng-Kai; Wang, Jian; Cui, Ke; Li, Yu-Huai; Lin, Ze-Hong; Sun, Qi-Chao; Li, Dong-Dong; Zhang, Hong-Fei; Zhao, Yong; Chen, Teng-Yun; Peng, Cheng-Zhi; Zhang, Qiang; Cabello, Adán; Pan, Jian-Wei
2014-01-01
Quantum physics allows for unconditionally secure communication between parties that trust each other. However, when the parties do not trust each other such as in the bit commitment scenario, quantum physics is not enough to guarantee security unless extra assumptions are made. Unconditionally secure bit commitment only becomes feasible when quantum physics is combined with relativistic causality constraints. Here we experimentally implement a quantum bit commitment protocol with relativistic constraints that offers unconditional security. The commitment is made through quantum measurements in two quantum key distribution systems in which the results are transmitted via free-space optical communication to two agents separated with more than 20 km. The security of the protocol relies on the properties of quantum information and relativity theory. In each run of the experiment, a bit is successfully committed with less than 5.68×10-2 cheating probability. This demonstrates the experimental feasibility of quantum communication with relativistic constraints.
Optimal encryption of quantum bits
Boykin, P. Oscar; Roychowdhury, Vwani
2003-04-01
We show that 2n random classical bits are both necessary and sufficient for encrypting any unknown state of n quantum bits in an informationally secure manner. We also characterize the complete set of optimal protocols in terms of a set of unitary operations that comprise an orthonormal basis in a canonical inner product space. Moreover, a connection is made between quantum encryption and quantum teleportation that allows for a different proof of optimality of teleportation.
Simplified 2-bit photonic digital-to-analog conversion unit based on polarization multiplexing
NASA Astrophysics Data System (ADS)
Zhang, Fangzheng; Gao, Bindong; Ge, Xiaozhong; Pan, Shilong
2016-03-01
A 2-bit photonic digital-to-analog conversion unit is proposed and demonstrated based on polarization multiplexing. The proposed 2-bit digital-to-analog converter (DAC) unit is realized by optical intensity weighting and summing, and its complexity is greatly reduced compared with the traditional 2-bit photonic DACs. Performance of the proposed 2-bit DAC unit is experimentally investigated. The established 2-bit DAC unit achieves a good linear transfer function, and the effective number of bits is calculated to be 1.3. Based on the proposed 2-bit DAC unit, two DAC structures with higher (>2) bit resolutions are proposed and discussed, and the system complexity is expected to be reduced by half by using the proposed technique.
String bit models for superstring
Bergman, O.; Thorn, C.B.
1995-12-31
The authors extend the model of string as a polymer of string bits to the case of superstring. They mainly concentrate on type II-B superstring, with some discussion of the obstacles presented by not II-B superstring, together with possible strategies for surmounting them. As with previous work on bosonic string work within the light-cone gauge. The bit model possesses a good deal less symmetry than the continuous string theory. For one thing, the bit model is formulated as a Galilei invariant theory in (D {minus} 2) + 1 dimensional space-time. This means that Poincare invariance is reduced to the Galilei subgroup in D {minus} 2 space dimensions. Naturally the supersymmetry present in the bit model is likewise dramatically reduced. Continuous string can arise in the bit models with the formation of infinitely long polymers of string bits. Under the right circumstances (at the critical dimension) these polymers can behave as string moving in D dimensional space-time enjoying the full N = 2 Poincare supersymmetric dynamics of type II-B superstring.
String bit models for superstring
Bergman, O.; Thorn, C.B.
1995-11-15
We extend the model of string as a polymer of string bits to the case of superstring. We mainly concentrate on type II-B superstring, with some discussion of the obstacles presented by not II-B superstring, together with possible strategies for surmounting them. As with previous work on bosonic string we work within the light-cone gauge. The bit model possesses a good deal less symmetry than the continuous string theory. For one thing, the bit model is formulated as a Galilei-invariant theory in [({ital D}{minus}2)+1]-dimensional space-time. This means that Poincare invariance is reduced to the Galilei subgroup in {ital D}{minus}2 space dimensions. Naturally the supersymmetry present in the bit model is likewise dramatically reduced. Continuous string can arise in the bit models with the formation of infinitely long polymers of string bits. Under the right circumstances (at the critical dimension) these polymers can behave as string moving in {ital D}-dimensional space-time enjoying the full {ital N}=2 Poincare supersymmetric dynamics of type II-B superstring.
Modeling and analysis of stick-slip and bit bounce in oil well drillstrings equipped with drag bits
NASA Astrophysics Data System (ADS)
Kamel, Jasem M.; Yigit, Ahmet S.
2014-12-01
Rotary drilling systems equipped with drag bits or fixed cutter bits (also called PDC), used for drilling deep boreholes for the production and the exploration of oil and natural gas, often suffer from severe vibrations. These vibrations are detrimental to the bit and the drillstring causing different failures of equipment (e.g., twist-off, abrasive wear of tubulars, bit damage), and inefficiencies in the drilling operation (reduction of the rate of penetration (ROP)). Despite extensive research conducted in the last several decades, there is still a need to develop a consistent model that adequately captures all phenomena related to drillstring vibrations such as nonlinear cutting and friction forces at the bit/rock formation interface, drive system characteristics and coupling between various motions. In this work, a physically consistent nonlinear model for the axial and torsional motions of a rotating drillstring equipped with a drag bit is proposed. A more realistic cutting and contact model is used to represent bit/rock formation interaction at the bit. The dynamics of both drive systems for rotary and translational motions of the drillstring, including the hoisting system are also considered. In this model, the rotational and translational motions of the bit are obtained as a result of the overall dynamic behavior rather than prescribed functions or constants. The dynamic behavior predicted by the proposed model qualitatively agree well with field observations and published theoretical results. The effects of various operational parameters on the dynamic behavior are investigated with the objective of achieving a smooth and efficient drilling. The results show that with proper choice of operational parameters, it may be possible to minimize the effects of stick-slip and bit-bounce and increase the ROP. Therefore, it is expected that the results will help reduce the time spent in drilling process and costs incurred due to severe vibrations and consequent
NASA Technical Reports Server (NTRS)
Wilson, E.
2001-01-01
The Jet Propulsion Laboratory's (JPL) Advanced Multi-Mission Operations System (AMMOS) system processes data received from deep-space spacecraft, where error rates are high, bit rates are low, and every bit is precious. Frame synchronization and data extraction as performed by AMMOS enhanced data acquisition and reliability for maximum data return and validity.
De Groot, A.J.
1989-01-01
In this dissertation the author considered the design of bit - level systolic arrays where the basic computational unit consists of a simple one - bit logic unit, so that the systolic process is carried out at the level of individual bits. In order to pursue the foregoing research, several areas have been studied. First, the concept of systolic processing has been investigated. Several important algorithms were investigated and put into systolic form using graph-theoretic methods. The bit-level, word-level and block-level systolic arrays which have been designed for these algorithms exhibit linear speedup with respect to the number of processors and exhibit efficiency close to 100%, even with low interprocessor communication bandwidth. Block-level systolic arrays deal with blocks of data with block-level operations and communications. Block-level systolic arrays improve cell efficiency and are more efficient than their word-level counterparts. A comparison of bit-level, word-level and block-level systolic arrays was performed. In order to verify the foregoing theory and analysis a systolic processor called the SPRINT was developed to provide and environment where bit-level, word-level and block-level systolic algorithms could be confirmed by direct implementation rather than by computer simulation. The SPRINT is a supercomputer class, 64-element multiprocessor with a reconfigurable interconnection network. The theory has been confirmed by the execution on the SPRINT of the bit-level, word-level, and block-level systolic algorithms presented in the dissertation.
Drill bit method and apparatus
Davis, K.
1986-08-19
This patent describes a drill bit having a lower cutting face which includes a plurality of stud assemblies radially spaced from a longitudinal axial centerline of the bit, each stud assembly being mounted within a stud receiving socket which is formed in the bit cutting face. The method of removing the stud assemblies from the sockets of the bit face consists of: forming a socket passageway along the longitudinal axial centerline of the stud receiving socket and extending the passageway rearwardly of the socket; forming a blind passageway which extends from the bit cutting face into the bit body, and into intersecting relationship respective to the socket passageway; while arranging the socket passageway and the blind passageway laterally respective to one another; forming a wedge face on one side of a tool, forming a support post which has one side inclined to receive the wedge face of the tool thereagainst; forcing a ball to move from the cutting face of the bit, into the blind passageway, onto the support post, then into the socket passageway, and into abutting engagement with a rear end portion of the stud assembly; placing the wedge face against the side of the ball which is opposed to the stud assembly; forcing the tool to move into the blind passageway while part of the tool engages the blind passageway and the wedge face engages the ball and thereby forces the ball to move in a direction away from the blind passageway; applying sufficient force to the tool to cause the ball to engage the stud assembly with sufficient force to be moved outwardly in a direction away from the socket, thereby releasing the stud assembly from the socket.
Drill bit and method of renewing drill bit cutting face
Davis, K.
1987-04-07
This patent describes a drill bit having a lower formation engaging face which includes sockets formed therein, a stud assembly mounted in each socket. The method is described of removing the stud assemblies from the bit face comprises: placing a seal means about each stud assembly so that a stud assembly can sealingly reciprocate within a socket with a piston-like action; forming a reduced diameter passageway which extends rearwardly from communication with each socket to the exterior of the bit; flowing fluid into the passageway, thereby exerting fluid pressure against the rear end of the stud assembly; applying sufficient pressure to the fluid within the passageway to produce a pressure differential across the stud assembly to force the stud assembly to move outwardly in a direction away from the socket, thereby releasing the stud assembly from the socket.
Image data compression having minimum perceptual error
NASA Technical Reports Server (NTRS)
Watson, Andrew B. (Inventor)
1995-01-01
A method for performing image compression that eliminates redundant and invisible image components is described. The image compression uses a Discrete Cosine Transform (DCT) and each DCT coefficient yielded by the transform is quantized by an entry in a quantization matrix which determines the perceived image quality and the bit rate of the image being compressed. The present invention adapts or customizes the quantization matrix to the image being compressed. The quantization matrix comprises visual masking by luminance and contrast techniques and by an error pooling technique all resulting in a minimum perceptual error for any given bit rate, or minimum bit rate for a given perceptual error.
Bit by bit: the Darwinian basis of life.
Joyce, Gerald F
2012-01-01
All known examples of life belong to the same biology, but there is increasing enthusiasm among astronomers, astrobiologists, and synthetic biologists that other forms of life may soon be discovered or synthesized. This enthusiasm should be tempered by the fact that the probability for life to originate is not known. As a guiding principle in parsing potential examples of alternative life, one should ask: How many heritable "bits" of information are involved, and where did they come from? A genetic system that contains more bits than the number that were required to initiate its operation might reasonably be considered a new form of life. PMID:22589698
A unified framework for optimal multiple video object bit allocation
NASA Astrophysics Data System (ADS)
Chen, Zhenzhong; Ngan, King Ngi
2005-07-01
MPEG-4 supports object-level video coding. It is a challenge to design an optimal bit allocation strategy which considers not only how to distribute bits among multiple video objects (MVO's) but also how to achieve optimization between the texture and shape information. In this paper, we present a uniform framework for optimal multiple video object bit allocation in MPEG-4. We combine the rate-distortion (R-D) models for the texture and shape information of arbitrarily shaped video objects to develop the joint texture-shape rate-distortion models. The dynamic programming (DP) technique is applied to optimize the bit allocation for the multiple video objects. The simulation results demonstrate that the proposed joint texture-shape optimization algorithm outperforms the MPEG-4 verification model on the decoded picture quality.
Analysis of transmission error effects on the transfer of real-time simulation data
NASA Technical Reports Server (NTRS)
Credeur, L.
1977-01-01
An analysis was made to determine the effect of transmission errors on the quality of data transferred from the Terminal Area Air Traffic Model to a remote site. Data formating schemes feasible within the operational constraints of the data link were proposed and their susceptibility to both random bit error and to noise burst were investigated. It was shown that satisfactory reliability is achieved by a scheme formating the simulation output into three data blocks which has the priority data triply redundant in the first block in addition to having a retransmission priority on that first block when it is received in error.
A bit serial sequential circuit
NASA Technical Reports Server (NTRS)
Hu, S.; Whitaker, S.
1990-01-01
Normally a sequential circuit with n state variables consists of n unique hardware realizations, one for each state variable. All variables are processed in parallel. This paper introduces a new sequential circuit architecture that allows the state variables to be realized in a serial manner using only one next state logic circuit. The action of processing the state variables in a serial manner has never been addressed before. This paper presents a general design procedure for circuit construction and initialization. Utilizing pass transistors to form the combinational next state forming logic in synchronous sequential machines, a bit serial state machine can be realized with a single NMOS pass transistor network connected to shift registers. The bit serial state machine occupies less area than other realizations which perform parallel operations. Moreover, the logical circuit of the bit serial state machine can be modified by simply changing the circuit input matrix to develop an adaptive state machine.
NASA Astrophysics Data System (ADS)
Smarandache, Florentin; Christianto, V.
2011-03-01
Mu-bit is defined here as `multi-space bit'. It is different from the standard meaning of bit in conventional computation, because in Smarandache's multispace theory (also spelt multi-space) the bit is created simultaneously in many subspaces (that form together a multi-space). This new `bit' term is different from multi-valued-bit already known in computer technology, for example as MVLong. This new concept is also different from qu-bit from quantum computation terminology. We know that using quantum mechanics logic we could introduce new way of computation with `qubit' (quantum bit), but the logic remains Neumann. Now, from the viewpoint of m-valued multi-space logic, we introduce a new term: `mu-bit' (from `multi-space bit).
NASA Technical Reports Server (NTRS)
Noble, Viveca K.
1994-01-01
When data is transmitted through a noisy channel, errors are produced within the data rendering it indecipherable. Through the use of error control coding techniques, the bit error rate can be reduced to any desired level without sacrificing the transmission data rate. The Astrionics Laboratory at Marshall Space Flight Center has decided to use a modular, end-to-end telemetry data simulator to simulate the transmission of data from flight to ground and various methods of error control. The simulator includes modules for random data generation, data compression, Consultative Committee for Space Data Systems (CCSDS) transfer frame formation, error correction/detection, error generation and error statistics. The simulator utilizes a concatenated coding scheme which includes CCSDS standard (255,223) Reed-Solomon (RS) code over GF(2(exp 8)) with interleave depth of 5 as the outermost code, (7, 1/2) convolutional code as an inner code and CCSDS recommended (n, n-16) cyclic redundancy check (CRC) code as the innermost code, where n is the number of information bits plus 16 parity bits. The received signal-to-noise for a desired bit error rate is greatly reduced through the use of forward error correction techniques. Even greater coding gain is provided through the use of a concatenated coding scheme. Interleaving/deinterleaving is necessary to randomize burst errors which may appear at the input of the RS decoder. The burst correction capability length is increased in proportion to the interleave depth. The modular nature of the simulator allows for inclusion or exclusion of modules as needed. This paper describes the development and operation of the simulator, the verification of a C-language Reed-Solomon code, and the possibility of using Comdisco SPW(tm) as a tool for determining optimal error control schemes.
NASA Astrophysics Data System (ADS)
Noble, Viveca K.
1994-10-01
When data is transmitted through a noisy channel, errors are produced within the data rendering it indecipherable. Through the use of error control coding techniques, the bit error rate can be reduced to any desired level without sacrificing the transmission data rate. The Astrionics Laboratory at Marshall Space Flight Center has decided to use a modular, end-to-end telemetry data simulator to simulate the transmission of data from flight to ground and various methods of error control. The simulator includes modules for random data generation, data compression, Consultative Committee for Space Data Systems (CCSDS) transfer frame formation, error correction/detection, error generation and error statistics. The simulator utilizes a concatenated coding scheme which includes CCSDS standard (255,223) Reed-Solomon (RS) code over GF(2(exp 8)) with interleave depth of 5 as the outermost code, (7, 1/2) convolutional code as an inner code and CCSDS recommended (n, n-16) cyclic redundancy check (CRC) code as the innermost code, where n is the number of information bits plus 16 parity bits. The received signal-to-noise for a desired bit error rate is greatly reduced through the use of forward error correction techniques. Even greater coding gain is provided through the use of a concatenated coding scheme. Interleaving/deinterleaving is necessary to randomize burst errors which may appear at the input of the RS decoder. The burst correction capability length is increased in proportion to the interleave depth. The modular nature of the simulator allows for inclusion or exclusion of modules as needed. This paper describes the development and operation of the simulator, the verification of a C-language Reed-Solomon code, and the possibility of using Comdisco SPW(tm) as a tool for determining optimal error control schemes.
Bond, J.W.
1988-01-01
Data-compression codes offer the possibility of improving the thruput of existing communication systems in the near term. This study was undertaken to determine if data-compression codes could be utilized to provide message compression in a channel with up to a 0.10-bit error rate. The data-compression capabilities of codes were investigated by estimating the average number of bits-per-character required to transmit narrative files. The performance of the codes in a channel with errors (a noisy channel) was investigated in terms of the average numbers of characters-decoded-in-error and of characters-printed-in-error-per-bit-error. Results were obtained by encoding four narrative files, which were resident on an IBM-PC and use a 58-character set. The study focused on Huffman codes and suffix/prefix comma-free codes. Other data-compression codes, in particular, block codes and some simple variants of block codes, are briefly discussed to place the study results in context. Comma-free codes were found to have the most-promising data compression because error propagation due to bit errors are limited to a few characters for these codes. A technique was found to identify a suffix/prefix comma-free code giving nearly the same data compressions as a Huffman code with much less error propagation than the Huffman codes. Greater data compression can be achieved through the use of this comma-free code word assignments based on conditioned probabilities of character occurrence.
Hondo, Toshinobu; Kawai, Yousuke; Toyoda, Michisato
2015-01-01
Rapid acquisition of time-of-flight (TOF) spectra from fewer acquisitions on average was investigated using the newly introduced 12-bit digitizer, Keysight model U5303A. This is expected to achieve a spectrum acquisition 32 times faster than the commonly used 8-bit digitizer for an equal signal-to-noise (S/N) ratio. Averaging fewer pulses improves the detection speed and chromatographic separation performance. However, increasing the analog-to-digital converter bit resolution for a high-frequency signal, such as a TOF spectrum, increases the system noise and requires the timing jitter (aperture error) to be minimized. We studied the relationship between the S/N ratio and the average number of acquisitions using U5303A and compared this with an 8-bit digitizer. The results show that the noise, measured as root-mean-square, decreases linearly to the square root of the average number of acquisitions without background subtraction, which means that almost no systematic noise existed in our signal bandwidth of interest (a few hundreds megahertz). In comparison, 8-bit digitizers that are commonly used in the market require 32 times more pulses with background subtraction. PMID:25906030
Error control techniques for satellite and space communications
NASA Technical Reports Server (NTRS)
Costello, D. J., Jr.
1986-01-01
High rate concatenated coding systems with trellis inner codes and Reed-Solomon (RS) outer codes for application in satellite communication systems are considered. Two types of inner codes are studied: high rate punctured binary convolutional codes which result in overall effective information rates between 1/2 and 1 bit per channel use; and bandwidth efficient signal space trellis codes which can achieve overall effective information rates greater than 1 bit per channel use. Channel capacity calculations with and without side information performed for the concatenated coding system. Concatenated coding schemes are investigated. In Scheme 1, the inner code is decoded with the Viterbi algorithm and the outer RS code performs error-correction only (decoding without side information). In scheme 2, the inner code is decoded with a modified Viterbi algorithm which produces reliability information along with the decoded output. In this algorithm, path metrics are used to estimate the entire information sequence, while branch metrics are used to provide the reliability information on the decoded sequence. This information is used to erase unreliable bits in the decoded output. An errors-and-erasures RS decoder is then used for the outer code. These two schemes are proposed for use on NASA satellite channels. Results indicate that high system reliability can be achieved with little or no bandwidth expansion.
High Capacity Reversible Watermarking for Audio by Histogram Shifting and Predicted Error Expansion
Wang, Fei; Chen, Zuo
2014-01-01
Being reversible, the watermarking information embedded in audio signals can be extracted while the original audio data can achieve lossless recovery. Currently, the few reversible audio watermarking algorithms are confronted with following problems: relatively low SNR (signal-to-noise) of embedded audio; a large amount of auxiliary embedded location information; and the absence of accurate capacity control capability. In this paper, we present a novel reversible audio watermarking scheme based on improved prediction error expansion and histogram shifting. First, we use differential evolution algorithm to optimize prediction coefficients and then apply prediction error expansion to output stego data. Second, in order to reduce location map bits length, we introduced histogram shifting scheme. Meanwhile, the prediction error modification threshold according to a given embedding capacity can be computed by our proposed scheme. Experiments show that this algorithm improves the SNR of embedded audio signals and embedding capacity, drastically reduces location map bits length, and enhances capacity control capability. PMID:25097883
... leave you alone. Reviewed by: Elana Pearl Ben-Joseph, MD Date reviewed: April 2013 For Teens For Kids For Parents MORE ON THIS TOPIC Hey! A Fire Ant Stung Me! Hey! A Scorpion Stung Me! Hey! A Black Widow Spider Bit Me! Hey! A Brown Recluse ...
... Here's Help White House Lunch Recipes Hey! A Mosquito Bit Me! KidsHealth > For Kids > Hey! A Mosquito ... español ¡Ay! ¡Me picó un mosquito! What's a Mosquito? A mosquito (say: mus-KEE-toe) is an ...
... Snowboarding, Skating Crushes What's a Booger? Hey! A Bedbug Bit Me! KidsHealth > For Kids > Hey! A Bedbug ... español ¡Ay! ¡Me picó una chinche! What a Bedbug Is A bedbug is a small (about the ...
Ultraspectral sounder data compression using a novel marker-based error-resilient arithmetic coder
NASA Astrophysics Data System (ADS)
Huang, Bormin; Sriraja, Y.; Wei, Shih-Chieh
2006-08-01
Entropy coding techniques aim to achieve the entropy of the source data by assigning variable-length codewords to symbols with the code lengths linked to the corresponding symbol probabilities. Entropy coders (e.g. Huffman coding, arithmetic coding), in one form or the other, are commonly used as the last stage in various compression schemes. While these variable-length coders provide better compression than fixed-length coders, they are vulnerable to transmission errors. Even a single bit error in the transmission process can cause havoc in the subsequent decoded stream. To cope with it, this research proposes a marker-based sentinel mechanism in entropy coding for error detection and recovery. We use arithmetic coding as an example to demonstrate this error-resilient technique for entropy coding. Experimental results on ultraspectral sounder data indicate that the marker-based error-resilient arithmetic coder provides remarkable robustness to correct transmission errors without significantly compromising the compression gains.
Takahashi, Koji; Matsui, Hideki; Nagashima, Tomotaka; Konishi, Tsuyoshi
2013-11-15
We demonstrate a resolution upgrade toward 6 bit optical quantization using a power-to-wavelength conversion without an increment of system parallelism. Expansion of a full-scale input range is employed in conjunction with reduction of a quantization step size with keeping a sampling-rate transparency characteristic over several 100 sGS/s. The effective number of bits is estimated to 5.74 bit, and the integral nonlinearity error and differential nonlinearity error are estimated to less than 1 least significant bit. PMID:24322152
Compact disk error measurements
NASA Technical Reports Server (NTRS)
Howe, D.; Harriman, K.; Tehranchi, B.
1993-01-01
The objectives of this project are as follows: provide hardware and software that will perform simple, real-time, high resolution (single-byte) measurement of the error burst and good data gap statistics seen by a photoCD player read channel when recorded CD write-once discs of variable quality (i.e., condition) are being read; extend the above system to enable measurement of the hard decision (i.e., 1-bit error flags) and soft decision (i.e., 2-bit error flags) decoding information that is produced/used by the Cross Interleaved - Reed - Solomon - Code (CIRC) block decoder employed in the photoCD player read channel; construct a model that uses data obtained via the systems described above to produce meaningful estimates of output error rates (due to both uncorrected ECC words and misdecoded ECC words) when a CD disc having specific (measured) error statistics is read (completion date to be determined); and check the hypothesis that current adaptive CIRC block decoders are optimized for pressed (DAD/ROM) CD discs. If warranted, do a conceptual design of an adaptive CIRC decoder that is optimized for write-once CD discs.
Priority-based error correction using turbo codes for compressed AIRS data
NASA Astrophysics Data System (ADS)
Gladkova, I.; Grossberg, M.; Grayver, E.; Olsen, D.; Nalli, N.; Wolf, W.; Zhou, L.; Goldberg, M.
2006-08-01
Errors due to wireless transmission can have an arbitrarily large impact on a compressed file. A single bit error appearing in the compressed file can propagate during a decompression procedure and destroy the entire granule. Such a loss is unacceptable since this data is critical for a range of applications, including weather prediction and emergency response planning. The impact of a bit error in the compressed granule is very sensitive to the error's location in the file. There is a natural hierarchy of compressed data in terms of impact on the final retrieval products. For the considered compression scheme, errors in some parts of the data yield no noticeable degradation in the final products. We formulate a priority scheme for the compressed data and present an error correction approach based on minimizing impact on the retrieval products. Forward error correction codes (e.g., turbo, LDPC) allow the tradeoff between error correction strength and file inflation (bandwidth expansion). We propose segmenting the compressed data based on its priority and applying different-strength FEC codes to different segments. In this paper we demonstrate that this approach can achieve negligible product degradation while maintaining an overall 3-to-1 compression ratio on the final file. We apply this to AIRS sounder data to demonstrate viability for the sounder on the next-generation GOES-R platform.
Stability of single skyrmionic bits
Hagemeister, J.; Romming, N.; von Bergmann, K.; Vedmedenko, E. Y.; Wiesendanger, R.
2015-01-01
The switching between topologically distinct skyrmionic and ferromagnetic states has been proposed as a bit operation for information storage. While long lifetimes of the bits are required for data storage devices, the lifetimes of skyrmions have not been addressed so far. Here we show by means of atomistic Monte Carlo simulations that the field-dependent mean lifetimes of the skyrmionic and ferromagnetic states have a high asymmetry with respect to the critical magnetic field, at which these lifetimes are identical. According to our calculations, the main reason for the enhanced stability of skyrmions is a different field dependence of skyrmionic and ferromagnetic activation energies and a lower attempt frequency of skyrmions rather than the height of energy barriers. We use this knowledge to propose a procedure for the determination of effective material parameters and the quantification of the Monte Carlo timescale from the comparison of theoretical and experimental data. PMID:26465211
Image Data Compression Having Minimum Perceptual Error
NASA Technical Reports Server (NTRS)
Watson, Andrew B. (Inventor)
1997-01-01
A method is presented for performing color or grayscale image compression that eliminates redundant and invisible image components. The image compression uses a Discrete Cosine Transform (DCT) and each DCT coefficient yielded by the transform is quantized by an entry in a quantization matrix which determines the perceived image quality and the bit rate of the image being compressed. The quantization matrix comprises visual masking by luminance and contrast technique all resulting in a minimum perceptual error for any given bit rate, or minimum bit rate for a given perceptual error.
Potter, Beth K; Chakraborty, Pranesh; Kronick, Jonathan B; Wilson, Kumanan; Coyle, Doug; Feigenbaum, Annette; Geraghty, Michael T; Karaceper, Maria D; Little, Julian; Mhanni, Aizeddin; Mitchell, John J; Siriwardena, Komudi; Wilson, Brenda J; Syrowatka, Ania
2013-06-01
Across all areas of health care, decision makers are in pursuit of what Berwick and colleagues have called the "triple aim": improving patient experiences with care, improving health outcomes, and managing health system impacts. This is challenging in a rare disease context, as exemplified by inborn errors of metabolism. There is a need for evaluative outcomes research to support effective and appropriate care for inborn errors of metabolism. We suggest that such research should consider interventions at both the level of the health system (e.g., early detection through newborn screening, programs to provide access to treatments) and the level of individual patient care (e.g., orphan drugs, medical foods). We have developed a practice-based evidence framework to guide outcomes research for inborn errors of metabolism. Focusing on outcomes across the triple aim, this framework integrates three priority themes: tailoring care in the context of clinical heterogeneity; a shift from "urgent care" to "opportunity for improvement"; and the need to evaluate the comparative effectiveness of emerging and established therapies. Guided by the framework, a new Canadian research network has been established to generate knowledge that will inform the design and delivery of health services for patients with inborn errors of metabolism and other rare diseases. PMID:23222662
Panel focuses on diamond shear bit care
Park, A.
1982-10-04
This article examines drilling parameters and marketability of Stratapax bits. Finds that core bits drill from 2 to 3 times faster than conventional diamond bits, thereby reducing filtrate invasion. Predicts that high speed drilling, downhole motors, deeper wells and slim hole drilling will mean greater Stratapax use.
Development of PDC Bits for Downhole Motors
Karasawa, H.; Ohno, T.
1995-01-01
To develop polycrystalline hamond compact (PDC) bits of the full-face type which can be applied to downhole motor drilling, drilling tests for granite and two types of andesite were conducted using bits with 98.43 and 142.88 mm diameters. The bits successfully drilled these types of rock at rotary speeds from 300 to 400 rpm.
A fast 2-bit digitizer for radio astronomy
NASA Astrophysics Data System (ADS)
Padin, Stephen; Ewing, Martin S.
1989-12-01
The design and performance details for a 2-bit digitizer operating at a 250-MHz clock rate are presented. The digitizer is part of a new correlator system for a three-element millimeter-wave interferometer. The performance of the digitizer circuit is analyzed in terms of threshold errors, indecision, sampling aperture width, and timing errors. For an input bandwidth of 125 MHz, digitizer distortion actually improves the sensitivity of the interferometer by about 0.3 percent but limits the dynamic range of the instrument to about 2 X 10 to the 3rd.
Bit by Bit: The Darwinian Basis of Life
Joyce, Gerald F.
2012-01-01
All known examples of life belong to the same biology, but there is increasing enthusiasm among astronomers, astrobiologists, and synthetic biologists that other forms of life may soon be discovered or synthesized. This enthusiasm should be tempered by the fact that the probability for life to originate is not known. As a guiding principle in parsing potential examples of alternative life, one should ask: How many heritable “bits” of information are involved, and where did they come from? A genetic system that contains more bits than the number that were required to initiate its operation might reasonably be considered a new form of life. PMID:22589698
Demonstration of low-power bit-interleaving TDM PON.
Van Praet, Christophe; Chow, Hungkei; Suvakovic, Dusan; Van Veen, Doutje; Dupas, Arnaud; Boislaigue, Roger; Farah, Robert; Lau, Man Fai; Galaro, Joseph; Qua, Gin; Anthapadmanabhan, N Prasanth; Torfs, Guy; Yin, Xin; Vetter, Peter
2012-12-10
A functional demonstration of bit-interleaving TDM downstream protocol for passive optical networks (Bi-PON) is reported. The proposed protocol presents a significant reduction in dynamic power consumption in the customer premise equipment over the conventional TDM protocol. It allows to select the relevant bits of all aggregated incoming data immediately after clock and data recovery (CDR) and, hence, allows subsequent hardware to run at much lower user rate. Comparison of experimental results of FPGA-based implementations of Bi-PON and XG-PON shows that more than 30x energy-savings in protocol processing is achievable. PMID:23262914
Smooth quality streaming with bit-plane labeling
NASA Astrophysics Data System (ADS)
Cho, Chuan-Yu; Chen, Hong-Sheng; Wang, Jia-Shung
2005-07-01
Bit-plane coding techniques have been proposed as an efficient way to achieve the goal of fine granularity scalability (FGS). Both in image and video coding standards such as JPEG 2000 and MPEG-4, bit-plane coding techniques have been utilized to code a universal bit-stream for various bandwidth applications. With the bit-plane coding, a bit-stream can be truncated according to the available bandwidth. Hence, the video quality can be very sensitive to the network bandwidth variation especially while streaming a video over the Internet or a wireless link. For overall human perception, a consistent and smooth quality video is much better than to have high video quality in just a short period but with highly quality variation in general. We classify the quality variation into two categories: inter-frame and intraframe quality variation. The inter-frame quality variation may cause by the constant bit rate coded (CBR) base layer video or the network bandwidth variation, while the intra-frame quality variation causes mainly by the various motion types. For example, moving objects are usually more difficult to be encoded. This paper focuses on the inter-frame quality variation because quality variation is more significant between frames than within a frame. An enhancement layer labeling algorithm is proposed to reduce the inter-frame quality variation, and a dynamic bit-plane truncation scheme is utilized to maintain the smooth streaming video quality. The proposed algorithm has no overhead in the decoder, and the experimental results portray that our proposed algorithm can greatly eliminate the inter-frame quality variation.
Quantifying the Impact of Single Bit Flips on Floating Point Arithmetic
Elliott, James J; Mueller, Frank; Stoyanov, Miroslav K; Webster, Clayton G
2013-08-01
In high-end computing, the collective surface area, smaller fabrication sizes, and increasing density of components have led to an increase in the number of observed bit flips. If mechanisms are not in place to detect them, such flips produce silent errors, i.e. the code returns a result that deviates from the desired solution by more than the allowed tolerance and the discrepancy cannot be distinguished from the standard numerical error associated with the algorithm. These phenomena are believed to occur more frequently in DRAM, but logic gates, arithmetic units, and other circuits are also susceptible to bit flips. Previous work has focused on algorithmic techniques for detecting and correcting bit flips in specific data structures, however, they suffer from lack of generality and often times cannot be implemented in heterogeneous computing environment. Our work takes a novel approach to this problem. We focus on quantifying the impact of a single bit flip on specific floating-point operations. We analyze the error induced by flipping specific bits in the most widely used IEEE floating-point representation in an architecture-agnostic manner, i.e., without requiring proprietary information such as bit flip rates and the vendor-specific circuit designs. We initially study dot products of vectors and demonstrate that not all bit flips create a large error and, more importantly, expected value of the relative magnitude of the error is very sensitive on the bit pattern of the binary representation of the exponent, which strongly depends on scaling. Our results are derived analytically and then verified experimentally with Monte Carlo sampling of random vectors. Furthermore, we consider the natural resilience properties of solvers based on the fixed point iteration and we demonstrate how the resilience of the Jacobi method for linear equations can be significantly improved by rescaling the associated matrix.
A cascaded coding scheme for error control
NASA Technical Reports Server (NTRS)
Kasami, T.; Lin, S.
1985-01-01
A cascaded coding scheme for error control was investigated. The scheme employs a combination of hard and soft decisions in decoding. Error performance is analyzed. If the inner and outer codes are chosen properly, extremely high reliability can be attained even for a high channel bit-error-rate. Some example schemes are studied which seem to be quite suitable for satellite down-link error control.
BIT BY BIT: A Game Simulating Natural Language Processing in Computers
ERIC Educational Resources Information Center
Kato, Taichi; Arakawa, Chuichi
2008-01-01
BIT BY BIT is an encryption game that is designed to improve students' understanding of natural language processing in computers. Participants encode clear words into binary code using an encryption key and exchange them in the game. BIT BY BIT enables participants who do not understand the concept of binary numbers to perform the process of…
Bit-synchronizer lock detector
NASA Technical Reports Server (NTRS)
Huey, D. C.; Itri, B. A.
1978-01-01
Circuit measures phase error that exists in phase-locked loop between clock signal recorded in data on magnetic tape and reconstructed clock signal. Circuit presents error as digital word that can be compared with predetermined threshold to indicate lock status. With simple alterations, circuit can also be used as phase detector.
Proper nozzle location, bit profile, and cutter arrangement affect PDC-bit performance significantly
Garcia-Gavito, D.; Azar, J.J.
1994-09-01
During the past 20 years, the drilling industry has looked to new technology to halt the exponentially increasing costs of drilling oil, gas, and geothermal wells. This technology includes bit design innovations to improve overall drilling performance and reduce drilling costs. These innovations include development of drag bits that use PDC cutters, also called PDC bits, to drill long, continuous intervals of soft to medium-hard formations more economically than conventional three-cone roller-cone bits. The cost advantage is the result of higher rates of penetration (ROP's) and longer bit life obtained with the PDC bits. An experimental study comparing the effects of polycrystalline-diamond-compact (PDC)-bit design features on the dynamic pressure distribution at the bit/rock interface was conducted on a full-scale drilling rig. Results showed that nozzle location, bit profile, and cutter arrangement are significant factors in PDC-bit performance.
Arbitrarily Long Relativistic Bit Commitment
NASA Astrophysics Data System (ADS)
Chakraborty, Kaushik; Chailloux, André; Leverrier, Anthony
2015-12-01
We consider the recent relativistic bit commitment protocol introduced by Lunghi et al. [Phys. Rev. Lett. 115, 030502 (2015)] and present a new security analysis against classical attacks. In particular, while the initial complexity of the protocol scales double exponentially with the commitment time, our analysis shows that the correct dependence is only linear. This has dramatic implications in terms of implementation: in particular, the commitment time can easily be made arbitrarily long, by only requiring both parties to communicate classically and perform efficient classical computation.
Ultraspectral sounder data compression using error-detecting reversible variable-length coding
NASA Astrophysics Data System (ADS)
Huang, Bormin; Ahuja, Alok; Huang, Hung-Lung; Schmit, Timothy J.; Heymann, Roger W.
2005-08-01
Nonreversible variable-length codes (e.g. Huffman coding, Golomb-Rice coding, and arithmetic coding) have been used in source coding to achieve efficient compression. However, a single bit error during noisy transmission can cause many codewords to be misinterpreted by the decoder. In recent years, increasing attention has been given to the design of reversible variable-length codes (RVLCs) for better data transmission in error-prone environments. RVLCs allow instantaneous decoding in both directions, which affords better detection of bit errors due to synchronization losses over a noisy channel. RVLCs have been adopted in emerging video coding standards--H.263+ and MPEG-4--to enhance their error-resilience capabilities. Given the large volume of three-dimensional data that will be generated by future space-borne ultraspectral sounders (e.g. IASI, CrIS, and HES), the use of error-robust data compression techniques will be beneficial to satellite data transmission. In this paper, we investigate a reversible variable-length code for ultraspectral sounder data compression, and present its numerical experiments on error propagation for the ultraspectral sounder data. The results show that the RVLC performs significantly better error containment than JPEG2000 Part 2.
Experimental Quantum Error Detection
Jin, Xian-Min; Yi, Zhen-Huan; Yang, Bin; Zhou, Fei; Yang, Tao; Peng, Cheng-Zhi
2012-01-01
Faithful transmission of quantum information is a crucial ingredient in quantum communication networks. To overcome the unavoidable decoherence in a noisy channel, to date, many efforts have been made to transmit one state by consuming large numbers of time-synchronized ancilla states. However, such huge demands of quantum resources are hard to meet with current technology and this restricts practical applications. Here we experimentally demonstrate quantum error detection, an economical approach to reliably protecting a qubit against bit-flip errors. Arbitrary unknown polarization states of single photons and entangled photons are converted into time bins deterministically via a modified Franson interferometer. Noise arising in both 10 m and 0.8 km fiber, which induces associated errors on the reference frame of time bins, is filtered when photons are detected. The demonstrated resource efficiency and state independence make this protocol a promising candidate for implementing a real-world quantum communication network. PMID:22953047
Quantum Error Correction with Biased Noise
NASA Astrophysics Data System (ADS)
Brooks, Peter
Quantum computing offers powerful new techniques for speeding up the calculation of many classically intractable problems. Quantum algorithms can allow for the efficient simulation of physical systems, with applications to basic research, chemical modeling, and drug discovery; other algorithms have important implications for cryptography and internet security. At the same time, building a quantum computer is a daunting task, requiring the coherent manipulation of systems with many quantum degrees of freedom while preventing environmental noise from interacting too strongly with the system. Fortunately, we know that, under reasonable assumptions, we can use the techniques of quantum error correction and fault tolerance to achieve an arbitrary reduction in the noise level. In this thesis, we look at how additional information about the structure of noise, or "noise bias," can improve or alter the performance of techniques in quantum error correction and fault tolerance. In Chapter 2, we explore the possibility of designing certain quantum gates to be extremely robust with respect to errors in their operation. This naturally leads to structured noise where certain gates can be implemented in a protected manner, allowing the user to focus their protection on the noisier unprotected operations. In Chapter 3, we examine how to tailor error-correcting codes and fault-tolerant quantum circuits in the presence of dephasing biased noise, where dephasing errors are far more common than bit-flip errors. By using an appropriately asymmetric code, we demonstrate the ability to improve the amount of error reduction and decrease the physical resources required for error correction. In Chapter 4, we analyze a variety of protocols for distilling magic states, which enable universal quantum computation, in the presence of faulty Clifford operations. Here again there is a hierarchy of noise levels, with a fixed error rate for faulty gates, and a second rate for errors in the distilled
Stability of single skyrmionic bits
NASA Astrophysics Data System (ADS)
Vedmedenko, Olena; Hagemeister, Julian; Romming, Niklas; von Bergmann, Kirsten; Wiesendanger, Roland
The switching between topologically distinct skyrmionic and ferromagnetic states has been proposed as a bit operation for information storage. While long lifetimes of the bits are required for data storage devices, the lifetimes of skyrmions have not been addressed so far. Here we show by means of atomistic Monte Carlo simulations that the field-dependent mean lifetimes of the skyrmionic and ferromagnetic states have a high asymmetry with respect to the critical magnetic field, at which these lifetimes are identical. According to our calculations, the main reason for the enhanced stability of skyrmions is a different field dependence of skyrmionic and ferromagnetic activation energies and a lower attempt frequency of skyrmions rather than the height of energy barriers. We use this knowledge to propose a procedure for the determination of effective material parameters and the quantification of the Monte Carlo timescale from the comparison of theoretical and experimental data. Financial support from the DFG in the framework of the SFB668 is acknowledged.
Multiple-error-correcting codes for improving the performance of optical matrix-vector processors.
Neifeld, M A
1995-04-01
I examine the use of Reed-Solomon multiple-error-correcting codes for enhancing the performance of optical matrix-vector processors. An optimal code rate of 0.75 is found, and n = 127 block-length codes are seen to increase the optical matrix dimension achievable by a factor of 2.0 for a required system bit-error rate of 10(-15). The optimal codes required for various matrix dimensions are determined. I show that single code word implementations are more efficient than those utilizing multiple code words. PMID:19859320
Performance analyses of subcarrier BPSK modulation over M turbulence channels with pointing errors
NASA Astrophysics Data System (ADS)
Ma, Shuang; Li, Ya-tian; Wu, Jia-bin; Geng, Tian-wen; Wu, Zhiyong
2016-05-01
An aggregated channel model is achieved by fitting the Weibull distribution, which includes the effects of atmospheric attenuation, M distributed atmospheric turbulence and nonzero boresight pointing errors. With this approximate channel model, the bit error rate ( BER) and the ergodic capacity of free-space optical (FSO) communication systems utilizing subcarrier binary phase-shift keying (BPSK) modulation are analyzed, respectively. A closed-form expression of BER is derived by using the generalized Gauss-Lagueree quadrature rule, and the bounds of ergodic capacity are discussed. Monte Carlo simulation is provided to confirm the validity of the BER expressions and the bounds of ergodic capacity.
Josephson 32-bit shift register
Yuh, P.F.; Yao, C.T.; Bradley, P. )
1991-03-01
This paper reports on a 32-bit shift register designed by edge-triggered gates tested with {plus minus}25% bias margin and {plus minus}81% input margin for the full array. Simulations have shown {plus minus}55% bias margin at 3.3 GHz and working up to a maximum frequency of 30 GHz with a junction current density of 2000A/cm{sup 2} although the shift register has only been tested up to 500 MHz, limited by instrumentation. This edge-triggered gate consisting of a pair of conventional Josephson logic gates in series has the advantages of wide margins, short reset time, and insensitivity to global parameter-variations.
Wu, Kesheng
2007-08-02
An index in a database system is a data structure that utilizes redundant information about the base data to speed up common searching and retrieval operations. Most commonly used indexes are variants of B-trees, such as B+-tree and B*-tree. FastBit implements a set of alternative indexes call compressed bitmap indexes. Compared with B-tree variants, these indexes provide very efficient searching and retrieval operations by sacrificing the efficiency of updating the indexes after the modification of an individual record. In addition to the well-known strengths of bitmap indexes, FastBit has a special strength stemming from the bitmap compression scheme used. The compression method is called the Word-Aligned Hybrid (WAH) code. It reduces the bitmap indexes to reasonable sizes and at the same time allows very efficient bitwise logical operations directly on the compressed bitmaps. Compared with the well-known compression methods such as LZ77 and Byte-aligned Bitmap code (BBC), WAH sacrifices some space efficiency for a significant improvement in operational efficiency. Since the bitwise logical operations are the most important operations needed to answer queries, using WAH compression has been shown to answer queries significantly faster than using other compression schemes. Theoretical analyses showed that WAH compressed bitmap indexes are optimal for one-dimensional range queries. Only the most efficient indexing schemes such as B+-tree and B*-tree have this optimality property. However, bitmap indexes are superior because they can efficiently answer multi-dimensional range queries by combining the answers to one-dimensional queries.
Error detection and correction unit with built-in self-test capability for spacecraft applications
NASA Technical Reports Server (NTRS)
Timoc, Constantin
1990-01-01
The objective of this project was to research and develop a 32-bit single chip Error Detection and Correction unit capable of correcting all single bit errors and detecting all double bit errors in the memory systems of a spacecraft. We designed the 32-bit EDAC (Error Detection and Correction unit) based on a modified Hamming code and according to the design specifications and performance requirements. We constructed a laboratory prototype (breadboard) which was converted into a fault simulator. The correctness of the design was verified on the breadboard using an exhaustive set of test cases. A logic diagram of the EDAC was delivered to JPL Section 514 on 4 Oct. 1988.
Coded modulation with unequal error protection
NASA Astrophysics Data System (ADS)
Wei, Lee-Fang
1993-10-01
It is always desirable to maintain communications in difficult situations, even though fewer messages can get across. This paper provides such capabilities for one-way broadcast media, such as the envisioned terrestrial broadcasting of digital high-definition television signals. In this television broadcasting, the data from video source encoders are not equally important. It is desirable that the important data be recovered by each receiver even under poor receiving conditions. Two approaches for providing such unequal error protection to different classes of data are presented. Power-efficient and bandwidth-efficient coded modulation is used in both approaches. The first approach is based on novel signal constellations with nonuniformly spaced signal points. The second uses time division multiplexing of different conventional coded modulation schemes. Both approaches can provide error protection for the important data to an extent that can hardly be achieved using conventional coded modulation with equal error protection. For modest amounts of important data, the first approach has, additionally, the potential of providing immunity from impulse noise through simple bit or signal-point interleaving.
Masking of errors in transmission of VAPC-coded speech
NASA Technical Reports Server (NTRS)
Cox, Neil B.; Froese, Edwin L.
1990-01-01
A subjective evaluation is provided of the bit error sensitivity of the message elements of a Vector Adaptive Predictive (VAPC) speech coder, along with an indication of the amenability of these elements to a popular error masking strategy (cross frame hold over). As expected, a wide range of bit error sensitivity was observed. The most sensitive message components were the short term spectral information and the most significant bits of the pitch and gain indices. The cross frame hold over strategy was found to be useful for pitch and gain information, but it was not beneficial for the spectral information unless severe corruption had occurred.
Improvement of PDC bit`s performance at high rotary speed
Karasawa, Hirokazu; Ohno, Tetsuji; Kobayashi, Hideo
1996-12-31
To develop polycrystalline diamond compact (PDC) full-face bits with high drilling efficiency, the effect of cutter diameter on the bit performance was investigated using 98.43 mm-dia bits. On the basis of this investigation, 142.88 mm-dia bits were fabricated and tested. The 142.88 mm-dia bits could drill through medium-hard to hard rocks at the rotary speeds from 256 to 400 rpm. Durability tests for granite using a 142.88 mm-dia bit revealed that it is necessary to improve the bit with regard to the arrangement of cutters and the number of cutters set on a bit body.
Photon-number-resolving detector with 10 bits of resolution
Jiang, Leaf A.; Dauler, Eric A.; Chang, Joshua T
2007-06-15
A photon-number-resolving detector with single-photon resolution is described and demonstrated. It has 10 bits of resolution, does not require cryogenic cooling, and is sensitive to near ir wavelengths. This performance is achieved by flood illuminating a 32x32 element In{sub x}Ga{sub 1-x}AsP Geiger-mode avalanche photodiode array that has an integrated counter and digital readout circuit behind each pixel.
Photon-number-resolving detector with 10bits of resolution
NASA Astrophysics Data System (ADS)
Jiang, Leaf A.; Dauler, Eric A.; Chang, Joshua T.
2007-06-01
A photon-number-resolving detector with single-photon resolution is described and demonstrated. It has 10bits of resolution, does not require cryogenic cooling, and is sensitive to near ir wavelengths. This performance is achieved by flood illuminating a 32×32 element InxGa1-xAsP Geiger-mode avalanche photodiode array that has an integrated counter and digital readout circuit behind each pixel.
Optimal multitone bit allocation for fixed-rate video transmission over ADSL
NASA Astrophysics Data System (ADS)
Antonini, Marc; Moureaux, Jean-Marie; Lecuire, Vincent
2002-01-01
In this paper we propose a novel approach for the bit allocation performed in an ADSL modulator. This new method is based on the observation that the transmission speed using ADSL strongly depends on the distance between the central office and the subscriber's side and does not permit real-time transmission for high bitrate video on long distances. The algorithm we develop takes into account the characteristics of a video sequence and distributes the channel error according to visual sensitivity. This method involves variable transmission Bit Error Rate.
Steganography forensics method for detecting least significant bit replacement attack
NASA Astrophysics Data System (ADS)
Wang, Xiaofeng; Wei, Chengcheng; Han, Xiao
2015-01-01
We present an image forensics method to detect least significant bit replacement steganography attack. The proposed method provides fine-grained forensics features by using the hierarchical structure that combines pixels correlation and bit-planes correlation. This is achieved via bit-plane decomposition and difference matrices between the least significant bit-plane and each one of the others. Generated forensics features provide the susceptibility (changeability) that will be drastically altered when the cover image is embedded with data to form a stego image. We developed a statistical model based on the forensics features and used least square support vector machine as a classifier to distinguish stego images from cover images. Experimental results show that the proposed method provides the following advantages. (1) The detection rate is noticeably higher than that of some existing methods. (2) It has the expected stability. (3) It is robust for content-preserving manipulations, such as JPEG compression, adding noise, filtering, etc. (4) The proposed method provides satisfactory generalization capability.
REVERSIBLE N-BIT TO N-BIT INTEGER HAAR-LIKE TRANSFORMS
Duchaineau, M; Joy, K I; Senecal, J
2004-02-14
We introduce TLHaar, an n-bit to n-bit reversible transform similar to the Haar IntegerWavelet Transform (IWT). TLHaar uses lookup tables that approximate the Haar IWT, but reorder the coefficients so they fit into n bits. TLHaar is suited for lossless compression in fixed-width channels, such as digital video channels and graphics hardware frame buffers.
Hey! A Brown Recluse Spider Bit Me!
... putting them on. Reviewed by: Elana Pearl Ben-Joseph, MD Date reviewed: April 2013 For Teens For Kids For Parents MORE ON THIS TOPIC Hey! A Fire Ant Stung Me! Hey! A Tarantula Bit Me! Hey! A Scorpion Stung Me! Hey! A Black Widow Spider Bit Me! Camping and Woods Safety ...
NASA Astrophysics Data System (ADS)
Fu, Hui-hua; Wang, Ping; Wang, Ran-ran; Liu, Xiao-xia; Guo, Li-xin; Yang, Yin-tang
2016-07-01
The average bit error rate ( ABER) performance of a decode-and-forward (DF) based relay-assisted free-space optical (FSO) communication system over gamma-gamma distribution channels considering the pointing errors is studied. With the help of Meijer's G-function, the probability density function (PDF) and cumulative distribution function (CDF) of the aggregated channel model are derived on the basis of the best path selection scheme. The analytical ABER expression is achieved and the system performance is then investigated with the influence of pointing errors, turbulence strengths and structure parameters. Monte Carlo (MC) simulation is also provided to confirm the analytical ABER expression.
Córcoles, A.D.; Magesan, Easwar; Srinivasan, Srikanth J.; Cross, Andrew W.; Steffen, M.; Gambetta, Jay M.; Chow, Jerry M.
2015-01-01
The ability to detect and deal with errors when manipulating quantum systems is a fundamental requirement for fault-tolerant quantum computing. Unlike classical bits that are subject to only digital bit-flip errors, quantum bits are susceptible to a much larger spectrum of errors, for which any complete quantum error-correcting code must account. Whilst classical bit-flip detection can be realized via a linear array of qubits, a general fault-tolerant quantum error-correcting code requires extending into a higher-dimensional lattice. Here we present a quantum error detection protocol on a two-by-two planar lattice of superconducting qubits. The protocol detects an arbitrary quantum error on an encoded two-qubit entangled state via quantum non-demolition parity measurements on another pair of error syndrome qubits. This result represents a building block towards larger lattices amenable to fault-tolerant quantum error correction architectures such as the surface code. PMID:25923200
Decoding of DBEC-TBED Reed-Solomon codes. [Double-Byte-Error-Correcting, Triple-Byte-Error-Detecting
NASA Technical Reports Server (NTRS)
Deng, Robert H.; Costello, Daniel J., Jr.
1987-01-01
A problem in designing semiconductor memories is to provide some measure of error control without requiring excessive coding overhead or decoding time. In LSI and VLSI technology, memories are often organized on a multiple bit (or byte) per chip basis. For example, some 256 K bit DRAM's are organized in 32 K x 8 bit-bytes. Byte-oriented codes such as Reed-Solomon (RS) codes can provide efficient low overhead error control for such memories. However, the standard iterative algorithm for decoding RS codes is too slow for these applications. The paper presents a special decoding technique for double-byte-error-correcting, triple-byte-error-detecting RS codes which is capable of high-speed operation. This technique is designed to find the error locations and the error values directly from the syndrome without having to use the iterative algorithm to find the error locator polynomial.
An Improved N-Bit to N-Bit Reversible Haar-Like Transform
Senecal, J G; Lindstrom, P; Duchaineau, M A; Joy, K I
2004-07-26
We introduce the Piecewise-Linear Haar (PLHaar) transform, a reversible n-bit to n-bit transform that is based on the Haar wavelet transform. PLHaar is continuous, while all current n-bit to n-bit methods are not, and is therefore uniquely usable with both lossy and lossless methods (e.g. image compression). PLHaar has both integer and continuous (i.e. non-discrete) forms. By keeping the coefficients to n bits PLHaar is particularly suited for use in hardware environments where channel width is limited, such as digital video channels and graphics hardware.
... and lens of your eye helps you focus. Refractive errors are vision problems that happen when the ... cornea, or aging of the lens. Four common refractive errors are Myopia, or nearsightedness - clear vision close ...
High performance 14-bit pipelined redundant signed digit ADC
NASA Astrophysics Data System (ADS)
Narula, Swina; Pandey, Sujata
2016-03-01
A novel architecture of a pipelined redundant-signed-digit analog to digital converter (RSD-ADC) is presented featuring a high signal to noise ratio (SNR), spurious free dynamic range (SFDR) and signal to noise plus distortion (SNDR) with efficient background correction logic. The proposed ADC architecture shows high accuracy with a high speed circuit and efficient utilization of the hardware. This paper demonstrates the functionality of the digital correction logic of 14-bit pipelined ADC at each 1.5 bit/stage. This prototype of ADC architecture accounts for capacitor mismatch, comparator offset and finite Op-Amp gain error in the MDAC (residue amplification circuit) stages. With the proposed architecture of ADC, SNDR obtained is 85.89 dB, SNR is 85.9 dB and SFDR obtained is 102.8 dB at the sample rate of 100 MHz. This novel architecture of digital correction logic is transparent to the overall system, which is demonstrated by using 14-bit pipelined ADC. After a latency of 14 clocks, digital output will be available at every clock pulse. To describe the circuit behavior of the ADC, VHDL and MATLAB programs are used. The proposed architecture is also capable of reducing the digital hardware. Silicon area is also the complexity of the design.
Noyes, H.P.
1990-01-29
We construct discrete space-time coordinates separated by the Lorentz-invariant intervals h/mc in space and h/mc{sup 2} in time using discrimination (XOR) between pairs of independently generated bit-strings; we prove that if this space is homogeneous and isotropic, it can have only 1, 2 or 3 spacial dimensions once we have related time to a global ordering operator. On this space we construct exact combinatorial expressions for free particle wave functions taking proper account of the interference between indistinguishable alternative paths created by the construction. Because the end-points of the paths are fixed, they specify completed processes; our wave functions are born collapsed''. A convenient way to represent this model is in terms of complex amplitudes whose squares give the probability for a particular set of observable processes to be completed. For distances much greater than h/mc and times much greater than h/mc{sup 2} our wave functions can be approximated by solutions of the free particle Dirac and Klein-Gordon equations. Using a eight-counter paradigm we relate this construction to scattering experiments involving four distinguishable particles, and indicate how this can be used to calculate electromagnetic and weak scattering processes. We derive a non-perturbative formula relating relativistic bound and resonant state energies to mass ratios and coupling constants, equivalent to our earlier derivation of the Bohr relativistic formula for hydrogen. Using the Fermi-Yang model of the pion as a relativistic bound state containing a nucleon-antinucleon pair, we find that (G{sub {pi}N}{sup 2}){sup 2} = (2m{sub N}/m{sub {pi}}){sup 2} {minus} 1. 21 refs., 1 fig.
Changes realized from extended bit-depth and metal artifact reduction in CT
Glide-Hurst, C.; Chen, D.; Zhong, H.; Chetty, I. J.
2013-06-15
Purpose: High-Z material in computed tomography (CT) yields metal artifacts that degrade image quality and may cause substantial errors in dose calculation. This study couples a metal artifact reduction (MAR) algorithm with enhanced 16-bit depth (vs standard 12-bit) to quantify potential gains in image quality and dosimetry. Methods: Extended CT to electron density (CT-ED) curves were derived from a tissue characterization phantom with titanium and stainless steel inserts scanned at 90-140 kVp for 12- and 16-bit reconstructions. MAR was applied to sinogram data (Brilliance BigBore CT scanner, Philips Healthcare, v.3.5). Monte Carlo simulation (MC-SIM) was performed on a simulated double hip prostheses case (Cerrobend rods embedded in a pelvic phantom) using BEAMnrc/Dosxyz (400 000 0000 histories, 6X, 10 Multiplication-Sign 10 cm{sup 2} beam traversing Cerrobend rod). A phantom study was also conducted using a stainless steel rod embedded in solid water, and dosimetric verification was performed with Gafchromic film analysis (absolute difference and gamma analysis, 2% dose and 2 mm distance to agreement) for plans calculated with Anisotropic Analytic Algorithm (AAA, Eclipse v11.0) to elucidate changes between 12- and 16-bit data. Three patients (bony metastases to the femur and humerus, and a prostate cancer case) with metal implants were reconstructed using both bit depths, with dose calculated using AAA and derived CT-ED curves. Planar dose distributions were assessed via matrix analyses and using gamma criteria of 2%/2 mm. Results: For 12-bit images, CT numbers for titanium and stainless steel saturated at 3071 Hounsfield units (HU), whereas for 16-bit depth, mean CT numbers were much larger (e.g., titanium and stainless steel yielded HU of 8066.5 {+-} 56.6 and 13 588.5 {+-} 198.8 for 16-bit uncorrected scans at 120 kVp, respectively). MC-SIM was well-matched between 12- and 16-bit images except downstream of the Cerrobend rod, where 16-bit dose was {approx}6
Cheat sensitive quantum bit commitment via pre- and post-selected quantum states
NASA Astrophysics Data System (ADS)
Li, Yan-Bing; Wen, Qiao-Yan; Li, Zi-Chen; Qin, Su-Juan; Yang, Ya-Tao
2014-01-01
Cheat sensitive quantum bit commitment is a most important and realizable quantum bit commitment (QBC) protocol. By taking advantage of quantum mechanism, it can achieve higher security than classical bit commitment. In this paper, we propose a QBC schemes based on pre- and post-selected quantum states. The analysis indicates that both of the two participants' cheat strategies will be detected with non-zero probability. And the protocol can be implemented with today's technology as a long-term quantum memory is not needed.
Room temperature single-photon detectors for high bit rate quantum key distribution
Comandar, L. C.; Patel, K. A.; Fröhlich, B. Lucamarini, M.; Sharpe, A. W.; Dynes, J. F.; Yuan, Z. L.; Shields, A. J.; Penty, R. V.
2014-01-13
We report room temperature operation of telecom wavelength single-photon detectors for high bit rate quantum key distribution (QKD). Room temperature operation is achieved using InGaAs avalanche photodiodes integrated with electronics based on the self-differencing technique that increases avalanche discrimination sensitivity. Despite using room temperature detectors, we demonstrate QKD with record secure bit rates over a range of fiber lengths (e.g., 1.26 Mbit/s over 50 km). Furthermore, our results indicate that operating the detectors at room temperature increases the secure bit rate for short distances.
Finger Vein Recognition Based on a Personalized Best Bit Map
Yang, Gongping; Xi, Xiaoming; Yin, Yilong
2012-01-01
Finger vein patterns have recently been recognized as an effective biometric identifier. In this paper, we propose a finger vein recognition method based on a personalized best bit map (PBBM). Our method is rooted in a local binary pattern based method and then inclined to use the best bits only for matching. We first present the concept of PBBM and the generating algorithm. Then we propose the finger vein recognition framework, which consists of preprocessing, feature extraction, and matching. Finally, we design extensive experiments to evaluate the effectiveness of our proposal. Experimental results show that PBBM achieves not only better performance, but also high robustness and reliability. In addition, PBBM can be used as a general framework for binary pattern based recognition. PMID:22438735
The 40 Gbps cascaded bit-interleaving PON
NASA Astrophysics Data System (ADS)
Vyncke, A.; Torfs, G.; Van Praet, C.; Verbeke, M.; Duque, A.; Suvakovic, D.; Chow, H. K.; Yin, X.
2015-12-01
In this paper, a 40 Gbps cascaded bit-interleaving passive optical network (CBI-PON) is proposed to achieve power reduction in the network. The massive number of devices in the access network makes that power consumption reduction in this part of the network has a major impact on the total network power consumption. Starting from the proven BiPON technology, an extension to this concept is proposed to introduce multiple levels of bit-interleaving. The paper discusses the CBI protocol in detail, as well as an ASIC implementation of the required custom CBI Repeater and End-ONT. From the measurements of this first 40 Gbps ASIC prototype, power consumption reduction estimates are presented.
Effect of video decoder errors on video interpretability
NASA Astrophysics Data System (ADS)
Young, Darrell L.
2014-06-01
The advancement in video compression technology can result in more sensitivity to bit errors. Bit errors can propagate causing sustained loss of interpretability. In the worst case, the decoder "freezes" until it can re-synchronize with the stream. Detection of artifacts enables downstream processes to avoid corrupted frames. A simple template approach to detect block stripes and a more advanced cascade approach to detect compression artifacts was shown to correlate to the presence of artifacts and decoder messages.
Spin glasses and error-correcting codes
NASA Technical Reports Server (NTRS)
Belongie, M. L.
1994-01-01
In this article, we study a model for error-correcting codes that comes from spin glass theory and leads to both new codes and a new decoding technique. Using the theory of spin glasses, it has been proven that a simple construction yields a family of binary codes whose performance asymptotically approaches the Shannon bound for the Gaussian channel. The limit is approached as the number of information bits per codeword approaches infinity while the rate of the code approaches zero. Thus, the codes rapidly become impractical. We present simulation results that show the performance of a few manageable examples of these codes. In the correspondence that exists between spin glasses and error-correcting codes, the concept of a thermal average leads to a method of decoding that differs from the standard method of finding the most likely information sequence for a given received codeword. Whereas the standard method corresponds to calculating the thermal average at temperature zero, calculating the thermal average at a certain optimum temperature results instead in the sequence of most likely information bits. Since linear block codes and convolutional codes can be viewed as examples of spin glasses, this new decoding method can be used to decode these codes in a way that minimizes the bit error rate instead of the codeword error rate. We present simulation results that show a small improvement in bit error rate by using the thermal average technique.
A 1 GHz sample rate, 256-channel, 1-bit quantization, CMOS, digital correlator chip
NASA Technical Reports Server (NTRS)
Timoc, C.; Tran, T.; Wongso, J.
1992-01-01
This paper describes the development of a digital correlator chip with the following features: 1 Giga-sample/second; 256 channels; 1-bit quantization; 32-bit counters providing up to 4 seconds integration time at 1 GHz; and very low power dissipation per channel. The improvements in the performance-to-cost ratio of the digital correlator chip are achieved with a combination of systolic architecture, novel pipelined differential logic circuits, and standard 1.0 micron CMOS process.
PDC bits find applications in Oklahoma drilling
Offenbacher, L.A.; McDermaid, J.D.; Patterson, C.R.
1983-02-01
Drilling in Oklahoma is difficult by any standards. Polycrystalline diamond cutter (PDC) bits, with proven success drilling soft, homogenous formations common in the North Sea and U.S. Gulf Coast regions, have found some significant ''spot'' applications in Oklahoma. Applications qualified by bit design and application development over the past two (2) years include slim hole drilling in the deep Anadarko Basin, deviation control in Southern Oklahoma, drilling on mud motors, drilling in oil base mud, drilling cement, sidetracking, coring and some rotary drilling in larger hole sizes. PDC bits are formation sensitive, and care must be taken in selecting where to run them in Oklahoma. Most of the successful runs have been in water base mud drilling hard shales and soft, unconsolidated sands and lime, although bit life is often extended in oil-base muds.
FastBit: Interactively Searching Massive Data
Wu, Kesheng; Ahern, Sean; Bethel, E. Wes; Chen, Jacqueline; Childs, Hank; Cormier-Michel, Estelle; Geddes, Cameron; Gu, Junmin; Hagen, Hans; Hamann, Bernd; Koegler, Wendy; Lauret, Jerome; Meredith, Jeremy; Messmer, Peter; Otoo, Ekow; Perevoztchikov, Victor; Poskanzer, Arthur; Prabhat,; Rubel, Oliver; Shoshani, Arie; Sim, Alexander; Stockinger, Kurt; Weber, Gunther; Zhang, Wei-Ming
2009-06-23
As scientific instruments and computer simulations produce more and more data, the task of locating the essential information to gain insight becomes increasingly difficult. FastBit is an efficient software tool to address this challenge. In this article, we present a summary of the key underlying technologies, namely bitmap compression, encoding, and binning. Together these techniques enable FastBit to answer structured (SQL) queries orders of magnitude faster than popular database systems. To illustrate how FastBit is used in applications, we present three examples involving a high-energy physics experiment, a combustion simulation, and an accelerator simulation. In each case, FastBit significantly reduces the response time and enables interactive exploration on terabytes of data.
A practical quantum bit commitment protocol
NASA Astrophysics Data System (ADS)
Arash Sheikholeslam, S.; Aaron Gulliver, T.
2012-01-01
In this paper, we introduce a new quantum bit commitment protocol which is secure against entanglement attacks. A general cheating strategy is examined and shown to be practically ineffective against the proposed approach.
28-Bit serial word simulator/monitor
NASA Technical Reports Server (NTRS)
Durbin, J. W.
1979-01-01
Modular interface unit transfers data at high speeds along four channels. Device expedites variable-word-length communication between computers. Operation eases exchange of bit information by automatically reformatting coded input data and status information to match requirements of output.
Diffusion bonding of Stratapax for drill bits
Middleton, J.N.; Finger, J.T.
1983-01-01
A process has been developed for the diffusion bonding of General Electric's Stratapax drill blanks to support studs for cutter assemblies in drill bits. The diffusion bonding process is described and bond strength test data are provided for a variety of materials. The extensive process details, provided in the Appendices, should be sufficient to enable others to successfully build diffusion-bonded drill bit cutter assemblies.
NASA Astrophysics Data System (ADS)
Dey, Sukomal; Koul, Shiban K.
2015-06-01
This paper presents a frequency tunable 5-bit true-time-delay digital phase shifter using radio frequency microelectromechanical system (RF MEMS) technology. The phase shifter is based on the distributed MEMS transmission line (DMTL) concept utilizing a MEMS varactor. The main source of frequency tuning in this work is a bridge actuation mechanism followed by capacitance variation. Two stages of actuation mechanisms (push and pull) are used to achieve a 2:1 tuning ratio. Accurate control of the actuation voltage between the pull to push stages contributes differential phase shift over the band of interest. The functional behavior of the push-pull actuation over the phase shifter application is theoretically established, experimentally investigated and validated with simulation. The phase shifter is fabricated monolithically using a gold based surface micromachining process on an alumina substrate. The individual primary phase-bits (11.25°/22.5°/45°/90°/180°) that are the fundamental building blocks of the complete 5-bit phase shifter are designed, fabricated and experimentally characterized from 10-25 GHz for specific applications. Finally, the complete 5-bit phase shifter demonstrates an average phase error of 4.32°, 2.8°, 1° and 1.58°, an average insertion loss of 3.76, 4.1, 4.2 and 4.84 dB and an average return loss of 11.7, 12, 14 and 11.8 dB at 10, 12, 17.2 and 25 GHz, respectively. To the best of the authors’ knowledge, this is the first reported band tunable stand alone 5-bit phase shifter in the literature which can work over the large spectrum for different applications. The total area of the 5-bit phase shifter is 15.6 mm2. Furthermore, the cold-switched reliability of the unit cell and the complete 5-bit MEMS phase shifter are extensively investigated and presented.
Just noticeable disparity error-based depth coding for three-dimensional video
NASA Astrophysics Data System (ADS)
Luo, Lei; Tian, Xiang; Chen, Yaowu
2014-07-01
A just noticeable disparity error (JNDE) measurement to describe the maximum tolerated error of depth maps is proposed. Any error of depth value inside the JNDE range would not cause a noticeable distortion observed by human eyes. The JNDE values are used to preprocess the original depth map in the prediction process during the depth coding and to adjust the prediction residues for further improvement of the coding quality. The proposed scheme can be incorporated in any standardized video coding algorithm based on prediction and transform. The experimental results show that the proposed method can achieve a 34% bit rate saving for depth video coding. Moreover, the perceptual quality of the synthesized view is also improved by the proposed method.
A forward error correction technique using a high-speed, high-rate single chip codec
NASA Technical Reports Server (NTRS)
Boyd, R. W.; Hartman, W. F.; Jones, Robert E.
1989-01-01
The authors describe an error-correction coding approach that allows operation in either burst or continuous modes at data rates of multiple hundreds of megabits per second. Bandspreading is low since the code rate is 7/8 or greater, which is consistent with high-rate link operation. The encoder, along with a hard-decision decoder, fits on a single application-specific integrated circuit (ASIC) chip. Soft-decision decoding is possible utilizing applique hardware in conjunction with the hard-decision decoder. Expected coding gain is a function of the application and is approximately 2.5 dB for hard-decision decoding at 10-5 bit-error rate with phase-shift-keying modulation and additive Gaussian white noise interference. The principal use envisioned for this technique is to achieve a modest amount of coding gain on high-data-rate, bandwidth-constrained channels. Data rates of up to 300 Mb/s can be accommodated by the codec chip. The major objective is burst-mode communications, where code words are composed of 32 n data bits followed by 32 overhead bits.
Error correction for free-space optical interconnects: space-time resource optimization.
Neifeld, M A; Kostuk, R K
1998-01-10
We study the joint optimization of time and space resources withinfree-space optical interconnect (FSOI) systems. Both analyticaland simulation results are presented to support this optimization studyfor two different models of FSOI cross-talk noise: diffraction froma rectangular aperture and Gaussian propagation. Under realisticpower and signal-to-noise ratio constraints, optimum designs based onthe Gaussian propagation model achieve a capacity of 2.91 x10(15) bits s(-1) m(-2), while therectangular model offers a smaller capacity of 1.91 x10(13) bits s(-1) m(-2). We alsostudy the use of error-correction codes (ECC) within FSOIsystems. We present optimal Reed-Solomon codes of various length, and their use is shown to facilitate an increase in both spatialdensity and data rate, resulting in FSOI capacity gains in excess of8.2 for the rectangular model and 3.7 for the Gaussian case. Atolerancing study of FSOI systems shows that ECC can provide toleranceto implementational error sources. We find that optimally codedFSOI systems can fail when system errors become large, and we present acompromise solution that results in a balanced design in time, space, and error-correction resources. PMID:18268585
1998-09-01
Global access to HIV/AIDS treatment was the universal theme at the 12th World AIDS Conference. However, 90 percent of people with AIDS do not have access to available therapy. Special attention is needed in dealing with HIV infected persons who are incarcerated and do not have access to the same level of care as the rest of the population. Although perinatal AIDS is now regarded as a preventable disease in the United States, many pregnant women also do not have access to prevention or treatment information. In many parts of the world, women do not have the ability to negotiate safer sexual practices and therefore, remain vulnerable to HIV infection. Partnerships are needed between the fields of prevention, treatment, biomedical research, and behavioral science in order to possibly achieve global access to treatment. PMID:11367485
Nugget hardfacing toughens roller cone bits
1996-11-25
A new hardfacing material made of pure sintered tungsten carbide nuggets has improved roller cone rock bit performance in extremely hard lithologies, increasing penetration rates and extending bit life through multiple formations. In a recent test run in the Shushufindi 95 wells in Ecuador, a Security DBS 9 7/8-in. MPSF IADC 117M (International Association of Drilling Contractors bit code) bit with this new hardfacing drilled out the float equipment, cement, and show and then 3,309 ft of hard formations. The bit drilled through the Orteguaza claystone/shale/sand and chert formations and then to total depth at 6,309 ft in the Tiyuyacu shale/sand. The 3,309-ft interval was drilled at an average penetration rate (ROP) of 52.5 ft/hr. The proprietary nugget material was tested according to the American Society for Testing Materials (ASTM) G65 wear test method, a standard industry method of measuring wear resistance. The nugget material had ASTM wear test resistance more than twice that of standard hardfacing from conventional tungsten carbide.
Using magnetic permeability bits to store information
NASA Astrophysics Data System (ADS)
Timmerwilke, John; Petrie, J. R.; Wieland, K. A.; Mencia, Raymond; Liou, Sy-Hwang; Cress, C. D.; Newburgh, G. A.; Edelstein, A. S.
2015-10-01
Steps are described in the development of a new magnetic memory technology, based on states with different magnetic permeability, with the capability to reliably store large amounts of information in a high-density form for decades. The advantages of using the permeability to store information include an insensitivity to accidental exposure to magnetic fields or temperature changes, both of which are known to corrupt memory approaches that rely on remanent magnetization. The high permeability media investigated consists of either films of Metglas 2826 MB (Fe40Ni38Mo4B18) or bilayers of permalloy (Ni78Fe22)/Cu. Regions of films of the high permeability media were converted thermally to low permeability regions by laser or ohmic heating. The permeability of the bits was read by detecting changes of an external 32 Oe probe field using a magnetic tunnel junction 10 μm away from the media. Metglas bits were written with 100 μs laser pulses and arrays of 300 nm diameter bits were read. The high and low permeability bits written using bilayers of permalloy/Cu are not affected by 10 Mrad(Si) of gamma radiation from a 60Co source. An economical route for writing and reading bits as small at 20 nm using a variation of heat assisted magnetic recording is discussed.
A Ku band 5 bit MEMS phase shifter for active electronically steerable phased array applications
NASA Astrophysics Data System (ADS)
Sharma, Anesh K.; Gautam, Ashu K.; Farinelli, Paola; Dutta, Asudeb; Singh, S. G.
2015-03-01
The design, fabrication and measurement of a 5 bit Ku band MEMS phase shifter in different configurations, i.e. a coplanar waveguide and microstrip, are presented in this work. The development architecture is based on the hybrid approach of switched and loaded line topologies. All the switches are monolithically manufactured on a 200 µm high resistivity silicon substrate using 4 inch diameter wafers. The first three bits (180°, 90° and 45°) are realized using switched microstrip lines and series ohmic MEMS switches whereas the fourth and fifth bits (22.5° and 11.25°) consist of microstrip line sections loaded by shunt ohmic MEMS devices. Individual bits are fabricated and evaluated for performance and the monolithic device is a 5 bit Ku band (16-18 GHz) phase shifter with very low average insertion loss of the order of 3.3 dB and a return loss better than 15 dB over the 32 states with a chip area of 44 mm2. A total phase shift of 348.75° with phase accuracy within 3° is achieved over all of the states. The performance of individual bits has been optimized in order to achieve an integrated performance so that they can be implemented into active electronically steerable antennas for phased array applications.
Quantum key distribution using qudits that each encode one bit of raw key
NASA Astrophysics Data System (ADS)
Chau, H. F.
2015-12-01
All known qudit-based prepare-and-measure quantum key distribution (PMQKD) schemes are more error resilient than their qubit-based counterparts. Their high error resiliency comes partly from the careful encoding of multiple bits of signals used to generate the raw key in each transmitted qudit so that the same eavesdropping attempt causes a higher bit error rate (BER) in the raw key. Here I show that highly-error-tolerant PMQKD schemes can be constructed simply by encoding one bit of classical information in each transmitted qudit in the form (|i > ±|j >) /√{2 } , where |i > 's form an orthonormal basis of the 2n-dimensional Hilbert space. Moreover, I prove that these schemes can tolerate up to the theoretical maximum of a 50% BER for n ≥2 provided the raw key is generated under a certain technical condition, making them extremely-error-tolerant PMQKD schemes involving the transmission of unentangled finite-dimensional qudits. This shows the potential of processing quantum information using lower-dimensional quantum signals encoded in a higher-dimensional quantum state.
Bit Storage by 360 (°) Domain Walls in Ferromagnetic Nanorings
NASA Astrophysics Data System (ADS)
Muratov, Cyrill B.; Osipov, Viatcheslav V.
2009-08-01
We propose a design for the magnetic memory cell which allows an efficient storage, recording, and readout of information on the basis of thin film ferromagnetic nanorings. The information bit is represented by the polarity of a stable 360$^\\circ$ domain wall introduced into the ring. Switching between the two magnetization states is achieved by the current applied to a wire passing through the ring, whereby the $360^\\circ$ domain wall splits into two charged $180^\\circ$ walls, which then move to the opposite extreme of the ring to recombine into a $360^\\circ$ wall of the opposite polarity.
Managing the number of tag bits transmitted in a bit-tracking RFID collision resolution protocol.
Landaluce, Hugo; Perallos, Asier; Angulo, Ignacio
2014-01-01
Radio Frequency Identification (RFID) technology faces the problem of message collisions. The coexistence of tags sharing the communication channel degrades bandwidth, and increases the number of bits transmitted. The window methodology, which controls the number of bits transmitted by the tags, is applied to the collision tree (CT) protocol to solve the tag collision problem. The combination of this methodology with the bit-tracking technology, used in CT, improves the performance of the window and produces a new protocol which decreases the number of bits transmitted. The aim of this paper is to show how the CT bit-tracking protocol is influenced by the proposed window, and how the performance of the novel protocol improves under different conditions of the scenario. Therefore, we have performed a fair comparison of the CT protocol, which uses bit-tracking to identify the first collided bit, and the new proposed protocol with the window methodology. Simulations results show that the proposed window positively decreases the total number of bits that are transmitted by the tags, and outperforms the CT protocol latency in slow tag data rate scenarios. PMID:24406861
Managing the Number of Tag Bits Transmitted in a Bit-Tracking RFID Collision Resolution Protocol
Landaluce, Hugo; Perallos, Asier; Angulo, Ignacio
2014-01-01
Radio Frequency Identification (RFID) technology faces the problem of message collisions. The coexistence of tags sharing the communication channel degrades bandwidth, and increases the number of bits transmitted. The window methodology, which controls the number of bits transmitted by the tags, is applied to the collision tree (CT) protocol to solve the tag collision problem. The combination of this methodology with the bit-tracking technology, used in CT, improves the performance of the window and produces a new protocol which decreases the number of bits transmitted. The aim of this paper is to show how the CT bit-tracking protocol is influenced by the proposed window, and how the performance of the novel protocol improves under different conditions of the scenario. Therefore, we have performed a fair comparison of the CT protocol, which uses bit-tracking to identify the first collided bit, and the new proposed protocol with the window methodology. Simulations results show that the proposed window positively decreases the total number of bits that are transmitted by the tags, and outperforms the CT protocol latency in slow tag data rate scenarios. PMID:24406861
Evaluations of bit sleeve and twisted-body bit designs for controlling roof bolter dust
Beck, T.W.
2015-01-01
Drilling into coal mine roof strata to install roof bolts has the potential to release substantial quantities of respirable dust. Due to the proximity of drill holes to the breathing zone of roof bolting personnel, dust escaping the holes and avoiding capture by the dust collection system pose a potential respiratory health risk. Controls are available to complement the typical dry vacuum collection system and minimize harmful exposures during the initial phase of drilling. This paper examines the use of a bit sleeve in combination with a dust-hog-type bit to improve dust extraction during the critical initial phase of drilling. A twisted-body drill bit is also evaluated to determine the quantity of dust liberated in comparison with the dust-hog-type bit. Based on the results of our laboratory tests, the bit sleeve may reduce dust emissions by one-half during the initial phase of drilling before the drill bit is fully enclosed by the drill hole. Because collaring is responsible for the largest dust liberations, overall dust emission can also be substantially reduced. The use of a twisted-body bit has minimal improvement on dust capture compared with the commonly used dust-hog-type bit. PMID:26257435
Designing an efficient LT-code with unequal error protection for image transmission
NASA Astrophysics Data System (ADS)
S. Marques, F.; Schwartz, C.; Pinho, M. S.; Finamore, W. A.
2015-10-01
The use of images from earth observation satellites is spread over different applications, such as a car navigation systems and a disaster monitoring. In general, those images are captured by on board imaging devices and must be transmitted to the Earth using a communication system. Even though a high resolution image can produce a better Quality of Service, it leads to transmitters with high bit rate which require a large bandwidth and expend a large amount of energy. Therefore, it is very important to design efficient communication systems. From communication theory, it is well known that a source encoder is crucial in an efficient system. In a remote sensing satellite image transmission, this efficiency is achieved by using an image compressor, to reduce the amount of data which must be transmitted. The Consultative Committee for Space Data Systems (CCSDS), a multinational forum for the development of communications and data system standards for space flight, establishes a recommended standard for a data compression algorithm for images from space systems. Unfortunately, in the satellite communication channel, the transmitted signal is corrupted by the presence of noise, interference signals, etc. Therefore, the receiver of a digital communication system may fail to recover the transmitted bit. Actually, a channel code can be used to reduce the effect of this failure. In 2002, the Luby Transform code (LT-code) was introduced and it was shown that it was very efficient when the binary erasure channel model was used. Since the effect of the bit recovery failure depends on the position of the bit in the compressed image stream, in the last decade many e orts have been made to develop LT-code with unequal error protection. In 2012, Arslan et al. showed improvements when LT-codes with unequal error protection were used in images compressed by SPIHT algorithm. The techniques presented by Arslan et al. can be adapted to work with the algorithm for image compression
Audio and video bit-rate reduction
NASA Astrophysics Data System (ADS)
Haskell, B. G.; Steele, R.
1981-02-01
The problem of estimating limits of bit-rate reduction for audio and video information is addressed. It is noted that binary encoding of such signals is performed by a variety of techniques, which are classified here into two categories (waveform and parameter). Encoders are compared on the basis of bits per Nyquist sample. Since minimizing the Nyquist sample requires a use of source signal statistics and human perception, audio and video sources and their statistics are discussed, as are the salient properties of hearing and vision and subjective assessments of quality. The present state of waveform and parameter encoding is assessed. It is predicted that waveform encoders will be refined to the point where bit rates will be nearly optimum but also highly variable. It is concluded that dramatic reductions will come about only through sophisticated parameter encoding.
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Friction of drill bits under Martian pressure
NASA Astrophysics Data System (ADS)
Zacny, K. A.; Cooper, G. A.
2007-03-01
Frictional behavior was investigated for two materials that are good candidates for Mars drill bits: Diamond Impregnated Segments and Polycrystalline Diamond Compacts (PDC). The bits were sliding against dry sandstone and basalt rocks under both Earth and Mars atmospheric pressures and also at temperatures ranging from subzero to over 400 °C. It was found that the friction coefficient dropped from approximately 0.16 to 0.1 as the pressure was lowered from the Earth's pressure to Mars' pressure, at room temperature. This is thought to be a result of the loss of weakly bound water on the sliding surfaces. Holding the pressure at 5 torr and increasing the temperature to approximately 200°C caused a sudden increase in the friction coefficient by approximately 50%. This is attributed to the loss of surface oxides. If no indication of the bit temperature is available, an increase in drilling torque could be misinterpreted as being caused by an increase in auger torque (due to accumulation of cuttings) rather than being the result of a loss of oxide layers due to elevated bit temperatures. An increase in rotational speed (to allow for clearing of cuttings) would then cause greater frictional heating and would increase the drilling torque further. Therefore it would be advisable to monitor the bit temperature or, if that is not possible, to include pauses in drilling to allow the heat to dissipate. Higher friction would also accelerate the wear of the drill bit and in turn reduce the depth of the hole.
A simple model of bit whirl for deep drilling applications
NASA Astrophysics Data System (ADS)
Kovalyshen, Yevhen
2013-11-01
A simple analytical model of bit whirl is presented. In contrast to the previous works, which consider bottom hole assembly mass imbalance to model bit whirl, the model here takes into account the history-dependent boundary conditions at the bit-rock interface as well as the bit geometry. In particular, an analytical expression for the bit-rock interaction is derived. It is shown that the bit geometry affects the bit-rock interaction only through three dimensionless parameters. Depending on the value of these parameters the system can be stable or undergo forward or backward whirl.
Model for the bit-rock interaction analysis
NASA Astrophysics Data System (ADS)
Palmov, Vladimir A.; Vetyukov, Yury M.
2002-02-01
In this report a model for drilling response of the so- called drag bits (or PDC bits) is presented. Forces acting on a single cutter are supposed to be known. Discrete and continuous cutters distribution over the bit surface are considered. Both lead to similar relations between the bit kinematics characteristics and the force factors acting on it. While the bit penetration rate into the rock is small, the force and the torque are shown to depend linearly on the ratio between the bit transitional and rotational velocities (the depth of cut per revolution). Particular cases of the bit shape are compared.
Anti-incendive coal cutter bits
Cheng, L.; Liebman, I.
1981-11-09
The invention is an improved cutter bit, useable with a material cutting mining machine, wherein the bit has an elongated shank portion which retains a cutting tip portion. The tip portion is enlarged in cross-section at its junction with the shank to partially mask the adjacent interface shank surface and thereby protect the shank from exposure at the point of impact. Two basic designs embody the invention. One is a mushroom shaped tip and the other is a dovetail tip/shank design.
Shaft drill bit with overlapping cutter arrangement
Cunningham, R.A.; Pessier, R.C.
1981-02-03
An earth boring drill bit for large diameter shafts has an improved cutter arrangement. The drill bit has a cutter support member with a number of cutters mounted to it for disintegrating the earth formation face. At least one inner cutter is mounted near the center for cutting the center area. A number of gage cutters are mounted at the periphery to cut the gage area of the shaft. A number of intermediate cutters are spaced between the inner and gage cutters. Each intermediate cutter overlaps onehalf of its width with an adjacent intermediate cutter.
Quantum bit commitment under Gaussian constraints
NASA Astrophysics Data System (ADS)
Mandilara, Aikaterini; Cerf, Nicolas J.
2012-06-01
Quantum bit commitment has long been known to be impossible. Nevertheless, just as in the classical case, imposing certain constraints on the power of the parties may enable the construction of asymptotically secure protocols. Here, we introduce a quantum bit commitment protocol and prove that it is asymptotically secure if cheating is restricted to Gaussian operations. This protocol exploits continuous-variable quantum optical carriers, for which such a Gaussian constraint is experimentally relevant as the high optical nonlinearity needed to effect deterministic non-Gaussian cheating is inaccessible.
Progressive and Error-Resilient Transmission Strategies for VLC Encoded Signals over Noisy Channels
NASA Astrophysics Data System (ADS)
Jégou, Hervé; Guillemot, Christine
2006-12-01
This paper addresses the issue of robust and progressive transmission of signals (e.g., images, video) encoded with variable length codes (VLCs) over error-prone channels. This paper first describes bitstream construction methods offering good properties in terms of error resilience and progressivity. In contrast with related algorithms described in the literature, all proposed methods have a linear complexity as the sequence length increases. The applicability of soft-input soft-output (SISO) and turbo decoding principles to resulting bitstream structures is investigated. In addition to error resilience, the amenability of the bitstream construction methods to progressive decoding is considered. The problem of code design for achieving good performance in terms of error resilience and progressive decoding with these transmission strategies is then addressed. The VLC code has to be such that the symbol energy is mainly concentrated on the first bits of the symbol representation (i.e., on the first transitions of the corresponding codetree). Simulation results reveal high performance in terms of symbol error rate (SER) and mean-square reconstruction error (MSE). These error-resilience and progressivity properties are obtained without any penalty in compression efficiency. Codes with such properties are of strong interest for the binarization of[InlineEquation not available: see fulltext.]-ary sources in state-of-the-art image, and video coding systems making use of, for example, the EBCOT or CABAC algorithms. A prior statistical analysis of the signal allows the construction of the appropriate binarization code.
A 16K-bit static IIL RAM with 25-ns access time
NASA Astrophysics Data System (ADS)
Inabe, Y.; Hayashi, T.; Kawarada, K.; Miwa, H.; Ogiue, K.
1982-04-01
A 16,384 x 1-bit RAM with 25-ns access time, 600-mW power dissipation, and 33 sq mm chip size has been developed. Excellent speed-power performance with high packing density has been achieved by an oxide isolation technology in conjunction with novel ECL circuit techniques and IIL flip-flop memory cells, 980 sq microns (35 x 28 microns) in cell size. Development results have shown that IIL flip-flop memory cell is a trump card for assuring achievement of a high-performance large-capacity bipolar RAM, in the above 16K-bit/chip area.
Protected Polycrystalline Diamond Compact Bits For Hard Rock Drilling
Robert Lee Cardenas
2000-10-31
Two bits were designed. One bit was fabricated and tested at Terra-Tek's Drilling Research Laboratory. Fabrication of the second bit was not completed due to complications in fabrication and meeting scheduled test dates at the test facility. A conical bit was tested in a Carthage Marble (compressive strength 14,500 psi) and Sierra White Granite (compressive strength 28,200 psi). During the testing, Hydraulic Horsepower, Bit Weight, Rotation Rate, were varied for the Conical Bit, a Varel Tricone Bit and Varel PDC bit. The Conical Bi did cut rock at a reasonable rate in both rocks. Beneficial effects from the near and through cutter water nozzles were not evident in the marble due to test conditions and were not conclusive in the granite due to test conditions. At atmospheric drilling, the Conical Bit's penetration rate was as good as the standard PDC bit and better than the Tricone Bit. Torque requirements for the Conical Bit were higher than that required for the Standard Bits. Spudding the conical bit into the rock required some care to avoid overloading the nose cutters. The nose design should be evaluated to improve the bit's spudding characteristics.
Power of one bit of quantum information in quantum metrology
NASA Astrophysics Data System (ADS)
Cable, Hugo; Gu, Mile; Modi, Kavan
2016-04-01
We present a model of quantum metrology inspired by the computational model known as deterministic quantum computation with one quantum bit (DQC1). Using only one pure qubit together with l fully mixed qubits we obtain measurement precision (defined as root-mean-square error for the parameter being estimated) at the standard quantum limit, which is typically obtained using the same number of uncorrelated qubits in fully pure states. In principle, the standard quantum limit can be exceeded using an additional qubit which adds only a small amount of purity. We show that the discord in the final state vanishes only in the limit of attaining infinite precision for the parameter being estimated.
Jet bit with onboard deviation means
Cherrington, M.D.
1990-02-13
This patent describes a directional drill bit utilizing pressurized fluid as a means for eroding earth in a forward path of said bit. It comprises: an elongate hollow body having a first proximal end and a first distal end, and having at least a rigid first section and at least a rigid second section. The first section and said second section being connected one to the other by a flexible joint positioned intermediately of said first section and said second section, with the combination of said first section, said flexible joint and said second section providing a conduit having lead-free annular sidewalls. The said combination thereby defining said elongate hollow body; a connecting means formed by said first proximal end for joining said elongated hollow body with an appropriate fluid conveyance means used to transport said pressurized fluid; a nozzle means borne by said first distal end. The nozzle means comprising a nozzle plate having at least one jet nozzle attached to and carried by said nozzle plate; and an articulation means. The articulation means being responsive to changes in fluid pressure and permitting a forward portion of said bit bearing said nozzle structure to change angular position with respect to an aft portion of the bit.
1 /N perturbations in superstring bit models
NASA Astrophysics Data System (ADS)
Thorn, Charles B.
2016-03-01
We develop the 1 /N expansion for stable string bit models, focusing on a model with bit creation operators carrying only transverse spinor indices a =1 ,…,s . At leading order (N =∞ ), this model produces a (discretized) light cone string with a "transverse space" of s Grassmann worldsheet fields. Higher orders in the 1 /N expansion are shown to be determined by the overlap of a single large closed chain (discretized string) with two smaller closed chains. In the models studied here, the overlap is not accompanied with operator insertions at the break/join point. Then, the requirement that the discretized overlap has a smooth continuum limit leads to the critical Grassmann "dimension" of s =24 . This "protostring," a Grassmann analog of the bosonic string, is unusual, because it has no large transverse dimensions. It is a string moving in one space dimension, and there are neither tachyons nor massless particles. The protostring, derived from our pure spinor string bit model, has 24 Grassmann dimensions, 16 of which could be bosonized to form 8 compactified bosonic dimensions, leaving 8 Grassmann dimensions—the worldsheet content of the superstring. If the transverse space of the protostring could be "decompactified," string bit models might provide an appealing and solid foundation for superstring theory.
Security of quantum bit-string generation
Barrett, Jonathan; Massar, Serge
2004-11-01
We consider the cryptographic task of bit-string generation. This is a generalization of coin tossing in which two mistrustful parties wish to generate a string of random bits such that an honest party can be sure that the other cannot have biased the string too much. We consider a quantum protocol for this task, originally introduced in Phys. Rev. A 69, 022322 (2004), that is feasible with present day technology. We introduce security conditions based on the average bias of the bits and the Shannon entropy of the string. For each, we prove rigorous security bounds for this protocol in both noiseless and noisy conditions under the most general attacks allowed by quantum mechanics. Roughly speaking, in the absence of noise, a cheater can only bias significantly a vanishing fraction of the bits, whereas in the presence of noise, a cheater can bias a constant fraction, with this fraction depending quantitatively on the level of noise. We also discuss classical protocols for the same task, deriving upper bounds on how well a classical protocol can perform. This enables the determination of how much noise the quantum protocol can tolerate while still outperforming classical protocols. We raise several conjectures concerning both quantum and classical possibilities for large n cryptography. An experiment corresponding to the scheme analyzed in this paper has been performed and is reported elsewhere.
Error-resilient compression and transmission of scalable video
NASA Astrophysics Data System (ADS)
Cho, Sungdae; Pearlman, William A.
2000-12-01
Compressed video bitstreams require protection from channel errors in a wireless channel and protection from packet loss in a wired ATM channel. The three-dimensional (3-D) SPIHT coder has proved its efficiency and its real-time capability in compression of video. A forward-error-correcting (FEC) channel (RCPC) code combined with a single ARQ (automatic- repeat-request) proved to be an effective means for protecting the bitstream. There were two problems with this scheme: the noiseless reverse channel ARQ may not be feasible in practice; and, in the absence of channel coding and ARQ, the decoded sequence was hopelessly corrupted even for relatively clean channels. In this paper, we first show how to make the 3-D SPIHT bitstream more robust to channel errors by breaking the wavelet transform into a number of spatio-temporal tree blocks which can be encoded and decoded independently. This procedure brings the added benefit of parallelization of the compression and decompression algorithms. Then we demonstrate the packetization of the bit stream and the reorganization of these packets to achieve scalability in bit rate and/or resolution in addition to robustness. Then we encode each packet with a channel code. Not only does this protect the integrity of the packets in most cases, but it also allows detection of packet decoding failures, so that only the cleanly recovered packets are reconstructed. This procedure obviates ARQ, because the performance is only about 1 dB worse than normal 3-D SPIHT with FEC and ARQ. Furthermore, the parallelization makes possible real-time implementation in hardware and software.
A zero-error operational video data compression system
NASA Technical Reports Server (NTRS)
Kutz, R. L.
1973-01-01
A data compression system has been operating since February 1972, using ATS spin-scan cloud cover data. With the launch of ITOS 3 in October 1972, this data compression system has become the only source of near-realtime very high resolution radiometer image data at the data processing facility. The VHRR image data are compressed and transmitted over a 50 kilobit per second wideband ground link. The goal of the data compression experiment was to send data quantized to six bits at twice the rate possible when no compression is used, while maintaining zero error between the transmitted and reconstructed data. All objectives of the data compression experiment were met, and thus a capability of doubling the data throughput of the system has been achieved.
REVERSIBLE N-BIT TO N-BIT INTEGER HAAR-LIKE TRANSFORMS
Senecal, J G; Duchaineau, M A; Joy, K I
2004-07-26
We introduce TLHaar, an n-bit to n-bit reversible transform similar to the S-transform. TLHaar uses lookup tables that approximate the S-transform, but reorder the coefficients so they fit into n bits. TLHaar is suited for lossless compression in fixed-width channels, such as digital video channels and graphics hardware frame buffers. Tests indicate that when the incoming image data has lines or hard edges TLHaar coefficients compress better than S-transform coefficients. For other types of image data TLHaar coefficients compress up to 2.5% worse than those of the S-transform, depending on the data and the compression method used.
Single-event upset (SEU) in a DRAM with on-chip error correction
NASA Technical Reports Server (NTRS)
Zoutendyk, J. A.; Schwartz, H. R.; Watson, R. K.; Hasnain, Z.; Nevile, L. R.
1987-01-01
Results are given of SEU measurements on 256K dynamic RAMs with on-chip error correction. They are claimed to be the first ever reported. A (12/8) Hamming error-correcting code was incorporated in the layout. Physical separation of the bits in each code word was used to guard against multiple bits being disrupted in any given word. Significant reduction in observed errors is reported.
Reducing Truncation Error In Integer Processing
NASA Technical Reports Server (NTRS)
Thomas, J. Brooks; Berner, Jeffrey B.; Graham, J. Scott
1995-01-01
Improved method of rounding off (truncation of least-significant bits) in integer processing of data devised. Provides for reduction, to extremely low value, of numerical bias otherwise generated by accumulation of truncation errors from many arithmetic operations. Devised for use in integer signal processing, in which rescaling and truncation usually performed to reduce number of bits, which typically builds up in sequence of operations. Essence of method to alternate direction of roundoff (plus, then minus) on alternate occurrences of truncated values contributing to bias.
Errors and Their Mitigation at the Kirchhoff-Law-Johnson-Noise Secure Key Exchange
Saez, Yessica; Kish, Laszlo B.
2013-01-01
A method to quantify the error probability at the Kirchhoff-law-Johnson-noise (KLJN) secure key exchange is introduced. The types of errors due to statistical inaccuracies in noise voltage measurements are classified and the error probability is calculated. The most interesting finding is that the error probability decays exponentially with the duration of the time window of single bit exchange. The results indicate that it is feasible to have so small error probabilities of the exchanged bits that error correction algorithms are not required. The results are demonstrated with practical considerations. PMID:24303033
NASA Astrophysics Data System (ADS)
Tumok, N. Nur
1989-12-01
A variable bit width delta modulator (VBWDM) demodulator was designed, built and tested to achieve voice and music communication using a bandlimited channel. Only baseband modulation is applied to the input signal. Since there is no clock used during the digitizing process at the modulator, no bit synchronization is required for signal recovery in the receiver. The modulator is a hybrid design using 7 linear and 3 digital integrated circuits (IC), and the demodulator uses 2 linear ICs. A lowpass filter (LPF) is used to simulate the channel. The average number of bits sent over the channel is measured with a frequency counter at the output of the modulator. The minimum bandwidth required for the LPF is determined according to the intelligibility of the recovered message. Measurements indicate an average bit rate required for intelligible voice transmission is in the range of 2 to 4 kilobits per seconds (kbps) and between 2 to 5 kbps for music. The channel 3 dB bandwidth required is determined to be 1.5 kilohertzs. Besides the hardware simplicity, VBWDM provides an option for intelligible digitized voice transmission at very low bit rates without requiring synchronization. Another important feature of the modulator design is that no bits are sent when no signal is present at the input which saves transmitter power (important for mobile stations) and reduces probability of intercept and jamming in military applications.
Stereoscopic Visual Attention-Based Regional Bit Allocation Optimization for Multiview Video Coding
NASA Astrophysics Data System (ADS)
Zhang, Yun; Jiang, Gangyi; Yu, Mei; Chen, Ken; Dai, Qionghai
2010-12-01
We propose a Stereoscopic Visual Attention- (SVA-) based regional bit allocation optimization for Multiview Video Coding (MVC) by the exploiting visual redundancies from human perceptions. We propose a novel SVA model, where multiple perceptual stimuli including depth, motion, intensity, color, and orientation contrast are utilized, to simulate the visual attention mechanisms of human visual system with stereoscopic perception. Then, a semantic region-of-interest (ROI) is extracted based on the saliency maps of SVA. Both objective and subjective evaluations of extracted ROIs indicated that the proposed SVA model based on ROI extraction scheme outperforms the schemes only using spatial or/and temporal visual attention clues. Finally, by using the extracted SVA-based ROIs, a regional bit allocation optimization scheme is presented to allocate more bits on SVA-based ROIs for high image quality and fewer bits on background regions for efficient compression purpose. Experimental results on MVC show that the proposed regional bit allocation algorithm can achieve over [InlineEquation not available: see fulltext.]% bit-rate saving while maintaining the subjective image quality. Meanwhile, the image quality of ROIs is improved by [InlineEquation not available: see fulltext.] dB at the cost of insensitive image quality degradation of the background image.
Evaluation of Error-Correcting Codes for Radiation-Tolerant Memory
NASA Astrophysics Data System (ADS)
Jeon, S.; Vijaya Kumar, B. V. K.; Hwang, E.; Cheng, M. K.
2010-05-01
In space, radiation particles can introduce temporary or permanent errors in memory systems. To protect against potential memory faults, either thick shielding or error-correcting codes (ECC) are used by memory modules. Thick shielding translates into increased mass, and conventional ECCs designed for memories are typically capable of correcting only a single error and detecting a double error. Decoding is usually performed through hard decisions where bits are treated as either correct or flipped in polarity. We demonstrate that low-density parity-check (LDPC) codes that are already prevalent in many communication applications can also be used to protect memories in space. Because the achievable code rate monotonically decreases with time due to the accumulation of permanent errors, the achievable rate serves as a useful metric in designing an appropriate ECC. We describe how to compute soft symbol reliabilities on our channel and compare the performance of soft-decision decoding LDPC codes against conventional hard-decision decoding of Reed-Solomon (RS) codes and Bose-Chaudhuri-Hocquenghem (BCH) codes for a specific memory structure.
Error control for reliable digital data transmission and storage systems
NASA Technical Reports Server (NTRS)
Costello, D. J., Jr.; Deng, R. H.
1985-01-01
A problem in designing semiconductor memories is to provide some measure of error control without requiring excessive coding overhead or decoding time. In LSI and VLSI technology, memories are often organized on a multiple bit (or byte) per chip basis. For example, some 256K-bit DRAM's are organized in 32Kx8 bit-bytes. Byte oriented codes such as Reed Solomon (RS) codes can provide efficient low overhead error control for such memories. However, the standard iterative algorithm for decoding RS codes is too slow for these applications. In this paper we present some special decoding techniques for extended single-and-double-error-correcting RS codes which are capable of high speed operation. These techniques are designed to find the error locations and the error values directly from the syndrome without having to use the iterative alorithm to find the error locator polynomial. Two codes are considered: (1) a d sub min = 4 single-byte-error-correcting (SBEC), double-byte-error-detecting (DBED) RS code; and (2) a d sub min = 6 double-byte-error-correcting (DBEC), triple-byte-error-detecting (TBED) RS code.
A constructive inter-track interference coding scheme for bit-patterned media recording system
NASA Astrophysics Data System (ADS)
Arrayangkool, A.; Warisarn, C.; Kovintavewat, P.
2014-05-01
The inter-track interference (ITI) can severely degrade the system performance of bit-patterned media recording (BPMR). One way to alleviate the ITI effect is to encode an input data sequence before recording to avoid some data patterns that easily cause an error at the data detection process. This paper proposes a constructive ITI (CITI) coding scheme for a multi-track multi-head BPMR system to eliminate the data patterns that lead to severe ITI. Numerical results indicate that the system with CITI coding outperforms that without CITI coding, especially when an areal density (AD) is high and/or the position jitter is large. Specifically, for the system without position jitter at bit-error rate of 10-4, the proposed scheme can provide about 3 dB gain at the AD of 2.5 Tb/in.2 over the system without CITI coding.
Earth boring bit with eccentric seal boss
Helmick, J.E.
1981-07-21
A rolling cone cutter earth boring bit is provided with a sealing system that results in the seal being squeezed uniformly around the seal circumference during drilling. The bearing pin seal surface is machined eccentrically to the bearing pin by an amount equal to the radial clearance of the bearing. The bearing pin seal surface is machined about an axis that is offset from the central axis of the bearing pin in the direction of the unloaded side of the bearing pin. When the bit is drilling and the bearing pin is loaded the seal will run on an axis concentric with the axis of the seal surfaces of the bearing pin and the rolling cutter and will see uniform squeeze around its circumference.
Time-dependent study of bit reset
NASA Astrophysics Data System (ADS)
Chiuchiú, D.
2015-02-01
In its most conservative formulation, the Landauer principle states that at least k_BT\\ln2 of heat must be produced to reset one bit. Theoretical derivations of this result for practical systems require complex mathematical tools; additionally, real experiments are sophisticated and sensitive. In the literature, it's then common practice to look for a global heat production of k_BT\\ln2 without further concern for heat exchanges at intermediate times. In this paper we want to recover such kind of description: we take a Brownian particle that moves in a bistable potential as bit. We then consider a reset protocol with a net heat production of k_BT\\ln{2} and study the time evolution of internal energy, work and heat. In particular, we show that these quantities are fully characterized by the changes that the protocol induces over the wells of the bistable potential.
Cosmic Ray Induced Bit-Flipping Experiment
NASA Astrophysics Data System (ADS)
Pu, Ge; Callaghan, Ed; Parsons, Matthew; Cribflex Team
2015-04-01
CRIBFLEX is a novel approach to mid-altitude observational particle physics intended to correlate the phenomena of semiconductor bit-flipping with cosmic ray activity. Here a weather balloon carries a Geiger counter and DRAM memory to various altitudes; the data collected will contribute to the development of memory device protection. We present current progress toward initial flight and data acquisition. This work is supported by the Society of Physics Students with funding from a Chapter Research Award.
Software Operates On Bit-Map Images
NASA Technical Reports Server (NTRS)
Choi, Diana
1992-01-01
PIXTOOLS is software for Silicon Graphics IRIS consisting of thirteen programs plus library for operating on bit-map images. Enables user to create, edit, and save high-resolution images in forms in which displayed on video screens, resize them, and capture them. Eleven programs print information and read and write files. Two offer graphical interfaces. Menus enable manipulation of images and background color and saving of an image screen to file. Written in C.
NSC 800, 8-bit CMOS microprocessor
NASA Technical Reports Server (NTRS)
Suszko, S. F.
1984-01-01
The NSC 800 is an 8-bit CMOS microprocessor manufactured by National Semiconductor Corp., Santa Clara, California. The 8-bit microprocessor chip with 40-pad pin-terminals has eight address buffers (A8-A15), eight data address -- I/O buffers (AD(sub 0)-AD(sub 7)), six interrupt controls and sixteen timing controls with a chip clock generator and an 8-bit dynamic RAM refresh circuit. The 22 internal registers have the capability of addressing 64K bytes of memory and 256 I/O devices. The chip is fabricated on N-type (100) silicon using self-aligned polysilicon gates and local oxidation process technology. The chip interconnect consists of four levels: Aluminum, Polysi 2, Polysi 1, and P(+) and N(+) diffusions. The four levels, except for contact interface, are isolated by interlevel oxide. The chip is packaged in a 40-pin dual-in-line (DIP), side brazed, hermetically sealed, ceramic package with a metal lid. The operating voltage for the device is 5 V. It is available in three operating temperature ranges: 0 to +70 C, -40 to +85 C, and -55 to +125 C. Two devices were submitted for product evaluation by F. Stott, MTS, JPL Microprocessor Specialist. The devices were pencil-marked and photographed for identification.
Junk basket, bit and reamer stabilizer
Garrett, W.R.
1980-08-19
A metal cup with an apertured bottom provides a junk basket. The cup is spindled on the pin of a drill bit, e.g., a tungsten carbide insert roller cone bit, the bottom edge being releasably clamped between the pin shoulder and the shoulder formed by the mouth of the box on the member forming the lower end of the drill stem, e.g., a roller reamer. The connection between the pin and box and cup form a rotary shouldered connection, the pin shoulder and/or box mouth being cut back providing a longer pin neck or shallower box to accommodate the cup. Every time the bit is removed from the stem, the interiorly upwardly flaring cup is automatically dumped. In a modification, especially for small diameter holes, in order to provide space for junk to move both up outside the cup and down into the cup, the box on the adjacent drill stem member can be fluted, e.g., with arcuate vertical section milled slots extending from above to below the rim of the cup to provide entrance for junk, so maximum exterior annulus space is left for upflow of junk; alternatively the cup aperture can be eccentric, so the space around the outside of the cup is large at one sector and the space around the box inside the cup is large at the opposite sector.
An Optical Bit-Counting Algorithm
NASA Technical Reports Server (NTRS)
Mack, Marilyn; Lapir, Gennadi M.; Berkovich, Simon
2000-01-01
This paper addresses the omnipresent problem of counting bits - an operation discussed since the very early stages of the establishing of computer science. The need for a quick bit-counting method acquires a special significance with the proliferation of search engines on the Internet. It arises in several other computer applications. This is especially true in information retrieval in which an array of binary vectors is used to represent a characteristic function (CF) of a set of qualified documents. The number of "I"s in the CF equals the cardinality of the set. The process of repeated evaluations of this cardinality is a pivotal point in choosing a rational strategy for deciding whether to constrain or broaden the search criteria to ensure selection of the desired items. Another need for bit-counting occurs when trying to determine the differences between given files, (images or text), in terms of the Hamming distance. An Exclusive OR operation applied to a pair of files results in a binary vector array of mismatches that must be counted.
Acquisition and Retaining Granular Samples via a Rotating Coring Bit
NASA Technical Reports Server (NTRS)
Bar-Cohen, Yoseph; Badescu, Mircea; Sherrit, Stewart
2013-01-01
This device takes advantage of the centrifugal forces that are generated when a coring bit is rotated, and a granular sample is entered into the bit while it is spinning, making it adhere to the internal wall of the bit, where it compacts itself into the wall of the bit. The bit can be specially designed to increase the effectiveness of regolith capturing while turning and penetrating the subsurface. The bit teeth can be oriented such that they direct the regolith toward the bit axis during the rotation of the bit. The bit can be designed with an internal flute that directs the regolith upward inside the bit. The use of both the teeth and flute can be implemented in the same bit. The bit can also be designed with an internal spiral into which the various particles wedge. In another implementation, the bit can be designed to collect regolith primarily from a specific depth. For that implementation, the bit can be designed such that when turning one way, the teeth guide the regolith outward of the bit and when turning in the opposite direction, the teeth will guide the regolith inward into the bit internal section. This mechanism can be implemented with or without an internal flute. The device is based on the use of a spinning coring bit (hollow interior) as a means of retaining granular sample, and the acquisition is done by inserting the bit into the subsurface of a regolith, soil, or powder. To demonstrate the concept, a commercial drill and a coring bit were used. The bit was turned and inserted into the soil that was contained in a bucket. While spinning the bit (at speeds of 600 to 700 RPM), the drill was lifted and the soil was retained inside the bit. To prove this point, the drill was turned horizontally, and the acquired soil was still inside the bit. The basic theory behind the process of retaining unconsolidated mass that can be acquired by the centrifugal forces of the bit is determined by noting that in order to stay inside the interior of the bit, the
System Measures Errors Between Time-Code Signals
NASA Technical Reports Server (NTRS)
Cree, David; Venkatesh, C. N.
1993-01-01
System measures timing errors between signals produced by three asynchronous time-code generators. Errors between 1-second clock pulses resolved to 2 microseconds. Basic principle of computation of timing errors as follows: central processing unit in microcontroller constantly monitors time data received from time-code generators for changes in 1-second time-code intervals. In response to any such change, microprocessor buffers count of 16-bit internal timer.
Device-independent bit commitment based on the CHSH inequality
NASA Astrophysics Data System (ADS)
Aharon, N.; Massar, S.; Pironio, S.; Silman, J.
2016-02-01
Bit commitment and coin flipping occupy a unique place in the device-independent landscape, as the only device-independent protocols thus far suggested for these tasks are reliant on tripartite GHZ correlations. Indeed, we know of no other bipartite tasks, which admit a device-independent formulation, but which are not known to be implementable using only bipartite nonlocality. Another interesting feature of these protocols is that the pseudo-telepathic nature of GHZ correlations—in contrast to the generally statistical character of nonlocal correlations, such as those arising in the violation of the CHSH inequality—is essential to their formulation and analysis. In this work, we present a device-independent bit commitment protocol based on CHSH testing, which achieves the same security as the optimal GHZ-based protocol, albeit at the price of fixing the time at which Alice reveals her commitment. The protocol is analyzed in the most general settings, where the devices are used repeatedly and may have long-term quantum memory. We also recast the protocol in a post-quantum setting where both honest and dishonest parties are restricted only by the impossibility of signaling, and find that overall the supra-quantum structure allows for greater security.
Challenges and promises in the fabrication of bit patterned media
NASA Astrophysics Data System (ADS)
Moneck, Matthew T.; Zhu, Jian-Gang
2010-09-01
Bit patterned media (BPM) is one of the promising technologies for ultra-high density storage in future hard disk drives. However, there are many challenges in fabricating BPM. In particular, applications with area density much greater than 1 Tbit/in2 require magnetic bits to be at sub-10 nm dimensions. Etching at these scales is difficult to achieve with conventional ion milling techniques. Instead, reactive ion etching (RIE) techniques must be developed to meet the challenge. In this work, research is presented on the development of a methanol based RIE scheme for fabricating BPM at ultra-high area densities. The paper will discuss the ability of methanol RIE to etch magnetic and nonmagnetic films in both the parallel plate and inductively coupled plasma (ICP) RIE configurations, as well as the advantages of both configurations over Ar ion milling, including enhanced selectivity, minimal redeposition, and less etch induced damage or erosion. We demonstrate the ability to etch sub-20 nm features in commercially available CoCrPt based perpendicular recording media and NiFe with selectivity greater than 10:1 relative to mask materials, such as Ta, TaNx, Ti, and SiNx. These results, the promises of such a technique, and the feasibility of sub-10 nm scale etching are discussed in detail.
Techniques for containing error propagation in compression/decompression schemes
NASA Technical Reports Server (NTRS)
Kobler, Ben
1991-01-01
Data compression has the potential for increasing the risk of data loss. It can also cause bit error propagation, resulting in catastrophic failures. There are a number of approaches possible for containing error propagation due to data compression: (1) data retransmission; (2) data interpolation; (3) error containment; and (4) error correction. The most fruitful techniques will be ones where error containment and error correction are integrated with data compression to provide optimal performance for both. The error containment characteristics of existing compression schemes should be analyzed for their behavior under different data and error conditions. The error tolerance requirements of different data sets need to be understood, so guidelines can then be developed for matching error requirements to suitable compression algorithms.
Coherent WDM, toward > 1 bit/s/Hz information spectral density
NASA Astrophysics Data System (ADS)
Ellis, Andrew D.; Gunning, Fatima C.
2005-06-01
Many approaches to achieving high information spectral density (ISD), have been reported recently. The standard non-return-to-zero (NRZ) format, which offers a base line performance around 0.4 bit/s/Hz, may be enhanced using a variety of techniques, including: pre-filtering within the transmitter, multi-level modulation formats and polarisation interleaving or multiplexing. These techniques either increase the information per channel (multi-level formats and polarization multiplexing) or minimise interferometric cross talk (pre-filtering and polarisation interleaving) and result in ISDs around 0.8 bit/s/Hz. Combinations of these techniques have been used to provide ISDs of up to 1.6 bit/s/Hz. In this paper we propose a new technique, which we call Coherent WDM (CoWDM), to increase the ISD of NRZ binary coded signals in a single polarisation from 0.4 to 1 bit/s/Hz whilst simultaneously eliminating the need for pre-filters within the transmitter. Phase control within the transmitter is used to achieve precise control of interferometric cross talk. This allows the use of stronger demultiplexing filters at the receiver, and provides optimum performance when the bit rate equals the channel spacing, giving an ISD of 1 bit/s/Hz. This interference control may be achieved by controlling the phase of each laser individually with optical phase locked loops, or by replacing the typical bank of lasers with one or more coherent comb sources, and encoding data using an array of modulators that preserves this relative optical phase. Since optical filtering is not required in the transmitter, stronger optical filters may be used to demultiplex the individual WDM channels at the receiver, further reducing cross talk.
Lathe tool bit and holder for machining fiberglass materials
NASA Technical Reports Server (NTRS)
Winn, L. E. (Inventor)
1972-01-01
A lathe tool and holder combination for machining resin impregnated fiberglass cloth laminates is described. The tool holder and tool bit combination is designed to accommodate a conventional carbide-tipped, round shank router bit as the cutting medium, and provides an infinite number of cutting angles in order to produce a true and smooth surface in the fiberglass material workpiece with every pass of the tool bit. The technique utilizes damaged router bits which ordinarily would be discarded.
Method to manufacture bit patterned magnetic recording media
Raeymaekers, Bart; Sinha, Dipen N
2014-05-13
A method to increase the storage density on magnetic recording media by physically separating the individual bits from each other with a non-magnetic medium (so-called bit patterned media). This allows the bits to be closely packed together without creating magnetic "cross-talk" between adjacent bits. In one embodiment, ferromagnetic particles are submerged in a resin solution, contained in a reservoir. The bottom of the reservoir is made of piezoelectric material.
NASA Technical Reports Server (NTRS)
Folkner, W. M.; Finger, M. H.
1990-01-01
Future missions to the outer solar system or human exploration of Mars may use telemetry systems based on optical rather than radio transmitters. Pulsed laser transmission can be used to deliver telemetry rates of about 100 kbits/sec with an efficiency of several bits for each detected photon. Navigational observables that can be derived from timing pulsed laser signals are discussed. Error budgets are presented based on nominal ground stations and spacecraft-transceiver designs. Assuming a pulsed optical uplink signal, two-way range accuracy may approach the few centimeter level imposed by the troposphere uncertainty. Angular information can be achieved from differenced one-way range using two ground stations with the accuracy limited by the length of the available baseline and by clock synchronization and troposphere errors. A method of synchronizing the ground station clocks using optical ranging measurements is presented. This could allow differenced range accuracy to reach the few centimeter troposphere limit.
Laboratory and field testing of improved geothermal rock bits
Hendrickson, R.R.; Jones, A.H.; Winzenried, R.W.; Maish, A.B.
1980-07-01
The development and testing of 222 mm (8-3/4 inch) unsealed, insert type, medium hard formation, high-temperature bits are described. The new bits were fabricated by substituting improved materials in critical bit components. These materials were selected on bases of their high temperature properties, machinability, and heat treatment response. Program objectives required that both machining and heat treating could be accomplished with existing rock bit production equipment. Two types of experimental bits were subjected to laboratory air drilling tests at 250/sup 0/C (482/sup 0/F) in cast iron. These tests indicated field testing could be conducted without danger to the hole, and that bearing wear would be substantially reduced. Six additional experimental bits, and eight conventional bits were then subjected to air drilling a 240/sup 0/C (464/sup 0/F) in Francisan Graywacke at The Geysers, CA. The materials selected improved roller wear by 200%, friction-pin wear by 150%, and lug wear by 150%. Geysers drilling performances compared directly to conventional bits indicate that in-gage drilling life was increased by 70%. All bits at The Geysers are subjected to reaming out-of-gage hole prior to drilling. Under these conditions the experimental bits showed a 30% increase in usable hole over the conventional bits. These tests demonstrated a potential well cost reduction of 4 to 8%. Savings of 12% are considered possible with drilling procedures optimized for the experimental bits.
Reversible n-Bit to n-Bit Integer Haar-Like Transforms
Senecal, J; Duchaineau, M; Joy, K I
2003-11-03
We introduce a wavelet-like transform similar to the Haar transform, but with the properties that it packs the results into the same number of bits as the original data, and is reversible. Our method, called TLHaar, uses table lookups to replace the averaging, differencing, and bit shifting performed in a Haar IntegerWavelet Transform (IWT). TLHaar maintains the same coefficient magnitude relationships for the low- and high-pass coefficients as true Haar, but reorders them to fit into the same number of bits as the input signal, thus eliminating the sign bit that is added to the Haar IWT output coefficients. Eliminating the sign bit avoids using extra memory and speeds the transform process. We tested TLHaar on a variety of image types, and when compared to the Haar IWT TLHaar is significantly faster. For image data with lines or hard edges TLHaar coefficients compress better than those of the Haar IWT. Due to its speed TLHaar is suitable for streaming hardware implementations with fixed data sizes, such as DVI channels.
Choi, Woo Young; Han, Jae Hwan; Cha, Tae Min
2016-05-01
Multi-bit nano-electromechanical (NEM) nonvolatile memory cells such as T cells were proposed for higher memory density. However, they suffered from bit-to-bit interference (BI). In order to suppress BI without sacrificing cell size, this paper proposes zigzag T cell structures. The BI suppression of the proposed zigzag T cell is verified by finite-element modeling (FEM). Based on the FEM results, the design of zigzag T cells is optimized. PMID:27483893
Retransmission error control with memory
NASA Technical Reports Server (NTRS)
Sindhu, P. S.
1977-01-01
In this paper, an error control technique that is a basic improvement over automatic-repeat-request ARQ is presented. Erroneously received blocks in an ARQ system are used for error control. The technique is termed ARQ-with-memory (MRQ). The general MRQ system is described, and simple upper and lower bounds are derived on the throughput achievable by MRQ. The performance of MRQ with respect to throughput, message delay and probability of error is compared to that of ARQ by simulating both systems using error data from a VHF satellite channel being operated in the ALOHA packet broadcasting mode.
Modeling micro-electronics drill bit behavior with ABAQUS Standard
Anderson, C.A.; Ricketson, E.
1997-06-01
Modeling of drill bit behavior under applied forces as well as modeling of the drilling process itself can aid in the understanding of the relative importance of the various drill bit process parameters and can eventually lead to improved drill bit designs. In this paper the authors illustrate the application of ABAQUS Standard to the stress and deformation analysis of micro-electronics drill bits that are used in manufacturing printed circuit boards. Effects of varying point geometry, web taper and flute length on the stress and deformation in a drill bit are illustrated.
A novel bit-quad-based Euler number computing algorithm.
Yao, Bin; He, Lifeng; Kang, Shiying; Chao, Yuyan; Zhao, Xiao
2015-01-01
The Euler number of a binary image is an important topological property in computer vision and pattern recognition. This paper proposes a novel bit-quad-based Euler number computing algorithm. Based on graph theory and analysis on bit-quad patterns, our algorithm only needs to count two bit-quad patterns. Moreover, by use of the information obtained during processing the previous bit-quad, the average number of pixels to be checked for processing a bit-quad is only 1.75. Experimental results demonstrated that our method outperforms significantly conventional Euler number computing algorithms. PMID:26636023
Cosmic Ray Induced Bit-Flipping Experiment
NASA Astrophysics Data System (ADS)
Callaghan, Edward; Parsons, Matthew
2015-04-01
CRIBFLEX is a novel approach to mid-altitude observational particle physics intended to correlate the phenomena of semiconductor bit-flipping with cosmic ray activity. Here a weather balloon carries a Geiger counter and DRAM memory to various altitudes; the data collected will contribute to the development of memory device protection. We present current progress toward initial flight and data acquisition. This work is supported by the Society of Physics Students with funding from a Chapter Research Award. Supported by a Society of Physics Students Chapter Research Award.
An error control system with multiple-stage forward error corrections
NASA Technical Reports Server (NTRS)
Takata, Toyoo; Fujiwara, Toru; Kasami, Tadao; Lin, Shu
1990-01-01
A robust error-control coding system is presented. This system is a cascaded FEC (forward error control) scheme supported by parity retransmissions for further error correction in the erroneous data words. The error performance and throughput efficiency of the system are analyzed. Two specific examples of the error-control system are studied. The first example does not use an inner code, and the outer code, which is not interleaved, is a shortened code of the NASA standard RS code over GF(28). The second example, as proposed for NASA, uses the same shortened RS code as the base outer code C2, except that it is interleaved to a depth of 2. It is shown that both examples provide high reliability and throughput efficiency even for high channel bit-error rates in the range of 0.01.
Triple-Error-Correcting Codec ASIC
NASA Technical Reports Server (NTRS)
Jones, Robert E.; Segallis, Greg P.; Boyd, Robert
1994-01-01
Coder/decoder constructed on single integrated-circuit chip. Handles data in variety of formats at rates up to 300 Mbps, correcting up to 3 errors per data block of 256 to 512 bits. Helps reduce cost of transmitting data. Useful in many high-data-rate, bandwidth-limited communication systems such as; personal communication networks, cellular telephone networks, satellite communication systems, high-speed computing networks, broadcasting, and high-reliability data-communication links.
New Mechanisms of rock-bit wear in geothermal wells
Macini, Paolo
1996-01-24
This paper presents recent results of an investigation on failure mode and wear of rock-bits used to drill geothermal wells located in the area of Larderello (Italy). A new wear mechanism, conceived from drilling records and dull bit evaluation analysis, has been identified and a particular configuration of rock-bit has been developed and tested in order to reduce drilling costs. The role of high Bottom Hole Temperature (BHT) on rock-bit performances seems not yet very well understood: so far, only drillability and formation abrasiveness are generally considered to account for poor drilling performances. In this paper, the detrimental effects of high BHT on sealing and reservoir system of Friction Bearing Rock-bits (FBR) have been investigated, and a new bearing wear pattern for FBR's run in high BHT holes has been identified and further verified via laboratory inspections on dull bits. A novel interpretation of flat worn cutting structure has been derived from the above wear pattern, suggesting the design of a particular bit configuration. Test bits, designed in the light of the above criteria, have been prepared and field tested successfully. The paper reports the results of these tests, which yielded a new rock-bit application, today considered as a standad practice in Italian geothermal fields. This application suggests that the correct evaluation of rock-bit wear can help to improve the overall drilling performances and to minimize drilling problems through a better interpretation of the relationships amongst rock-bits, formation properties and downhole temperature.
Carrier Synchronization for 3-and 4-bit-per-Symbol Optical Transmission
NASA Astrophysics Data System (ADS)
Ip, Ezra; Kahn, Joseph M.
2005-12-01
We investigate carrier synchronization for coherent detection of optical signals encoding 3 and 4 bits/symbol. We consider the effects of laser phase noise and of additive white Gaussian noise (AWGN), which can arise from local oscillator (LO) shot noise or LO-spontaneous beat noise. We identify 8-and 16-ary quadrature amplitude modulation (QAM) schemes that perform well when the receiver phase-locked loop (PLL) tracks the instantaneous signal phase with moderate phase error. We propose implementations of 8-and 16-QAM transmitters using Mach-Zehnder (MZ) modulators. We outline a numerical method for computing the bit error rate (BER) of 8-and 16-QAM in the presence of AWGN and phase error. It is found that these schemes can tolerate phase-error standard deviations of 2.48° and 1.24°, respectively, for a power penalty of 0.5 dB at a BER of 10-9. We propose a suitable PLL design and analyze its performance, taking account of laser phase noise, AWGN, and propagation delay within the PLL. Our analysis shows that the phase error depends on the constellation penalty, which is the mean power of constellation symbols times the mean inverse power. We establish a procedure for finding the optimal PLL natural frequency, and determine tolerable laser linewidths and PLL propagation delays. For zero propagation delay, 8-and 16-QAM can tolerate linewidth-to-bit-rate ratios of 1.8 × 10-5 and 1.4 × 10-6, respectively, assuming a total penalty of 1.0 dB.
NASA Astrophysics Data System (ADS)
Li, Tsung-Ling; Sakai, Shin; Kawada, Shun; Goda, Yasuyuki; Wakashima, Shunichi; Kuroda, Rihito; Sugawa, Shigetoshi
2013-04-01
In this paper, a column-parallel hybrid analog-to-digital converter (ADC) architecture taking the advantages of both successive-approximation-register (SAR) and single-slope (SS) architectures has been developed for CMOS image sensors. The proposed architecture achieves high conversion speed and low power consumption without requiring a high clock frequency and a large number of capacitors. Moreover, an error correction methodology has been presented to calibrate capacitance mismatches in a SAR capacitor array for linearity improvement. An 11-bit hybrid prototype ADC has been implemented in a 0.18-µm 1-poly 5-metal standard CMOS process. The conversion time is 1.225 µs with a maximum operation clock frequency of 40 MHz and it consumes 48 µW. With the proposed error correction, the measured differential nonlinearity (DNL) and integral nonlinearity (INL) are +0.40/-0.44 least significant bit (LSB) and +1.21/-1.12 LSB, respectively.
Object tracking based on bit-planes
NASA Astrophysics Data System (ADS)
Li, Na; Zhao, Xiangmo; Liu, Ying; Li, Daxiang; Wu, Shiqian; Zhao, Feng
2016-01-01
Visual object tracking is one of the most important components in computer vision. The main challenge for robust tracking is to handle illumination change, appearance modification, occlusion, motion blur, and pose variation. But in surveillance videos, factors such as low resolution, high levels of noise, and uneven illumination further increase the difficulty of tracking. To tackle this problem, an object tracking algorithm based on bit-planes is proposed. First, intensity and local binary pattern features represented by bit-planes are used to build two appearance models, respectively. Second, in the neighborhood of the estimated object location, a region that is most similar to the models is detected as the tracked object in the current frame. In the last step, the appearance models are updated with new tracking results in order to deal with environmental and object changes. Experimental results on several challenging video sequences demonstrate the superior performance of our tracker compared with six state-of-the-art tracking algorithms. Additionally, our tracker is more robust to low resolution, uneven illumination, and noisy video sequences.
Statistical mechanics of error-correcting codes
NASA Astrophysics Data System (ADS)
Kabashima, Y.; Saad, D.
1999-01-01
We investigate the performance of error-correcting codes, where the code word comprises products of K bits selected from the original message and decoding is carried out utilizing a connectivity tensor with C connections per index. Shannon's bound for the channel capacity is recovered for large K and zero temperature when the code rate K/C is finite. Close to optimal error-correcting capability is obtained for finite K and C. We examine the finite-temperature case to assess the use of simulated annealing for decoding and extend the analysis to accommodate other types of noisy channels.
Serialized Quantum Error Correction Protocol for High-Bandwidth Quantum Repeaters
NASA Astrophysics Data System (ADS)
Glaudell, Andrew; Waks, Edo; Taylor, Jacob
Advances in single-photon creation, transmission, and detection suggest that sending quantum information over optical fibers may have low enough losses to be overcome using quantum error correction. Such error-corrected communication is equivalent to a novel quantum repeater scheme, but crucial questions regarding implementation and system requirements remain open. In this talk, I will show that long-range entangled bit generation with rates approaching 108 entangled bits per second may be possible using a completely serialized protocol, in which photons are generated, entangled, and error corrected via sequential, one-way interactions with as few matter qubits as possible. Provided loss and error rates of the required elements are below the threshold for quantum error correction, this scheme demonstrates improved performance over transmission of single photons. We find improvement in entangled bit rates at large distances using this serial protocol and various quantum error correcting codes.
Reed Solomon codes for error control in byte organized computer memory systems
NASA Technical Reports Server (NTRS)
Lin, S.; Costello, D. J., Jr.
1984-01-01
A problem in designing semiconductor memories is to provide some measure of error control without requiring excessive coding overhead or decoding time. In LSI and VLSI technology, memories are often organized on a multiple bit (or byte) per chip basis. For example, some 256K-bit DRAM's are organized in 32Kx8 bit-bytes. Byte oriented codes such as Reed Solomon (RS) codes can provide efficient low overhead error control for such memories. However, the standard iterative algorithm for decoding RS codes is too slow for these applications. Some special decoding techniques for extended single-and-double-error-correcting RS codes which are capable of high speed operation are presented. These techniques are designed to find the error locations and the error values directly from the syndrome without having to use the iterative algorithm to find the error locator polynomial.
Computer Series, 17: Bits and Pieces, 5.
ERIC Educational Resources Information Center
Moore, John W., Ed.
1981-01-01
Contains short descriptions of computer programs or hardware that simulate laboratory instruments or results of kinetics experiments, including ones that include experiment error, numerical simulation, first-order kinetic mechanisms, a game for decisionmaking, and simulated mass spectrophotometers. (CS)
Progress in the Advanced Synthetic-Diamond Drill Bit Program
Glowka, D.A.; Dennis, T.; Le, Phi; Cohen, J.; Chow, J.
1995-11-01
Cooperative research is currently underway among five drill bit companies and Sandia National Laboratories to improve synthetic-diamond drill bits for hard-rock applications. This work, sponsored by the US Department of Energy and individual bit companies, is aimed at improving performance and bit life in harder rock than has previously been possible to drill effectively with synthetic-diamond drill bits. The goal is to extend to harder rocks the economic advantages seen in using synthetic-diamond drill bits in soft and medium rock formations. Four projects are being conducted under this research program. Each project is investigating a different area of synthetic diamond bit technology that builds on the current technology base and market interests of the individual companies involved. These projects include: optimization of the PDC claw cutter; optimization of the Track-Set PDC bit; advanced TSP bit development; and optimization of impregnated-diamond drill bits. This paper describes the progress made in each of these projects to date.
Errors in thermochromic liquid crystal thermometry
NASA Astrophysics Data System (ADS)
Wiberg, Roland; Lior, Noam
2004-09-01
This article experimentally investigates and assesses the errors that may be incurred in the hue-based thermochromic liquid crystal thermochromic liquid crystal (TLC) method, and their causes. The errors include response time, hysteresis, aging, surrounding illumination disturbance, direct illumination and viewing angle, amount of light into the camera, TLC thickness, digital resolution of the image conversion system, and measurement noise. Some of the main conclusions are that: (1) The 3×8 bits digital representation of the red green and blue TLC color values produces a temperature measurement error of typically 1% of the TLC effective temperature range, (2) an eight-fold variation of the light intensity into the camera produced variations, which were not discernable from the digital resolution error, (3) this temperature depends on the TLC film thickness, and (4) thicker films are less susceptible to aging and thickness nonuniformities.
Asymmetric soft-error resistant memory
NASA Technical Reports Server (NTRS)
Buehler, Martin G. (Inventor); Perlman, Marvin (Inventor)
1991-01-01
A memory system is provided, of the type that includes an error-correcting circuit that detects and corrects, that more efficiently utilizes the capacity of a memory formed of groups of binary cells whose states can be inadvertently switched by ionizing radiation. Each memory cell has an asymmetric geometry, so that ionizing radiation causes a significantly greater probability of errors in one state than in the opposite state (e.g., an erroneous switch from '1' to '0' is far more likely than a switch from '0' to'1'. An asymmetric error correcting coding circuit can be used with the asymmetric memory cells, which requires fewer bits than an efficient symmetric error correcting code.
A fast rise-rate, adjustable-mass-bit gas puff valve for energetic pulsed plasma experiments
Loebner, Keith T. K. Underwood, Thomas C.; Cappelli, Mark A.
2015-06-15
A fast rise-rate, variable mass-bit gas puff valve based on the diamagnetic repulsion principle was designed, built, and experimentally characterized. The ability to hold the pressure rise-rate nearly constant while varying the total overall mass bit was achieved via a movable mechanical restrictor that is accessible while the valve is assembled and pressurized. The rise-rates and mass-bits were measured via piezoelectric pressure transducers for plenum pressures between 10 and 40 psig and restrictor positions of 0.02-1.33 cm from the bottom of the linear restrictor travel. The mass-bits were found to vary linearly with the restrictor position at a given plenum pressure, while rise-rates varied linearly with plenum pressure but exhibited low variation over the range of possible restrictor positions. The ability to change the operating regime of a pulsed coaxial plasma deflagration accelerator by means of altering the valve parameters is demonstrated.
A fast rise-rate, adjustable-mass-bit gas puff valve for energetic pulsed plasma experiments
NASA Astrophysics Data System (ADS)
Loebner, Keith T. K.; Underwood, Thomas C.; Cappelli, Mark A.
2015-06-01
A fast rise-rate, variable mass-bit gas puff valve based on the diamagnetic repulsion principle was designed, built, and experimentally characterized. The ability to hold the pressure rise-rate nearly constant while varying the total overall mass bit was achieved via a movable mechanical restrictor that is accessible while the valve is assembled and pressurized. The rise-rates and mass-bits were measured via piezoelectric pressure transducers for plenum pressures between 10 and 40 psig and restrictor positions of 0.02-1.33 cm from the bottom of the linear restrictor travel. The mass-bits were found to vary linearly with the restrictor position at a given plenum pressure, while rise-rates varied linearly with plenum pressure but exhibited low variation over the range of possible restrictor positions. The ability to change the operating regime of a pulsed coaxial plasma deflagration accelerator by means of altering the valve parameters is demonstrated.
Proposed first-generation WSQ bit allocation procedure
Bradley, J.N.; Brislawn, C.M.
1993-09-08
The Wavelet/Scalar Quantization (WSQ) gray-scale fingerprint image compression algorithm involves a symmetric wavelet transform (SWT) image decomposition followed by uniform scalar quantization of each subband. The algorithm is adaptive insofar as the bin widths for the scalar quantizers are image-specific and are included in the compressed image format. Since the decoder requires only the actual bin width values -- but not the method by which they were computed -- the standard allows for future refinements of the WSQ algorithm by improving the method used to select the scalar quantizer bin widths. This report proposes a bit allocation procedure for use with the first-generation WSQ encoder. In previous work a specific formula is provided for the relative sizes of the scalar quantizer bin widths in terms of the variances of the SWT subbands. An explicit specification for the constant of proportionality, q, that determines the absolute bin widths was not given. The actual compression ratio produced by the WSQ algorithm will generally vary from image to image depending on the amount of coding gain obtained by the run-length and Huffman coding, stages of the algorithm, but testing performed by the FBI established that WSQ compression produces archival quality images at compression ratios of around 20 to 1. The bit allocation procedure described in this report possesses a control parameter, r, that can be set by the user to achieve a predetermined amount of lossy compression, effectively giving the user control over the amount of distortion introduced by quantization noise. The variability observed in final compression ratios is thus due only to differences in lossless coding gain from image to image, chiefly a result of the varying amounts of blank background surrounding the print area in the images. Experimental results are presented that demonstrate the proposed method`s effectiveness.
Speech coding at low to medium bit rates
NASA Astrophysics Data System (ADS)
Leblanc, Wilfred Paul
1992-09-01
Improved search techniques coupled with improved codebook design methodologies are proposed to improve the performance of conventional code-excited linear predictive coders for speech. Improved methods for quantizing the short term filter are developed by employing a tree search algorithm and joint codebook design to multistage vector quantization. Joint codebook design procedures are developed to design locally optimal multistage codebooks. Weighting during centroid computation is introduced to improve the outlier performance of the multistage vector quantizer. Multistage vector quantization is shown to be both robust against input characteristics and in the presence of channel errors. Spectral distortions of about 1 dB are obtained at rates of 22-28 bits/frame. Structured codebook design procedures for excitation in code-excited linear predictive coders are compared to general codebook design procedures. Little is lost using significant structure in the excitation codebooks while greatly reducing the search complexity. Sparse multistage configurations are proposed for reducing computational complexity and memory size. Improved search procedures are applied to code-excited linear prediction which attempt joint optimization of the short term filter, the adaptive codebook, and the excitation. Improvements in signal to noise ratio of 1-2 dB are realized in practice.
Modeling for write synchronization in bit patterned media recording
NASA Astrophysics Data System (ADS)
Lin, Maria Yu; Chan, Kheong Sann; Chua, Melissa; Zhang, Songhua; Kui, Cai; Elidrissi, Moulay Rachid
2012-04-01
Bit patterned media recording (BPMR) is a contender for next generation technology after conventional granular magnetic recording (CGMR) can no longer sustain the continued areal density growth. BPMR has several technological hurdles that need to be overcome, among them is solving the problem of write synchronization. With CGMR, grains are randomly distributed and occur almost all over the media. In contrast, BPMR has grains patterned into a regular lattice on the media with an approximate 50% duty cycle. Hence only about a quarter of the area is filled with magnetic material. During writing, the clock must be synchronized to the islands or the written in error rate becomes unacceptably large and the system fails. Maintaining synchronization during writing is a challenge as the system is not able to read and write simultaneously. Hence reading must occur periodically between the writing frequently enough to re-synchronize the writing clock to the islands. In this work, we study the requirements on the lengths of the synchronization and data sectors in a BPMR system using an advanced model for BPMR, and taking into consideration different spindle motor speed variations, which is the main cause of the mis-synchronization.
Impossibility of Growing Quantum Bit Commitments
NASA Astrophysics Data System (ADS)
Winkler, Severin; Tomamichel, Marco; Hengl, Stefan; Renner, Renato
2011-08-01
Quantum key distribution (QKD) is often, more correctly, called key growing. Given a short key as a seed, QKD enables two parties, connected by an insecure quantum channel, to generate a secret key of arbitrary length. Conversely, no key agreement is possible without access to an initial key. Here, we consider another fundamental cryptographic task, commitments. While, similar to key agreement, commitments cannot be realized from scratch, we ask whether they may be grown. That is, given the ability to commit to a fixed number of bits, is there a way to augment this to commitments to strings of arbitrary length? Using recently developed information-theoretic techniques, we answer this question in the negative.
Second quantization in bit-string physics
NASA Technical Reports Server (NTRS)
Noyes, H. Pierre
1993-01-01
Using a new fundamental theory based on bit-strings, a finite and discrete version of the solutions of the free one particle Dirac equation as segmented trajectories with steps of length h/mc along the forward and backward light cones executed at velocity +/- c are derived. Interpreting the statistical fluctuations which cause the bends in these segmented trajectories as emission and absorption of radiation, these solutions are analogous to a fermion propagator in a second quantized theory. This allows us to interpret the mass parameter in the step length as the physical mass of the free particle. The radiation in interaction with it has the usual harmonic oscillator structure of a second quantized theory. How these free particle masses can be generated gravitationally using the combinatorial hierarchy sequence (3,10,137,2(sup 127) + 136), and some of the predictive consequences are sketched.
Single Abrikosov vortices as quantized information bits
NASA Astrophysics Data System (ADS)
Golod, T.; Iovan, A.; Krasnov, V. M.
2015-10-01
Superconducting digital devices can be advantageously used in future supercomputers because they can greatly reduce the dissipation power and increase the speed of operation. Non-volatile quantized states are ideal for the realization of classical Boolean logics. A quantized Abrikosov vortex represents the most compact magnetic object in superconductors, which can be utilized for creation of high-density digital cryoelectronics. In this work we provide a proof of concept for Abrikosov-vortex-based random access memory cell, in which a single vortex is used as an information bit. We demonstrate high-endurance write operation and two different ways of read-out using a spin valve or a Josephson junction. These memory cells are characterized by an infinite magnetoresistance between 0 and 1 states, a short access time, a scalability to nm sizes and an extremely low write energy. Non-volatility and perfect reproducibility are inherent for such a device due to the quantized nature of the vortex.
Error control techniques for satellite and space communications
NASA Technical Reports Server (NTRS)
Costello, Daniel J., Jr.
1995-01-01
This report focuses on the results obtained during the PI's recent sabbatical leave at the Swiss Federal Institute of Technology (ETH) in Zurich, Switzerland, from January 1, 1995 through June 30, 1995. Two projects investigated various properties of TURBO codes, a new form of concatenated coding that achieves near channel capacity performance at moderate bit error rates. The performance of TURBO codes is explained in terms of the code's distance spectrum. These results explain both the near capacity performance of the TURBO codes and the observed 'error floor' for moderate and high signal-to-noise ratios (SNR's). A semester project, entitled 'The Realization of the Turbo-Coding System,' involved a thorough simulation study of the performance of TURBO codes and verified the results claimed by previous authors. A copy of the final report for this project is included as Appendix A. A diploma project, entitled 'On the Free Distance of Turbo Codes and Related Product Codes,' includes an analysis of TURBO codes and an explanation for their remarkable performance. A copy of the final report for this project is included as Appendix B.
Confidence Intervals for Error Rates Observed in Coded Communications Systems
NASA Astrophysics Data System (ADS)
Hamkins, J.
2015-05-01
We present methods to compute confidence intervals for the codeword error rate (CWER) and bit error rate (BER) of a coded communications link. We review several methods to compute exact and approximate confidence intervals for the CWER, and specifically consider the situation in which the true CWER is so low that only a handful, if any, codeword errors are able to be simulated. In doing so, we answer the question of how long an error-free simulation must be run in order to certify that a given CWER requirement is met with a given level of confidence, and discuss the bias introduced by aborting a simulation after observing the first codeword error. Next, we turn to the lesser studied problem of determining confidence intervals for the BER of coded systems. Since bit errors in systems that use coding or higher-order modulation do not occur independently, blind application of a method that assumes independence leads to inappropriately narrow confidence intervals. We present a new method to compute the confidence interval properly, using the first and second sample moments of the number of bit errors per codeword. This is the first method we know of to compute a confidence interval for the BER of a coded or higher-order modulation system.
Drag drill bit having improved arrangement of cutting elements
Deane, J.D.
1989-07-18
This patent describes a rotary drill bit of the drag type for drilling a bore hole in an earth formation. The generally cylindrical bit body having a fluid passage therein adapted to be connected to a drill string for rotation therewith about a longitudinal axis and to receive drilling fluid from the drillstring; blades on the bit body extending in a generally spiral pattern from adjacent the center of the bit body to the outer periphery thereof and separated from each other by deep groves; each blade having a curved leading side with respect to the direction of rotation extending generally to the outer periphery of the generally cylindrical bit body, a curved trailing side spaced from the leading side, and an outer surface connecting the leading and trailing sides to define the lower surface and crown of the bit body. The surface providing a relatively long length mounting area thereon for cutting elements.
Temperature-compensated 8-bit column driver for AMLCD
NASA Astrophysics Data System (ADS)
Dingwall, Andrew G. F.; Lin, Mark L.
1995-06-01
An all-digital, 5 V input, 50 Mhz bandwidth, 10-bit resolution, 128- column, AMLCD column driver IC has been designed and tested. The 10-bit design can enhance display definition over 6-bit nd 8-bit column drivers. Precision is realized with on-chip, switched-capacitor DACs plus transparently auto-offset-calibrated, opamp outputs. Increased resolution permits multiple 10-bit digital gamma remappings in EPROMs over temperature. Driver IC features include externally programmable number of output column, bi-directional digital data shifting, user- defined row/column/pixel/frame inversion, power management, timing control for daisy-chained column drivers, and digital bit inversion. The architecture uses fewer reference power supplies.
Noise Robust Speech Watermarking with Bit Synchronisation for the Aeronautical Radio
NASA Astrophysics Data System (ADS)
Hofbauer, Konrad; Hering, Horst
Analogue amplitude modulation radios are used for air/ ground voice communication between aircraft pilots and controllers. The identification of the aircraft, so far always transmitted verbally, could be embedded as a watermark in the speech signal and thereby prevent safety-critical misunderstandings. The first part of this paper presents an overview on this watermarking application. The second part proposes a speech watermarking algorithm that embeds data in the linear prediction residual of unvoiced narrowband speech at a rate of up to 2 kbit/s. A bit synchroniser is developed which enables the transmission over analogue channels and which reaches the optimal limit within one to two percentage points in terms of raw bit error rate. Simulations show the robustness of the method for the AWGN channel.
Coexistence of High-Bit-Rate Quantum Key Distribution and Data on Optical Fiber
NASA Astrophysics Data System (ADS)
Patel, K. A.; Dynes, J. F.; Choi, I.; Sharpe, A. W.; Dixon, A. R.; Yuan, Z. L.; Penty, R. V.; Shields, A. J.
2012-10-01
Quantum key distribution (QKD) uniquely allows the distribution of cryptographic keys with security verified by quantum mechanical limits. Both protocol execution and subsequent applications require the assistance of classical data communication channels. While using separate fibers is one option, it is economically more viable if data and quantum signals are simultaneously transmitted through a single fiber. However, noise-photon contamination arising from the intense data signal has severely restricted both the QKD distances and secure key rates. Here, we exploit a novel temporal-filtering effect for noise-photon rejection. This allows high-bit-rate QKD over fibers up to 90 km in length and populated with error-free bidirectional Gb/s data communications. With a high-bit rate and range sufficient for important information infrastructures, such as smart cities and 10-Gbit Ethernet, QKD is a significant step closer toward wide-scale deployment in fiber networks.
New Bits-to-Symbol Mapping for 32 APSK over Nonlinear Satellite Channels
NASA Astrophysics Data System (ADS)
Lee, Jaeyoon; Yoon, Dongweon; Park, Sang Kyu
A 4+12+16 amplitude phase shift keying (APSK) modulation outperforms other 32-APSK modulations such as rectangular or cross 32-quadrature amplitude modulations (QAMs) which have a high peak to average power ratio that causes non-negligible AM/AM and AM/PM distortions when the signal is amplified by a high-power amplifier (HPA). This modulation scheme has therefore been recommended as a standard in the digital video broadcasting-satellite2 (DVB-S2) system. In this letter, we present a new bits-to-symbol mapping with a better bit error rate (BER) for a 4+12+16 APSK signal in a nonlinear satellite channel.
Computational Errors of Mentally Retarded Students.
ERIC Educational Resources Information Center
Janke, Robert W.
1980-01-01
Examined computational errors made by educable mentally retarded students on the arithmetic subtest of the Wide Range Achievement Test. Retarded students had a lower percent of grouping and inappropriate inversion errors and a higher percent of incorrect operation errors than regular students had in Engelhardt's study. (Author)
Effect of image bit depth on target acquisition modeling
NASA Astrophysics Data System (ADS)
Teaney, Brian P.; Reynolds, Joseph P.
2008-04-01
The impact of bit depth on human in the loop recognition and identification performance is of particular importance when considering trade-offs between resolution and band-width of sensor systems. This paper presents the results from two perception studies designed to measure the effects of quantization and finite bit depth on target acquisition performance. The results in this paper allow for the inclusion of limited bit depth and quantization as an additional noise term in NVESD sensor performance models.
Sealed and lubricated rock bit with air protected seal ring
Galle, E.M.
1983-03-01
An earth boring rock bit having a sealed bearing and pressure lubrication system for drilling the earth with air or gas as the circulating medium. An annular groove is formed in the vicinity of the seal and connected to the interior of the bit for cooling the ring and cleaning debris from the area of the ring. The air pressure inside the bit is utilized to bias a movable element in the system to urge lubricant to the bearing.
Cooling system for cooling the bits of a cutting machine
Wrulich, H.; Gekle, S.; Schetina, O.; Zitz, A.
1984-06-26
The invention refers to a system for cooling the bits of a cutting machine and comprising a nozzle for the cooling water to be ejected under pressure, said nozzle being arranged at the area of the bit, the water supply to said nozzle being closable by means of a shutoff valve and the bit being supported on the bit holder for limited axial shifting movement under the action of the cutting pressure against the force of a spring and against the hydraulic pressure of the cooling water and the shutoff valve being coupled with the bit by means of a coupling member such that the shutoff valve is opened on shifting movement of the bit in direction of the cutting pressure. In this system the arrangement is such that the bit (6) has in a manner known per se the shape of a cap and is enclosing a bit shaft (3) adapted to be inserted into the bit holder (1), in that the cap-shaped bit (6) is supported on the shaft (3) for shifting movement in axial direction and in that the shutoff valve (11) and the coupling member (10) are arranged within the bit shaft (3). The coupling member is formed of a push rod (10) acting on the closure member (11) of the valve, said push rod being guided within a central bore (9) of the bit shaft and the closure member (11) closing the valve in opposite direction to the action of the cutting pressure and being moved in open position by the push rod (10) in direction of the acting cutting pressure.
Development and testing of a Mudjet-augmented PDC bit.
Black, Alan; Chahine, Georges; Raymond, David Wayne; Matthews, Oliver; Grossman, James W.; Bertagnolli, Ken (US Synthetic); Vail, Michael
2006-01-01
This report describes a project to develop technology to integrate passively pulsating, cavitating nozzles within Polycrystalline Diamond Compact (PDC) bits for use with conventional rig pressures to improve the rock-cutting process in geothermal formations. The hydraulic horsepower on a conventional drill rig is significantly greater than that delivered to the rock through bit rotation. This project seeks to leverage this hydraulic resource to extend PDC bits to geothermal drilling.
Error diffusion with a more symmetric error distribution
NASA Astrophysics Data System (ADS)
Fan, Zhigang
1994-05-01
In this paper a new error diffusion algorithm is presented that effectively eliminates the `worm' artifacts appearing in the standard methods. The new algorithm processes each scanline of the image in two passes, a forward pass followed by a backward one. This enables the error made at one pixel to be propagated to all the `future' pixels. A much more symmetric error distribution is achieved than that of the standard methods. The frequency response of the noise shaping filter associated with the new algorithm is mirror-symmetric in magnitude.
PDC (polycrystalline diamond compact) bit research at Sandia National Laboratories
Finger, J.T.; Glowka, D.A.
1989-06-01
From the beginning of the geothermal development program, Sandia has performed and supported research into polycrystalline diamond compact (PDC) bits. These bits are attractive because they are intrinsically efficient in their cutting action (shearing, rather than crushing) and they have no moving parts (eliminating the problems of high-temperature lubricants, bearings, and seals.) This report is a summary description of the analytical and experimental work done by Sandia and our contractors. It describes analysis and laboratory tests of individual cutters and complete bits, as well as full-scale field tests of prototype and commercial bits. The report includes a bibliography of documents giving more detailed information on these topics. 26 refs.
New PDC bit design increased penetration rate in slim wells
Gerbaud, L.; Sellami, H.; Lamine, E.; Sagot, A.
1997-07-01
This paper describes slim hole bit design developed at the Paris School of Mines and Security DBS. The design is a compromise between several criteria such as drilling efficiency, uniform wear distribution around the bit face and low level of vibration of the bit, according to the hole diameter and the formation characteristics. Two new bits were manufactured and run successfully in a full scale drilling test bench and in field test in Gabon. The result show improvement of the drilling performances in slimhole application.
Improved seal for geothermal drill bit. Final technical report
Evans, R.F.
1984-07-06
Each of the two field test bits showed some promise though their performances were less than commercially acceptable. The Ohio test bit ran just over 3000 feet where about 4000 is considered a good run but it was noted that a Varel bit of the same type having a standard O ring seal was completely worn out after 8-1/2 hours (1750 feet drilled). The Texas test bit had good seal-bearing life but was the wrong cutting structure type for the formation being drilled and the penetration rate was low.
Quantum bit commitment with cheat sensitive binding and approximate sealing
NASA Astrophysics Data System (ADS)
Li, Yan-Bing; Xu, Sheng-Wei; Huang, Wei; Wan, Zong-Jie
2015-04-01
This paper proposes a cheat-sensitive quantum bit commitment scheme based on single photons, in which Alice commits a bit to Bob. Here, Bob’s probability of success at cheating as obtains the committed bit before the opening phase becomes close to \\frac{1}{2} (just like performing a guess) as the number of single photons used is increased. And if Alice alters her committed bit after the commitment phase, her cheating will be detected with a probability that becomes close to 1 as the number of single photons used is increased. The scheme is easy to realize with present day technology.
The Behavior of Free Riders in Bit Torrent Networks
NASA Astrophysics Data System (ADS)
Zghaibeh, Manaf; Anagnostakis, Kostas G.; Harmantzis, Fotios C.
In this chapter we report on the results of two large-scale measurement studies on BitTorrent. We focus on identifying he strategic behavior of users in response to the incentives that are embedded in the design of BitTorrent. Our results regarding the first study that was performed in year 2005 illustrate a gap between what system designers and researchers expect from users in reaction to the provided incentives, and how users react to them. In particular, we divide users in BitTorrent into four classes based on their interactions with the system. We also provide a measurement of free riders' volume in the BitTorrent environment.
Forward error correction for an atmospheric noise channel
NASA Astrophysics Data System (ADS)
Olson, Katharyn E.; Enge, Per K.
1992-05-01
Two Markov chains are employed to model the memory of the atmospheric noise channel. It derives the transition probabilities for these chains from atmospheric noise error processes that were recorded at 306 kHz. The models are then utilized to estimate the probability of codeword error, and compares these estimates to codeword error rates that are obtained directly from the recorded error processes. These comparisons are made for the Golay code with various bit interleaving depths, and for a Reed-Solomon code with a variety of symbol interleaving depths.
Détection homodyne pour mémoires holographiques à stockage bit à bit
NASA Astrophysics Data System (ADS)
Maire, G.; Pauliat, G.; Roosen, G.
2006-10-01
Les mémoires holographiques à stockage bit à bit sont une alternative intéressante à l'approche holographique conventionnelle par pages de données du fait de leur architecture optique simplifiée. Nous proposons et validons ici une procédure de lecture adaptée à de telles mémoires et basée sur une détection homodyne de l'amplitude diffractée par les hologrammes. Ceci permet d'augmenter la quantité de signal utile détecté et s'avère donc prometteur pour accroître le taux de transfert de données de ces mémoires.
BitPredator: A Discovery Algorithm for BitTorrent Initial Seeders and Peers
Borges, Raymond; Patton, Robert M; Kettani, Houssain; Masalmah, Yahya
2011-01-01
There is a large amount of illegal content being replicated through peer-to-peer (P2P) networks where BitTorrent is dominant; therefore, a framework to profile and police it is needed. The goal of this work is to explore the behavior of initial seeds and highly active peers to develop techniques to correctly identify them. We intend to establish a new methodology and software framework for profiling BitTorrent peers. This involves three steps: crawling torrent indexers for keywords in recently added torrents using Really Simple Syndication protocol (RSS), querying torrent trackers for peer list data and verifying Internet Protocol (IP) addresses from peer lists. We verify IPs using active monitoring methods. Peer behavior is evaluated and modeled using bitfield message responses. We also design a tool to profile worldwide file distribution by mapping IP-to-geolocation and linking to WHOIS server information in Google Earth.
[Diagnostic Errors in Medicine].
Buser, Claudia; Bankova, Andriyana
2015-12-01
The recognition of diagnostic errors in everyday practice can help improve patient safety. The most common diagnostic errors are the cognitive errors, followed by system-related errors and no fault errors. The cognitive errors often result from mental shortcuts, known as heuristics. The rate of cognitive errors can be reduced by a better understanding of heuristics and the use of checklists. The autopsy as a retrospective quality assessment of clinical diagnosis has a crucial role in learning from diagnostic errors. Diagnostic errors occur more often in primary care in comparison to hospital settings. On the other hand, the inpatient errors are more severe than the outpatient errors. PMID:26649954
Experimental test of Landauer’s principle in single-bit operations on nanomagnetic memory bits
Hong, Jeongmin; Lambson, Brian; Dhuey, Scott; Bokor, Jeffrey
2016-01-01
Minimizing energy dissipation has emerged as the key challenge in continuing to scale the performance of digital computers. The question of whether there exists a fundamental lower limit to the energy required for digital operations is therefore of great interest. A well-known theoretical result put forward by Landauer states that any irreversible single-bit operation on a physical memory element in contact with a heat bath at a temperature T requires at least kBT ln(2) of heat be dissipated from the memory into the environment, where kB is the Boltzmann constant. We report an experimental investigation of the intrinsic energy loss of an adiabatic single-bit reset operation using nanoscale magnetic memory bits, by far the most ubiquitous digital storage technology in use today. Through sensitive, high-precision magnetometry measurements, we observed that the amount of dissipated energy in this process is consistent (within 2 SDs of experimental uncertainty) with the Landauer limit. This result reinforces the connection between “information thermodynamics” and physical systems and also provides a foundation for the development of practical information processing technologies that approach the fundamental limit of energy dissipation. The significance of the result includes insightful direction for future development of information technology. PMID:26998519
Experimental test of Landauer's principle in single-bit operations on nanomagnetic memory bits.
Hong, Jeongmin; Lambson, Brian; Dhuey, Scott; Bokor, Jeffrey
2016-03-01
Minimizing energy dissipation has emerged as the key challenge in continuing to scale the performance of digital computers. The question of whether there exists a fundamental lower limit to the energy required for digital operations is therefore of great interest. A well-known theoretical result put forward by Landauer states that any irreversible single-bit operation on a physical memory element in contact with a heat bath at a temperature T requires at least k B T ln(2) of heat be dissipated from the memory into the environment, where k B is the Boltzmann constant. We report an experimental investigation of the intrinsic energy loss of an adiabatic single-bit reset operation using nanoscale magnetic memory bits, by far the most ubiquitous digital storage technology in use today. Through sensitive, high-precision magnetometry measurements, we observed that the amount of dissipated energy in this process is consistent (within 2 SDs of experimental uncertainty) with the Landauer limit. This result reinforces the connection between "information thermodynamics" and physical systems and also provides a foundation for the development of practical information processing technologies that approach the fundamental limit of energy dissipation. The significance of the result includes insightful direction for future development of information technology. PMID:26998519
Microdensitometer errors: Their effect on photometric data reduction
NASA Technical Reports Server (NTRS)
Bozyan, E. P.; Opal, C. B.
1984-01-01
The performance of densitometers used for photometric data reduction of high dynamic range electrographic plate material is analyzed. Densitometer repeatability is tested by comparing two scans of one plate. Internal densitometer errors are examined by constructing histograms of digitized densities and finding inoperative bits and differential nonlinearity in the analog to digital converter. Such problems appear common to the four densitometers used in this investigation and introduce systematic algorithm dependent errors in the results. Strategies to improve densitometer performance are suggested.
The undetected error probability for shortened hamming codes
NASA Technical Reports Server (NTRS)
Costello, D. J., Jr.; Lin, S.
1984-01-01
Hamming or shortened Hamming codes are widely used for error detection in data communications. For example, the CCITT (International Telegraph and Telephone Consultative Committee) recommendation X.25 for packet-switched data networks adopts a distance-4 cyclic Hamming code with 16 parity-check bits for error detection. The natural length of this code is n = 2(15)-1 = 32,767. In practice the length of a data packet is no more than a few thousand bits which is much shorter than the natural length of the code. Consequently, a shortened version of thecode is used. Often the length of a data packet varies, say from a few hundred bits to a few thousand bits, hence the code must be shortened by various degrees. Shortening affects the performance of the code. The error-detection performance of shortened Hamming codes, particularly the codes obtained from the distance-4 Hamming codes adopted by CCITT recommendation X.25, is investigated. A method for computing the probability of an undetected error is presented.
Injecting Errors for Testing Built-In Test Software
NASA Technical Reports Server (NTRS)
Gender, Thomas K.; Chow, James
2010-01-01
Two algorithms have been conceived to enable automated, thorough testing of Built-in test (BIT) software. The first algorithm applies to BIT routines that define pass/fail criteria based on values of data read from such hardware devices as memories, input ports, or registers. This algorithm simulates effects of errors in a device under test by (1) intercepting data from the device and (2) performing AND operations between the data and the data mask specific to the device. This operation yields values not expected by the BIT routine. This algorithm entails very small, permanent instrumentation of the software under test (SUT) for performing the AND operations. The second algorithm applies to BIT programs that provide services to users application programs via commands or callable interfaces and requires a capability for test-driver software to read and write the memory used in execution of the SUT. This algorithm identifies all SUT code execution addresses where errors are to be injected, then temporarily replaces the code at those addresses with small test code sequences to inject latent severe errors, then determines whether, as desired, the SUT detects the errors and recovers
Trellis coded modulation for 4800-9600 bits/s transmission over a fading mobile satellite channel
NASA Technical Reports Server (NTRS)
Divsalar, Dariush; Simon, Marvin K.
1987-01-01
The combination of trellis coding and multiple phase-shift-keyed (MPSK) signaling with the addition of asymmetry to the signal set is discussed with regard to its suitability as a modulation/coding scheme for the fading mobile satellite channel. For MPSK, introducing nonuniformity (asymmetry) into the spacing between signal points in the constellation buys a further improvement in performance over that achievable with trellis coded symmetric MPSK, all this without increasing average or peak power, or changing the bandwidth constraints imposed on the system. Whereas previous contributions have considered the performance of trellis coded modulation transmitted over an additive white Gaussian noise (AWGN) channel, the emphasis in the paper is on the performance of trellis coded MPSK in the fading environment. The results will be obtained by using a combination of analysis and simulation. It will be assumed that the effect of the fading on the phase of the received signal is fully compensated for either by tracking it with some form of phase-locked loop or with pilot tone calibration techniques. Thus, results will reflect only the degradation due to the effect of the fading on the amplitude of the received signal. Also, we shall consider only the case where interleaving/deinterleaving is employed to further combat the fading. This allows for considerable simplification of the analysis and is of great practical interest. Finally, the impact of the availability of channel state information on average bit error probability performance is assessed.
Optimized entanglement-assisted quantum error correction
Taghavi, Soraya; Brun, Todd A.; Lidar, Daniel A.
2010-10-15
Using convex optimization, we propose entanglement-assisted quantum error-correction procedures that are optimized for given noise channels. We demonstrate through numerical examples that such an optimized error-correction method achieves higher channel fidelities than existing methods. This improved performance, which leads to perfect error correction for a larger class of error channels, is interpreted in at least some cases by quantum teleportation, but for general channels this interpretation does not hold.
Occurence probability of multiple bit errors in digital line systems with MMS43 block codes
NASA Astrophysics Data System (ADS)
Morgenstern, G.
1981-02-01
Probabilities were calculated for the transmission of a signal which is a pure random sequence. The calculation is indicated to be also applicable to other block codes and to other scramblers and descramblers. Results with and without scramblers are compiled in tables, the application of which is illustrated by examples.
Error analysis of real time and post processed or bit determination of GFO using GPS tracking
NASA Technical Reports Server (NTRS)
Schreiner, William S.
1991-01-01
The goal of the Navy's GEOSAT Follow-On (GFO) mission is to map the topography of the world's oceans in both real time (operational) and post processed modes. Currently, the best candidate for supplying the required orbit accuracy is the Global Positioning System (GPS). The purpose of this fellowship was to determine the expected orbit accuracy for GFO in both the real time and post-processed modes when using GPS tracking. This report presents the work completed through the ending date of the fellowship.
Template-Assisted Direct Growth of 1 Td/in(2) Bit Patterned Media.
Yang, En; Liu, Zuwei; Arora, Hitesh; Wu, Tsai-Wei; Ayanoor-Vitikkate, Vipin; Spoddig, Detlef; Bedau, Daniel; Grobis, Michael; Gurney, Bruce A; Albrecht, Thomas R; Terris, Bruce
2016-07-13
We present a method for growing bit patterned magnetic recording media using directed growth of sputtered granular perpendicular magnetic recording media. The grain nucleation is templated using an epitaxial seed layer, which contains Pt pillars separated by amorphous metal oxide. The scheme enables the creation of both templated data and servo regions suitable for high density hard disk drive operation. We illustrate the importance of using a process that is both topographically and chemically driven to achieve high quality media. PMID:27295317
A Contourlet-Based Embedded Image Coding Scheme on Low Bit-Rate
NASA Astrophysics Data System (ADS)
Song, Haohao; Yu, Songyu
Contourlet transform (CT) is a new image representation method, which can efficiently represent contours and textures in images. However, CT is a kind of overcomplete transform with a redundancy factor of 4/3. If it is applied to image compression straightforwardly, the encoding bit-rate may increase to meet a given distortion. This fact baffles the coding community to develop CT-based image compression techniques with satisfactory performance. In this paper, we analyze the distribution of significant contourlet coefficients in different subbands and propose a new contourlet-based embedded image coding (CEIC) scheme on low bit-rate. The well-known wavelet-based embedded image coding (WEIC) algorithms such as EZW, SPIHT and SPECK can be easily integrated into the proposed scheme by constructing a virtual low frequency subband, modifying the coding framework of WEIC algorithms according to the structure of contourlet coefficients, and adopting a high-efficiency significant coefficient scanning scheme for CEIC scheme. The proposed CEIC scheme can provide an embedded bit-stream, which is desirable in heterogeneous networks. Our experiments demonstrate that the proposed scheme can achieve the better compression performance on low bit-rate. Furthermore, thanks to the contourlet adopted in the proposed scheme, more contours and textures in the coded images are preserved to ensure the superior subjective quality.
Design and implementation of low power clock gated 64-bit ALU on ultra scale FPGA
NASA Astrophysics Data System (ADS)
Gupta, Ashutosh; Murgai, Shruti; Gulati, Anmol; Kumar, Pradeep
2016-03-01
64-bit energy efficient Arithmetic and Logic Unit using negative latch based clock gating technique is designed in this paper. The 64-bit ALU is designed using multiplexer based full adder cell. We have designed a 64-bit ALU with a gated clock. We have used negative latch based circuit for generating gated clock. This gated clock is used to control the multiplexer based 64-bit ALU. The circuit has been synthesized on kintex FPGA through Xilinx ISE Design Suite 14.7 using 28 nm technology in Verilog HDL. The circuit has been simulated on Modelsim 10.3c. The design is verified using System Verilog on QuestaSim in UVM environment. We have achieved 74.07%, 92. 93% and 95.53% reduction in total clock power, 89.73%, 91.35% and 92.85% reduction in I/Os power, 67.14%, 62.84% and 74.34% reduction in dynamic power and 25.47%, 29.05% and 46.13% reduction in total supply power at 20 MHz, 200 MHz and 2 GHz frequency respectively. The power has been calculated using XPower Analyzer tool of Xilinx ISE Design Suite 14.3.
Kim, Min-Kyu; Hong, Seong-Kwan; Kwon, Oh-Kyong
2015-01-01
This paper presents a fast multiple sampling method for low-noise CMOS image sensor (CIS) applications with column-parallel successive approximation register analog-to-digital converters (SAR ADCs). The 12-bit SAR ADC using the proposed multiple sampling method decreases the A/D conversion time by repeatedly converting a pixel output to 4-bit after the first 12-bit A/D conversion, reducing noise of the CIS by one over the square root of the number of samplings. The area of the 12-bit SAR ADC is reduced by using a 10-bit capacitor digital-to-analog converter (DAC) with four scaled reference voltages. In addition, a simple up/down counter-based digital processing logic is proposed to perform complex calculations for multiple sampling and digital correlated double sampling. To verify the proposed multiple sampling method, a 256 × 128 pixel array CIS with 12-bit SAR ADCs was fabricated using 0.18 μm CMOS process. The measurement results shows that the proposed multiple sampling method reduces each A/D conversion time from 1.2 μs to 0.45 μs and random noise from 848.3 μV to 270.4 μV, achieving a dynamic range of 68.1 dB and an SNR of 39.2 dB. PMID:26712765
Kim, Min-Kyu; Hong, Seong-Kwan; Kwon, Oh-Kyong
2015-01-01
This paper presents a fast multiple sampling method for low-noise CMOS image sensor (CIS) applications with column-parallel successive approximation register analog-to-digital converters (SAR ADCs). The 12-bit SAR ADC using the proposed multiple sampling method decreases the A/D conversion time by repeatedly converting a pixel output to 4-bit after the first 12-bit A/D conversion, reducing noise of the CIS by one over the square root of the number of samplings. The area of the 12-bit SAR ADC is reduced by using a 10-bit capacitor digital-to-analog converter (DAC) with four scaled reference voltages. In addition, a simple up/down counter-based digital processing logic is proposed to perform complex calculations for multiple sampling and digital correlated double sampling. To verify the proposed multiple sampling method, a 256 × 128 pixel array CIS with 12-bit SAR ADCs was fabricated using 0.18 μm CMOS process. The measurement results shows that the proposed multiple sampling method reduces each A/D conversion time from 1.2 μs to 0.45 μs and random noise from 848.3 μV to 270.4 μV, achieving a dynamic range of 68.1 dB and an SNR of 39.2 dB. PMID:26712765
Error Correction Coding for Reliable Communication in the Presence of Extreme Noise.
NASA Astrophysics Data System (ADS)
Chao, Chi-Chao
This thesis is a study of error-correcting codes for reliable communication in the presence of extreme noise. We consider very noisy channels, which occur in practice by pushing ordinary channels to their physical limits. Both block codes and convolutional codes are examined. We show that the family of triply orthogonal codes, defined and studied in this thesis, or orthogonal codes can be used to achieve channel capacity for certain classes of very noisy discrete memoryless channels. The performance of binary block codes on the unquantized additive white Gaussian noise channel at very low signal-to-noise ratios is studied. Expressions are derived for the decoder block error as well as bit error probabilities and the asymptotic coding gain near the point where the signal energy is zero. The average distance spectrum for the ensemble of time-varying convolutional codes is computed, and the result gives a surprisingly accurate prediction of the growth rate of the number of fundamental paths at large distance for fixed codes. A Gilbert-like free distance lower bound is also given. Finally, a Markov chain model is developed to approximate burst error statistics of Viterbi decoding. The model is validated through computer simulations and is compared with the previously proposed geometric model.
Document Retrieval Using a Serial Bit String Search.
ERIC Educational Resources Information Center
Harding, Alan F.; And Others
1983-01-01
The experimental best match information retrieval system described is based on serial file organization. Documents and queries are characterized by fixed length bit strings (generated by automatic and manual methods) and character-by-character term match is preceeded by bit string search to eliminate documents which cannot satisfy query.…
TriBITS (Tribal Build, Integrate, and Test System)
2013-05-16
TriBITS is a configuration, build, test, and reporting system that uses the Kitware open-source CMake/CTest/CDash system. TriBITS contains a number of custom CMake/CTest scripts and python scripts that extend the functionality of the out-of-the-box CMake/CTest/CDash system.
Drill bit stud and method of manufacture
Hake, L.W.; Huff, C.F.; Miller, J.W.
1984-10-23
A polycrystalline diamond compact is a polycrystalline diamond wafer attached to a tungsten carbide substrate forming a disc. In this form, it is attached to a stud which is attached within a drill bit. The compact is attached to the stud with the aid of a positioning ring. When the stud is made of impact resistant material, a full pedestal may be formed on the stud to facilitate the use of the positioning ring. When the stud is made of brittle material, the positioning ring is attached to the flat face of the stud without a pedestal. The ring is positioned on a stud and the disc inserted in the ring so that the disc is positioned against the bonding surface. The disc remains in position against the bonding surface during the handling before and during the bonding process. As a second embodiment, the polycrystalline diamond compact is smaller than the disc itself and the remainder of the disc is formed of metal having the same thickness as the polycrystalline diamond compact or its tungsten carbide substrate. The shape of the smaller polycrystalline diamond compact may be semicircular, circular, polygon shaped, (i.e., triangular, square, etc.) or other geometric figures.
Single Abrikosov vortices as quantized information bits
Golod, T.; Iovan, A.; Krasnov, V. M.
2015-01-01
Superconducting digital devices can be advantageously used in future supercomputers because they can greatly reduce the dissipation power and increase the speed of operation. Non-volatile quantized states are ideal for the realization of classical Boolean logics. A quantized Abrikosov vortex represents the most compact magnetic object in superconductors, which can be utilized for creation of high-density digital cryoelectronics. In this work we provide a proof of concept for Abrikosov-vortex-based random access memory cell, in which a single vortex is used as an information bit. We demonstrate high-endurance write operation and two different ways of read-out using a spin valve or a Josephson junction. These memory cells are characterized by an infinite magnetoresistance between 0 and 1 states, a short access time, a scalability to nm sizes and an extremely low write energy. Non-volatility and perfect reproducibility are inherent for such a device due to the quantized nature of the vortex. PMID:26456592
Continuous chain bit with downhole cycling capability
Ritter, Don F.; St. Clair, Jack A.; Togami, Henry K.
1983-01-01
A continuous chain bit for hard rock drilling is capable of downhole cycling. A drill head assembly moves axially relative to a support body while the chain on the head assembly is held in position so that the bodily movement of the chain cycles the chain to present new composite links for drilling. A pair of spring fingers on opposite sides of the chain hold the chain against movement. The chain is held in tension by a spring-biased tensioning bar. A head at the working end of the chain supports the working links. The chain is centered by a reversing pawl and piston actuated by the pressure of the drilling mud. Detent pins lock the head assembly with respect to the support body and are also operated by the drilling mud pressure. A restricted nozzle with a divergent outlet sprays drilling mud into the cavity to remove debris. Indication of the centered position of the chain is provided by noting a low pressure reading indicating proper alignment of drilling mud slots on the links with the corresponding feed branches.
Gravitons, inflatons, twisted bits: A noncommutative bestiary
NASA Astrophysics Data System (ADS)
Pearson, John
In this work, we examine ideas connected with the noncommutativity of spacetime and its realizations in string theory. Motivated by Matrix Theory and the AdS-CFT correspondence, we propose a survey of selected noncommutative objects, assessing their implications for inflation, gauge theory duals, and solvable backgrounds. Our initial pair of examples, related to the Myers effect, incorporate elements of so-called "giant graviton" behavior. In the first, the formation of an extended, supersymmetry-restoring domain wall from point-brane sources in a flux background is related to a nonperturbative process of brane-flux annihilation. In the second, we reexamine these phenomena from a cosmological vantage, investigating the prospect of slow-roll inflation in the noncommutative configuration space of multiple d-branes. For our third and final example, we turn to the solvable pp-wave background, outlining a combinatorial, permutation-based approach to string physics which interpolates between gauge theory and worldsheet methods. This "string bit" language will allow us to find exact agreement between Yang-Mills theory in the large R-charge sector and string field theory on the light cone, resolving some previous discrepancies in the literature.
Fixed-point error analysis of Winograd Fourier transform algorithms
NASA Technical Reports Server (NTRS)
Patterson, R. W.; Mcclellan, J. H.
1978-01-01
The quantization error introduced by the Winograd Fourier transform algorithm (WFTA) when implemented in fixed-point arithmetic is studied and compared with that of the fast Fourier transform (FFT). The effect of ordering the computational modules and the relative contributions of data quantization error and coefficient quantization error are determined. In addition, the quantization error introduced by the Good-Winograd (GW) algorithm, which uses Good's prime-factor decomposition for the discrete Fourier transform (DFT) together with Winograd's short length DFT algorithms, is studied. Error introduced by the WFTA is, in all cases, worse than that of the FFT. In general, the WFTA requires one or two more bits for data representation to give an error similar to that of the FFT. Error introduced by the GW algorithm is approximately the same as that of the FFT.
Error-resilient method for robust video transmissions
NASA Astrophysics Data System (ADS)
Choi, Dong-Hwan; Lim, Tae-Gyun; Lee, Sang-Hak; Hwang, Chan-Sik
2003-06-01
In this paper we address the problems of video transmission in error prone environments. A novel error-resilient method is proposed that uses a data embedding scheme for header parameters in video coding standards, such as MPEG-2 and H.263. In case of requiring taking the loss of data information into account except for header errors, the video decoder hides visual degradation as well as possible, employing an error concealment method using an affine transform. Header information is very important because syntax elements, tables, and decoding processes all depend on the values of the header information. Therefore, transmission errors in header information can result in serious visual degradation of the output video and also cause an abnormal decoding process. In the proposed method, the header parameters are embedded into the least significant bits (LSB) of the quantized DCT coefficients. Then, when errors occur in the header field of the compressed bitstream, the decoder can accurately recover the corrupted header parameters if the embedded information is extracted correctly. The error concealment technique employed in this paper uses motion estimation considering actual motions, such as rotation, magnification, reduction, and parallel motion, in moving pictures. Experimental results show that the proposed error-resilient method can effectively reconstruct the original video sequence without any additional bits or modifications to the video coding standard and the error concealment method can produce a higher PSNR value and better subjective video quality, estimating the motion of lost data more accurately.
Variable length three-cone rock bit nozzles
Shoemaker, K.S.
1987-05-19
A three-cone sealed bearing rock bit is described of the type that utilizes drilling fluid during operation of the rock bit in an earth formation comprising: a rock bit body having a first pin end and a second cutting end. The cutting end consists of rotary cones mounted to journals that are cantilevered radially inwardly from legs extending from the rock bit body; a fluid chamber formed by the body. The fluid chamber is opened at the first pin end of the body; and at least three variable length nozzle bodies positioned about 120/sup 0/ one from the other, extend from a dome portion formed at a base of the bit body toward a bottom of a borehole in the earth formation. Each of the nozzle bodies communicates with the fluid chamber in the body and extends a different length from the dome portion.
Evolution of a Hybrid Roller Cone/PDC core bit
Pettitt, R.; Laney, R.; George, D.; Clemens, G.
1980-01-01
The development of the hot dry rock (HDR) geothermal resource, as presently being accomplished by the Los Alamos Scientific Laboratory (LASL), requires that sufficient quantities of good quality core be obtained at a reasonable cost. The use of roller cone core bits, with tungsten carbide inserts, was initiated by the Deep Sea Drilling Program. These bits were modified for continental drilling in deep, hot, granitic rock for the LASL HDR Geothermal Site at Fenton Hill, New Mexico in 1974. After the advent of monocrystalline diamond Stratapax pads, a prototype hybrid roller cone/Stratapax core bit was fabricated by Smith Tool, and tested at Fenton Hill in 1978. During the drilling for a deeper HDR reservoir system in 1979 and 1980, six of the latest generation of these bits, now called Hybrid Roller Cone/Polycrystalline Diamond Cutter (PDC) core bits, were successfully used in granitic rock at depths below 11,000 ft.
Montgomery Multiplication with Twice the Bit-Length of Multipliers
NASA Astrophysics Data System (ADS)
Yoshino, Masayuki; Okeya, Katsuyuki; Vuillaume, Camille
We present a novel approach for computing 2n-bit Montgomery multiplications with n-bit hardware Montgomery multipliers. Smartcards are usually equipped with such hardware Montgomery multipliers; however, due to progresses in factoring algorithms, the recommended bit length of public-key schemes such as RSA is steadily increasing, making the hardware quickly obsolete. Thanks to our double-size technique, one can re-use the existing hardware while keeping pace with the latest security requirements. Unlike the other double-size techniques which rely on classical n-bit modular multipliers, our idea is tailored to take advantage of n-bit Montgomery multipliers. Thus, our technique increases the perenniality of existing products without compromises in terms of security.
Uniqueness: skews bit occurrence frequencies in randomly generated fingerprint libraries.
Chen, Nelson G
2016-08-01
Requiring that randomly generated chemical fingerprint libraries have unique fingerprints such that no two fingerprints are identical causes a systematic skew in bit occurrence frequencies, the proportion at which specified bits are set. Observed frequencies (O) at which each bit is set within the resulting libraries systematically differ from frequencies at which bits are set at fingerprint generation (E). Observed frequencies systematically skew toward 0.5, with the effect being more pronounced as library size approaches the compound space, which is the total number of unique possible fingerprints given the number of bit positions each fingerprint contains. The effect is quantified for varying library sizes as a fraction of the overall compound space, and for changes in the specified frequency E. The cause and implications for this systematic skew are subsequently discussed. When generating random libraries of chemical fingerprints, the imposition of a uniqueness requirement should either be avoided or taken into account. PMID:27230477
The application of low-bit-rate encoding techniques to digital satellite systems
NASA Astrophysics Data System (ADS)
Rowbotham, T. R.; Niwa, K.
This paper describes the INTELSAT-funded development on low-bit-rate voice encoding techniques. Adaptive Differential Pulse Code Modulation (ADPCM), Nearly Instantaneous Companding (NIC) and Continuously Variable Slope Delta Modulation (CVSD). Subjective and objective evaluation results, with and without transmission errors are presented, primarily for 32 kbit/s per voice channel. A part of the paper is devoted to the interfacing of ADPCM, NIC and CVSD with terrestrial ISDM and satellite networks, the frame structure and how signalling can be accommodated, and the compatibility with other voice-associated digital processors such as DSI and Echo Cancellers.
NASA Technical Reports Server (NTRS)
Blucker, T. J.; Ferry, W. W.
1971-01-01
An error model is described for the Apollo 15 sun compass, a contingency navigational device. Field test data are presented along with significant results of the test. The errors reported include a random error resulting from tilt in leveling the sun compass, a random error because of observer sighting inaccuracies, a bias error because of mean tilt in compass leveling, a bias error in the sun compass itself, and a bias error because the device is leveled to the local terrain slope.
Superdense coding interleaved with forward error correction
Humble, Travis S.; Sadlier, Ronald J.
2016-05-12
Superdense coding promises increased classical capacity and communication security but this advantage may be undermined by noise in the quantum channel. We present a numerical study of how forward error correction (FEC) applied to the encoded classical message can be used to mitigate against quantum channel noise. By studying the bit error rate under different FEC codes, we identify the unique role that burst errors play in superdense coding, and we show how these can be mitigated against by interleaving the FEC codewords prior to transmission. As a result, we conclude that classical FEC with interleaving is a useful methodmore » to improve the performance in near-term demonstrations of superdense coding.« less
A 14-bit 40-MHz analog front end for CCD application
NASA Astrophysics Data System (ADS)
Jingyu, Wang; Zhangming, Zhu; Shubin, Liu
2016-06-01
A 14-bit, 40-MHz analog front end (AFE) for CCD scanners is analyzed and designed. The proposed system incorporates a digitally controlled wideband variable gain amplifier (VGA) with nearly 42 dB gain range, a correlated double sampler (CDS) with programmable gain functionality, a 14-bit analog-to-digital converter and a programmable timing core. To achieve the maximum dynamic range, the VGA proposed here can linearly amplify the input signal in a gain range from ‑1.08 to 41.06 dB in 6.02 dB step with a constant bandwidth. A novel CDS takes image information out of noise, and further amplifies the signal accurately in a gain range from 0 to 18 dB in 0.035 dB step. A 14-bit ADC is adopted to quantify the analog signal with optimization in power and linearity. An internal timing core can provide flexible timing for CCD arrays, CDS and ADC. The proposed AFE was fabricated in SMIC 0.18 μm CMOS process. The whole circuit occupied an active area of 2.8 × 4.8 mm2 and consumed 360 mW. When the frequency of input signal is 6.069 MHz, and the sampling frequency is 40 MHz, the signal to noise and distortion (SNDR) is 70.3 dB, the effective number of bits is 11.39 bit. Project supported by the National Natural Science Foundation of China (Nos. 61234002, 61322405, 61306044, 61376033), the National High-Tech Program of China (No. 2013AA014103), and the Opening Project of Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory (No. ZHD201302).
3D bit-oriented optical storage in photopolymers
NASA Astrophysics Data System (ADS)
Orlic, Susanna; Ulm, Steffen; Eichler, Hans Joachim
2001-01-01
The bit-oriented data storage of conventional optical disks may be expanded into the third dimension by using microscopic reflection gratings instead of pits. Microgratings are holographically induced in a photopolymer layer. The Bragg selectivity of holographic volume gratings makes the application of multiplexing methods possible. High storage density may be achieved by combining wavelength multiplexing and multilayer storage. Wavelength multiplexing is realized by recording several gratings overlapping with write beams of different wavelengths. All gratings are recorded simultaneously in the same volume element. By translating a photopolymer sample perpendicularly to the laser beam axis during exposure, stripe-shaped microgratings are induced dynamically with constant linear velocity. The length of a grating is defined by the exposure time. Stripe-shaped gratings are required to realize an areal structure of recorded data similar to the pit-land structure of conventional disks that allows us to overtake the progress made in proceeding CD/DVD technology. Experimental results have been obtained for writing and reading of microholograms in different photopolymer materials including DuPont holographic recording films and CROP photopolymers from Polaroid.
Robust characterization of leakage errors
NASA Astrophysics Data System (ADS)
Wallman, Joel J.; Barnhill, Marie; Emerson, Joseph
2016-04-01
Leakage errors arise when the quantum state leaks out of some subspace of interest, for example, the two-level subspace of a multi-level system defining a computational ‘qubit’, the logical code space of a quantum error-correcting code, or a decoherence-free subspace. Leakage errors pose a distinct challenge to quantum control relative to the more well-studied decoherence errors and can be a limiting factor to achieving fault-tolerant quantum computation. Here we present a scalable and robust randomized benchmarking protocol for quickly estimating the leakage rate due to an arbitrary Markovian noise process on a larger system. We illustrate the reliability of the protocol through numerical simulations.
Decision Fusion with Channel Errors in Distributed Decode-Then-Fuse Sensor Networks
Yan, Yongsheng; Wang, Haiyan; Shen, Xiaohong; Zhong, Xionghu
2015-01-01
Decision fusion for distributed detection in sensor networks under non-ideal channels is investigated in this paper. Usually, the local decisions are transmitted to the fusion center (FC) and decoded, and a fusion rule is then applied to achieve a global decision. We propose an optimal likelihood ratio test (LRT)-based fusion rule to take the uncertainty of the decoded binary data due to modulation, reception mode and communication channel into account. The average bit error rate (BER) is employed to characterize such an uncertainty. Further, the detection performance is analyzed under both non-identical and identical local detection performance indices. In addition, the performance of the proposed method is compared with the existing optimal and suboptimal LRT fusion rules. The results show that the proposed fusion rule is more robust compared to these existing ones. PMID:26251908
Error-free DWDM transmission and crosstalk analysis for a silicon photonics transmitter.
Seyedi, M Ashkan; Chen, Chin-Hui; Fiorentino, Marco; Beausoleil, Ray
2015-12-28
Individual channels of a five-channel microring silicon photonics transmitter are used for bit error ratio analysis and demonstrate error-free transmission at 10Gb/s. Two channels of the same transmitter are concurrently modulated using an 80GHz channel spacing comb laser and demonstrate open eye diagrams at 10Gb/s and 12.5Gb/s. Finally, concurrent modulation with tunable lasers is done to quantify optical power penalty for link bit error ratio versus channel spacing from +100GHz to -100GHz. When using a comb laser for concurrent modulation, no direct power penalty is observed for an 80GHz channel separation. PMID:26831964
Remediating Common Math Errors.
ERIC Educational Resources Information Center
Wagner, Rudolph F.
1981-01-01
Explanations and remediation suggestions for five types of mathematics errors due either to perceptual or cognitive difficulties are given. Error types include directionality problems, mirror writing, visually misperceived signs, diagnosed directionality problems, and mixed process errors. (CL)
Reducing Bits in Electrodeposition Process of Commercial Vehicle - A Case Study
NASA Astrophysics Data System (ADS)
Rahim, Nabiilah Ab; Hamedon, Zamzuri; Mohd Turan, Faiz; Iskandar, Ismed
2016-02-01
Painting process is critical in commercial vehicle manufacturing process for protection and decorative. The good quality on painted body is important to reduce repair cost and achieve customer satisfaction. In order to achieve the good quality, it is important to reduce the defect at the first process in painting process which is electrodeposition process. The Pareto graph and cause and effect diagram in the seven QC tools is utilized to reduce the electrodeposition defects. The main defects in the electrodeposition process in this case study are the bits. The 55% of the bits are iron filings. The iron filings which come from the metal assembly process at the body shop are minimised by controlling the spot welding parameter, defect control and standard body cleaning process. However the iron filings are still remained on the body and carry over to the paint shop. The remained iron filings on the body are settled inside the dipping tank and removed by filtration system and magnetic separation. The implementation of filtration system and magnetic separation improved 27% of bits and reduced 42% of sanding man hour with a total saving of RM38.00 per unit.
Cooperative MIMO Communication at Wireless Sensor Network: An Error Correcting Code Approach
Islam, Mohammad Rakibul; Han, Young Shin
2011-01-01
Cooperative communication in wireless sensor network (WSN) explores the energy efficient wireless communication schemes between multiple sensors and data gathering node (DGN) by exploiting multiple input multiple output (MIMO) and multiple input single output (MISO) configurations. In this paper, an energy efficient cooperative MIMO (C-MIMO) technique is proposed where low density parity check (LDPC) code is used as an error correcting code. The rate of LDPC code is varied by varying the length of message and parity bits. Simulation results show that the cooperative communication scheme outperforms SISO scheme in the presence of LDPC code. LDPC codes with different code rates are compared using bit error rate (BER) analysis. BER is also analyzed under different Nakagami fading scenario. Energy efficiencies are compared for different targeted probability of bit error pb. It is observed that C-MIMO performs more efficiently when the targeted pb is smaller. Also the lower encoding rate for LDPC code offers better error characteristics. PMID:22163732
Earth boring bit with pressure compensating rigid face seal
Burr, B. H.
1985-05-14
An earth boring bit having a cantilevered bearing shaft and a compensator system to equalize the pressure of the lubricant with the hydrostatic pressure of the drilling fluid surrounding the bit. A rigid face seal assembly, positioned between the cutter and bearing shaft of the bit, moves axially in response to, and to compensate for, dynamic pressure changes in the lubricant adjacent the seal. This is accomplished by the positioning and sizing of resilient energizer rings in relationship to the geometries of the mating grooves between the cutter and shaft and the rigid sealing rings of the face seal assembly.
Impact of bit performance on geothermal-well cost
Lin, Y.T.
1981-01-01
The impacts of technological improvements in drill bits on geothermal well costs are evaluated using a compilation of well costs associated with conventional drilling technology. The compilation centers around well models that have been constructed for the major US geothermal areas. Parametric analyses showing the relative importance of the bit performance parameters in well cost reduction and the results of analyses of specific new bit technologies are presented. These results have been used to evaluate the benefits of new technologies and to direct their development.
Fitness Probability Distribution of Bit-Flip Mutation.
Chicano, Francisco; Sutton, Andrew M; Whitley, L Darrell; Alba, Enrique
2015-01-01
Bit-flip mutation is a common mutation operator for evolutionary algorithms applied to optimize functions over binary strings. In this paper, we develop results from the theory of landscapes and Krawtchouk polynomials to exactly compute the probability distribution of fitness values of a binary string undergoing uniform bit-flip mutation. We prove that this probability distribution can be expressed as a polynomial in p, the probability of flipping each bit. We analyze these polynomials and provide closed-form expressions for an easy linear problem (Onemax), and an NP-hard problem, MAX-SAT. We also discuss a connection of the results with runtime analysis. PMID:24885680
Compressing molecular dynamics trajectories: Breaking the one-bit-per-sample barrier.
Huwald, Jan; Richter, Stephan; Ibrahim, Bashar; Dittrich, Peter
2016-07-01
Molecular dynamics simulations yield large amounts of trajectory data. For their durable storage and accessibility an efficient compression algorithm is paramount. State of the art domain-specific algorithms combine quantization, Huffman encoding and occasionally domain knowledge. We propose the high resolution trajectory compression scheme (HRTC) that relies on piecewise linear functions to approximate quantized trajectories. By splitting the error budget between quantization and approximation, our approach beats the current state of the art by several orders of magnitude given the same error tolerance. It allows storing samples at far less than one bit per sample. It is simple and fast enough to be integrated into the inner simulation loop, store every time step, and become the primary representation of trajectory data. © 2016 Wiley Periodicals, Inc. PMID:27191931
Huang, H K; Lo, S C; Ho, B K; Lou, S L
1987-05-01
Some error-free and irreversible two-dimensional direct-cosine-transform (2D-DCT) coding, image-compression techniques applied to radiological images are discussed in this paper. Run-length coding and Huffman coding are described, and examples are given for error-free image compression. In the case of irreversible 2D-DCT coding, the block-quantization technique and the full-frame bit-allocation (FFBA) technique are described. Error-free image compression can achieve a compression ratio from 2:1 to 3:1, whereas the irreversible 2D-DCT coding compression technique can, in general, achieve a much higher acceptable compression ratio. The currently available block-quantization hardware may lead to visible block artifacts at certain compression ratios, but FFBA may be employed with the same or higher compression ratios without generating such artifacts. An even higher compression ratio can be achieved if the image is compressed by using first FFBA and then Huffman coding. The disadvantages of FFBA are that it is sensitive to sharp edges and no hardware is available. This paper also describes the design of the FFBA technique. PMID:3598750
Systematic lossy forward error protection for error-resilient digital video broadcasting
NASA Astrophysics Data System (ADS)
Rane, Shantanu D.; Aaron, Anne; Girod, Bernd
2004-01-01
We present a novel scheme for error-resilient digital video broadcasting,using the Wyner-Ziv coding paradigm. We apply the general framework of systematic lossy source-channel coding to generate a supplementary bitstream that can correct transmission errors in the decoded video waveform up to a certain residual distortion. The systematic portion consists of a conventional MPEG-coded bitstream, which is transmitted over the error-prone channel without forward error correction.The supplementary bitstream is a low rate representation of the transmitted video sequence generated using Wyner-Ziv encoding. We use the conventionally decoded error-concealed MPEG video sequence as side information to decode the Wyner-Ziv bits. The decoder combines the error-prone side information and the Wyner-Ziv description to yield an improved decoded video signal. Our results indicate that, over a large range of channel error probabilities, this scheme yields superior video quality when compared with traditional forward error correction techniques employed in digital video broadcasting.
Performance of a phase-conjugate-engine implementing a finite-bit phase correction
Baker, K; Stappaerts, E; Wilks, S; Young, P; Gavel, D; Tucker, J; Silva, D; Olivier, S
2003-10-23
This article examines the achievable Strehl ratio when a finite-bit correction to an aberrated wave-front is implemented. The phase-conjugate-engine (PCE) used to measure the aberrated wavefront consists of a quadrature interferometric wave-front sensor, a liquid-crystal spatial-light-modulator and computer hardware/software to calculate and apply the correction. A finite-bit approximation to the conjugate phase is calculated and applied to the spatial light modulator to remove the aberrations from the optical beam. The experimentally determined Strehl ratio of the corrected beam is compared with analytical expressions for the expected Strehl ratio and shown to be in good agreement with those predictions.
Recording Density, Contact Induced Stress and Local Deformation of Bit Patterned Media
NASA Astrophysics Data System (ADS)
Shen, Shengnan; Liu, Bo; Du, Hejun
Bit-patterned media are being considered as a promising approach for achieving multi-terabit per inch recording densities. The effects of different recording density of bit-patterned media of mechanical surface loading on deformation of elastic-plastic multi-layers are analyzed by using the finite element method. The thermal protrusion of a thermal flying height control (TFC) slider and the wave surface of an elastic-plastic thin film are chosen to perform a contact analysis at the head-disk interface (HDI). A two dimensional finite element model between head and patterned media is then developed. Two patterned media cases are investigated and presented in this paper. The evolution of deformation in multi-layer media due to mechanical surface loading is presented by maximum von Mises stress and contact pressure.
Performance of multi level error correction in binary holographic memory
NASA Technical Reports Server (NTRS)
Hanan, Jay C.; Chao, Tien-Hsin; Reyes, George F.
2004-01-01
At the Optical Computing Lab in the Jet Propulsion Laboratory (JPL) a binary holographic data storage system was designed and tested with methods of recording and retrieving the binary information. Levels of error correction were introduced to the system including pixel averaging, thresholding, and parity checks. Errors were artificially introduced into the binary holographic data storage system and were monitored as a function of the defect area fraction, which showed a strong influence on data integrity. Average area fractions exceeding one quarter of the bit area caused unrecoverable errors. Efficient use of the available data density was discussed. .
Non-binary unitary error bases and quantum codes
Knill, E.
1996-06-01
Error operator bases for systems of any dimension are defined and natural generalizations of the bit-flip/ sign-change error basis for qubits are given. These bases allow generalizing the construction of quantum codes based on eigenspaces of Abelian groups. As a consequence, quantum codes can be constructed form linear codes over {ital Z}{sub {ital n}} for any {ital n}. The generalization of the punctured code construction leads to many codes which permit transversal (i.e. fault tolerant) implementations of certain operations compatible with the error basis.
One bit/s/Hz Spectrally Efficient Transmission for an Eight-Channel NRZ-Modulated DWDM System
NASA Astrophysics Data System (ADS)
Vij, Robin; Sharma, Neeraj
2016-03-01
The core of the global telecommunication network consists of wavelength-division multiplexed (WDM) optical transmission systems. WDM is the technology of choice as it allows for a high spectral efficiency. We propose an effective way to counter the nonlinearities like four-wave mixing and cross-phase modulation to achieve the spectral efficiency of 1 bit/s/Hz using non-return-to-zero (NRZ) modulation format. We use the concept of non-uniform channel spacing and non-uniform power assignment between adjacent channels of the WDM system. We have simulated an eight-channel WDM lightwave system with bit rates of 10 and 25 Gbit/s.
Preliminary design for a standard 10 sup 7 bit Solid State Memory (SSM)
NASA Technical Reports Server (NTRS)
Hayes, P. J.; Howle, W. M., Jr.; Stermer, R. L., Jr.
1978-01-01
A modular concept with three separate modules roughly separating bubble domain technology, control logic technology, and power supply technology was employed. These modules were respectively the standard memory module (SMM), the data control unit (DCU), and power supply module (PSM). The storage medium was provided by bubble domain chips organized into memory cells. These cells and the circuitry for parallel data access to the cells make up the SMM. The DCU provides a flexible serial data interface to the SMM. The PSM provides adequate power to enable one DCU and one SMM to operate simultaneously at the maximum data rate. The SSM was designed to handle asynchronous data rates from dc to 1.024 Mbs with a bit error rate less than 1 error in 10 to the eight power bits. Two versions of the SSM, a serial data memory and a dual parallel data memory were specified using the standard modules. The SSM specification includes requirements for radiation hardness, temperature and mechanical environments, dc magnetic field emission and susceptibility, electromagnetic compatibility, and reliability.
Dating cave speleothems using diamond core bits in Tennessee and Virginia
NASA Astrophysics Data System (ADS)
Burnham, T. G.; Gao, Y.; Cheng, H.; Edwards, R.
2011-12-01
Removing speleothems for paleoclimate study was a destructive practice in cave and karst communities. It was considered illegal and even resulted in lawsuits in some cases. We used small diamond core bits to investigate age distributions of speleothems in several caves in Virginia and Tennessee without removing them from caves. Core bits of 8 mm diameter and one inch depth of cut were used to drill nearly 100 cores from three caves: Morril's Cave (aka Worley's Cave) and Blue Springs Cave in Tennessee and Grand Caverns in Virginia. Samples drilled in Morrill's Cave were processed for U/Th chemistry directly. Cores drilled in Blue Springs Cave and Grand Caverns were carefully selected and cleaned using ultrasonic cleaner before the U/Th chemistry procedure. Age dating results showed significant differences for these two sets of samples. For Morril's Cave samples, most of the age errors (2 sigma) were greater than 1%. For the pre-cleaned samples, more than 90% of the age errors (2 sigma) were less than 1%. This method is non-destructive and easy to use with minimum equipment needed in the field. Age dating results are fairly precise if samples are pre-cleaned for U/Th chemistry. Major limitations of this methods are 1) Pre-cleaning is necessary to ensure precise dating results; 2) Hiatus could be missed if cores are only drilled at the top and bottom portions of the speleothems; 3) Exact location of ages are hard to interpret especially for relatively longer cores.
Simulation of bit-quantization influence on SAR-images
NASA Astrophysics Data System (ADS)
Wolframm, A. P.; Pike, T. K.
The first European Remote Sensing satellite ERS-1 has two imaging modes, the conventional Synthetic Aperture Radar (SAR) mode and the wave mode. Two quantization schemes, 2-bit and 4-bit, have been proposed for the analogue-to-digital conversion of the video signal of the ERS-1 wave mode. This paper analyzes the influence of these two quantization schemes on ocean-wave spectra. The SAR-images were obtained through simulation using a static oceanwave radar model and a comprehensive software SAR-system simulation model (SARSIM) on the DFVLR computing system. The results indicate that spectra produced by the 4-bit quantization are not significantly degraded from the optimum, but that the 2-bit quantization requires some gain adjustment for optimal spectral reproduction. The conclusions are supported by images and spectral plots covering the various options simulated.
Bit selection increases coiled tubing and slimhole success
Feiner, R.F.
1995-07-01
Slimhole applications have grown within the past few years to include deepening existing wells to untapped reservoirs, drilling smaller well programs to reduce tangible costs and recompleting wells to adjacent reservoirs through directional or horizontal sidetracks. When selecting the proper bit for an interval, the ultimate goal is the same in the slimhole application as in the conventional application -- to save the operator money by reducing drilling cost per foot (CPF). Slimhole bit selection is a three-step process: (1) identify the characteristics of the formations to be drilled; (2) analyze the operational limitations of the slimhole application; and (3) select the bit type that will most economically drill the interval. Knowledge of lithology is crucial to the selection process. Accurate formation knowledge can be acquired from offset well records, mud logs, cores, electric logs, compressive rock strength analysis and any other information relevant to the drilling operation. This paper reviews the steps in selecting slimhole bits and completion equipment.
Experimental bit commitment based on quantum communication and special relativity.
Lunghi, T; Kaniewski, J; Bussières, F; Houlmann, R; Tomamichel, M; Kent, A; Gisin, N; Wehner, S; Zbinden, H
2013-11-01
Bit commitment is a fundamental cryptographic primitive in which Bob wishes to commit a secret bit to Alice. Perfectly secure bit commitment between two mistrustful parties is impossible through asynchronous exchange of quantum information. Perfect security is however possible when Alice and Bob split into several agents exchanging classical and quantum information at times and locations suitably chosen to satisfy specific relativistic constraints. Here we report on an implementation of a bit commitment protocol using quantum communication and special relativity. Our protocol is based on [A. Kent, Phys. Rev. Lett. 109, 130501 (2012)] and has the advantage that it is practically feasible with arbitrary large separations between the agents in order to maximize the commitment time. By positioning agents in Geneva and Singapore, we obtain a commitment time of 15 ms. A security analysis considering experimental imperfections and finite statistics is presented. PMID:24237497
Secure self-calibrating quantum random-bit generator
Fiorentino, M.; Santori, C.; Spillane, S. M.; Beausoleil, R. G.; Munro, W. J.
2007-03-15
Random-bit generators (RBGs) are key components of a variety of information processing applications ranging from simulations to cryptography. In particular, cryptographic systems require 'strong' RBGs that produce high-entropy bit sequences, but traditional software pseudo-RBGs have very low entropy content and therefore are relatively weak for cryptography. Hardware RBGs yield entropy from chaotic or quantum physical systems and therefore are expected to exhibit high entropy, but in current implementations their exact entropy content is unknown. Here we report a quantum random-bit generator (QRBG) that harvests entropy by measuring single-photon and entangled two-photon polarization states. We introduce and implement a quantum tomographic method to measure a lower bound on the 'min-entropy' of the system, and we employ this value to distill a truly random-bit sequence. This approach is secure: even if an attacker takes control of the source of optical states, a secure random sequence can be distilled.
8-Bit Gray Scale Images of Fingerprint Image Groups
National Institute of Standards and Technology Data Gateway
NIST 8-Bit Gray Scale Images of Fingerprint Image Groups (PC database for purchase) The NIST database of fingerprint images contains 2000 8-bit gray scale fingerprint image pairs. A newer version of the compression/decompression software on the CDROM can be found at the website http://www.nist.gov/itl/iad/ig/nigos.cfm as part of the NBIS package.
Eight-Bit-Slice GaAs General Processor Circuit
NASA Technical Reports Server (NTRS)
Weissman, John; Gauthier, Robert V.
1989-01-01
Novel GaAs 8-bit slice enables quick and efficient implementation of variety of fast GaAs digital systems ranging from central processing units of computers to special-purpose processors for communications and signal-processing applications. With GaAs 8-bit slice, designers quickly configure and test hearts of many digital systems that demand fast complex arithmetic, fast and sufficient register storage, efficient multiplexing and routing of data words, and ease of control.
Tuned support for cutting elements in a drag bit
Evans, R.F.
1984-10-23
Harmonic resonation of cutting elements against the earth formation is impeded in a rotary drag-type drill bit by providing connection means which yieldably and resiliently support the cutting elements from the drill bit but which deflects or vibrates with different natural resonant harmonic frequencies. The different natural harmonic frequencies tend to cancel or nullify resonance of any one of the connection means. The connection means can also be externally damped against vibrational movement.
Drill-bit with full offset cutter bodies
Frear, L.
1985-11-12
A rotary drag drill bit is seen wherein cutter bodies are rotatively connected to a main body structure at a fully offset position. The fully offset position is defined by a rotational axis of each cutter body, a longitudinal axis of the drill bit and end support points or positions of the cutter bodies. The rotational axes of the cutter bodies are perpendicular to the longitudinal axis of the drill bit. The end supports of the cutter body are each equal distance from any point on the longitudinal axis of the drill bit. The cutter bodies of essentially ellipsoidal configuration, being slightly thicker at a mid-portion thereof. Cutting elements are connected to flutes projecting above an outer surface of each cutter body. In a primary rotational direction of the drill string and drill bit, the rows abrade the bottom and side walls of a well bore as the cutter body attacks the earth formation as the drill bit is rotated. The impingement of the cutting elements of the cutter body on the earth formation imparts a secondary rotation to the cutter bodies, which secondary rotation is induced by the primary rotation. The secondary rotation allows the rows of cutting elements to engage the side wall of the bore and gauge the hole as well as abrading away material from the bottom of the well bore. A roller bearing assembly is provided for the cutter body to permit the secondary rotation, while a thrust bearing assembly assists the primary abrasive action imparted by the primary rotational movement of the rotary drill bit. A lubrication system is included in the main body structure of the drill bit wherein both the roller bearing assembly and thrust bearing assembly are lubricated.
Strong no-go theorem for Gaussian quantum bit commitment
Magnin, Loieck; Magniez, Frederic; Leverrier, Anthony
2010-01-15
Unconditionally secure bit commitment is forbidden by quantum mechanics. We extend this no-go theorem to continuous-variable protocols where both players are restricted to use Gaussian states and operations, which is a reasonable assumption in current-state optical implementations. Our Gaussian no-go theorem also provides a natural counter-example to a conjecture that quantum mechanics can be rederived from the assumption that key distribution is allowed while bit commitment is forbidden in Nature.
Bit allocation for joint coding of multiple video programs
NASA Astrophysics Data System (ADS)
Wang, Limin; Vincent, Andre
1997-01-01
By dynamically distributing the channel capacity among video programs according to their respective scene complexities, joint coding has been a shown to be more efficient than independent coding for compression of multiple video programs. This paper examines the bit allocation issue for joint coding of multiple video programs and provides a bit allocation strategy that results in uniform picture quality among programs as will as within a program.
NASA Astrophysics Data System (ADS)
Turcotte, Randy L.; Wickert, Mark A.
An exact expression is found for the probability of bit error of an FHSS-BFSK (frequency-hopping spread-spectrum/binary-frequency-shift-keying) multiple-access system in the presence of slow, nonselective, 'single-term' Rician fading. The effects of multiple-access interference and/or continuous tone jamming are considered. Comparisons are made between the error expressions developed here and previously published upper bounds. It is found that under certain channel conditions the upper bounds on the probability of bit error may exceed the actual probability of error by an order of magnitude.
NASA Astrophysics Data System (ADS)
Olsen, Donald P.; Wang, Charles C.; Sklar, Dean; Huang, Bormin; Ahuja, Alok
2005-08-01
Research has been undertaken to examine the robustness of JPEG2000 when corrupted by transmission bit errors in a satellite data stream. Contemporary and future ultraspectral sounders such as Atmospheric Infrared Sounder (AIRS), Cross-track Infrared Sounder (CrIS), Infrared Atmospheric Sounding Interferometer (IASI), Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS), and Hyperspectral Environmental Suite (HES) generate a large volume of three-dimensional data. Hence, compression of ultraspectral sounder data will facilitate data transmission and archiving. There is a need for lossless or near-lossless compression of ultraspectral sounder data to avoid potential retrieval degradation of geophysical parameters due to lossy compression. This paper investigates the simulated error propagation in AIRS ultraspectral sounder data with advanced source and channel coding in a satellite data stream. The source coding is done via JPEG2000, the latest International Organization for Standardization (ISO)/International Telecommunication Union (ITU) standard for image compression. After JPEG2000 compression the AIRS ultraspectral sounder data is then error correction encoded using a rate 0.954 turbo product code (TPC) for channel error control. Experimental results of error patterns on both channel and source decoding are presented. The error propagation effects are curbed via the block-based protection mechanism in the JPEG2000 codec as well as memory characteristics of the forward error correction (FEC) scheme to contain decoding errors within received blocks. A single nonheader bit error in a source code block tends to contaminate the bits until the end of the source code block before the inverse discrete wavelet transform (IDWT), and those erroneous bits propagate even further after the IDWT. Furthermore, a single header bit error may result in the corruption of almost the entire decompressed granule. JPEG2000 appears vulnerable to bit errors in a noisy channel of
Bias and spread in extreme value theory measurements of probability of error
NASA Technical Reports Server (NTRS)
Smith, J. G.
1972-01-01
Extreme value theory is examined to explain the cause of the bias and spread in performance of communications systems characterized by low bit rates and high data reliability requirements, for cases in which underlying noise is Gaussian or perturbed Gaussian. Experimental verification is presented and procedures that minimize these effects are suggested. Even under these conditions, however, extreme value theory test results are not particularly more significant than bit error rate tests.
Fast decoding techniques for extended single-and-double-error-correcting Reed Solomon codes
NASA Technical Reports Server (NTRS)
Costello, D. J., Jr.; Deng, H.; Lin, S.
1984-01-01
A problem in designing semiconductor memories is to provide some measure of error control without requiring excessive coding overhead or decoding time. For example, some 256K-bit dynamic random access memories are organized as 32K x 8 bit-bytes. Byte-oriented codes such as Reed Solomon (RS) codes provide efficient low overhead error control for such memories. However, the standard iterative algorithm for decoding RS codes is too slow for these applications. Some special high speed decoding techniques for extended single and double error correcting RS codes. These techniques are designed to find the error locations and the error values directly from the syndrome without having to form the error locator polynomial and solve for its roots.
An adaptive error modeling scheme for the lossless compression of EEG signals.
Sriraam, N; Eswaran, C
2008-09-01
Lossless compression of EEG signal is of great importance for the neurological diagnosis as the specialists consider the exact reconstruction of the signal as a primary requirement. This paper discusses a lossless compression scheme for EEG signals that involves a predictor and an adaptive error modeling technique. The prediction residues are arranged based on the error count through an histogram computation. Two optimal regions are identified in the histogram plot through a heuristic search such that the bit requirement for encoding the two regions is minimum. Further improvement in the compression is achieved by removing the statistical redundancy that is present in the residue signal by using a context-based bias cancellation scheme. Three neural network predictors, namely, single-layer perceptron, multilayer perceptron, and Elman network and two linear predictors, namely, autoregressive model and finite impulse response filter are considered. Experiments are conducted using EEG signals recorded under different physiological conditions and the performances of the proposed methods are evaluated in terms of the compression ratio. It is shown that the proposed adaptive error modeling schemes yield better compression results compared to other known compression methods. PMID:18779073
Soft-decision forward error correction for 100 Gb/s digital coherent systems
NASA Astrophysics Data System (ADS)
Onohara, Kiyoshi; Sugihara, Takashi; Miyata, Yoshikuni; Sugihara, Kenya; Kubo, Kazuo; Yoshida, Hideo; Koguchi, Kazuumi; Mizuochi, Takashi
2011-10-01
Soft-decision forward error correction (SD-FEC) and its practical implementation for 100 Gb/s digital coherent systems are discussed. In applying SD-FEC to a digital coherent transponder, the configuration of the frame structure of the FEC becomes a key issue. We present a triple-concatenated FEC, with a pair of concatenated hard-decision FEC (HD-FEC) further concatenated with an SD-based low-density parity-check (LDPC) code for 20.5% redundancy. In order to evaluate error correcting performance of SD-based LDPC code. We implement the entire 100 Gb/s throughput of LDPC code on field programmable gate arrays (FPGAs) based hardware emulator. The proposed triple-concatenated FEC can achieve a Q-limit of 6.4 dB and a net coding gain (NCG) of 10.8 dB at a post-FEC bit error ratio (BER) of 10 -15 is expected. In addition, we raise an important question for the definition of NCG in digital coherent systems with and without differential quadrature phase-shift keying (QPSK) coding, which is generally used to avoid phase slip caused by the practical limitations in processing the phase recovery algorithms.
Error Control Techniques for Satellite and Space Communications
NASA Technical Reports Server (NTRS)
Costello, Daniel J., Jr.
1996-01-01
In this report, we present the results of our recent work on turbo coding in two formats. Appendix A includes the overheads of a talk that has been given at four different locations over the last eight months. This presentation has received much favorable comment from the research community and has resulted in the full-length paper included as Appendix B, 'A Distance Spectrum Interpretation of Turbo Codes'. Turbo codes use a parallel concatenation of rate 1/2 convolutional encoders combined with iterative maximum a posteriori probability (MAP) decoding to achieve a bit error rate (BER) of 10(exp -5) at a signal-to-noise ratio (SNR) of only 0.7 dB. The channel capacity for a rate 1/2 code with binary phase shift-keyed modulation on the AWGN (additive white Gaussian noise) channel is 0 dB, and thus the Turbo coding scheme comes within 0.7 DB of capacity at a BER of 10(exp -5).
a Josephson Bit-Serial Decoder for Application in a Crossbar Switch.
NASA Astrophysics Data System (ADS)
Feld, David Albert
This dissertation describes the design, analysis, fabrication, and testing of a fully functional 5-32 bit -serial digital decoder comprising 299 Josephson junctions. A two-micron Josephson junction technology was used to realize performance characteristics: (a) 5 bit serial address is applied at 2 Gbit/s; (b) decode time (from start signal to output) is 350 ps; (c) average power = 500 muW; (d) power supply current <15 mA; (e) area is 0.5 mm x 1.7 mm (2 μm wires); (f) clocking done with one power clock and one signal clock (synchronized with data). This decoder can be incorporated as part of a crossbar switch to be used to interconnect a large number of microprocessors and memories. Of course, it could also be used as part of a Josephson memory. The decoder has two major parts: (1) a 5-bit serial-to-parallel converter and (2) a 5-32 bit-parallel decoder. We discuss operation of this serial-to-parallel converter as well as the problems which were encountered and finally solved. The second part of the project was fully designed by the author. The author proposed novel NOR gates to be able to achieve the design constraints. The novel NOR gates were fabricated by the author in the Berkeley Microfabrication Laboratory and functionality of these gates was demonstrated. The rest of the fabrication was done at Hypres Inc. The author submitted several designs to Hypres where all of the design flaws were worked out. The serial-to-parallel converter and parallel decoder were demonstrated to be fully functional at low speeds. Then the two parts were interconnected and the complete bit-serial-decoder was demonstrated to be fully functional. Finally the author demonstrated operation of the circuit at a bit-serial input rate of 2 Gigabit/s. A variety of experimental and theoretical circuit problems were encountered during the development of this circuit and these problems are discussed in detail. Among these are resonance problems in two-junction SQUIDs, resonances in stacks of
Non-Abelian quantum error correction
NASA Astrophysics Data System (ADS)
Feng, Weibo
A quantum computer is a proposed device which would be capable of initializing, coherently manipulating, and measuring quantum states with sufficient accuracy to carry out new kinds of computations. In the standard scenario, a quantum computer is built out of quantum bits, or qubits, two-level quantum systems which replace the ordinary classical bits of a classical computer. Quantum computation is then carried out by applying quantum gates, the quantum equivalent of Boolean logic gates, to these qubits. The most fundamental barrier to building a quantum computer is the inevitable errors which occur when carrying out quantum gates and the loss of quantum coherence of the qubits due to their coupling to the environment (decoherence). Remarkably, it has been shown that in a quantum computer such errors and decoherence can be actively fought using what is known as quantum error correction. A closely related proposal for fighting errors and decoherence in a quantum computer is to build the computer out of so-called topologically ordered states of matter. These are states of matter which allow for the storage and manipulation of quantum states with a built in protection from error and decoherence. The excitations of these states are non-Abelian anyons, particle-like excitations which satisfy non-Abelian statistics, meaning that when two excitations are interchanged the result is not the usual +1 and -1 associated with identical Bosons or Fermions, but rather a unitary operation which acts on a multidimensional Hilbert space. It is therefore possible to envision computing with these anyons by braiding their world-lines in 2+1-dimensional spacetime. In this Dissertation we present explicit procedures for a scheme which lives at the intersection of these two approaches. In this scheme we envision a functioning ``conventional" quantum computer consisting of an array of qubits and the ability to carry out quantum gates on these qubits. We then give explicit quantum circuits
Achieving the Holevo bound via a bisection decoding protocol
NASA Astrophysics Data System (ADS)
Rosati, Matteo; Giovannetti, Vittorio
2016-06-01
We present a new decoding protocol to realize transmission of classical information through a quantum channel at asymptotically maximum capacity, achieving the Holevo bound and thus the optimal communication rate. At variance with previous proposals, our scheme recovers the message bit by bit, making use of a series of "yes-no" measurements, organized in bisection fashion, thus determining which codeword was sent in log2 N steps, N being the number of codewords.
Jhurani, Chetan; Austin, Travis M.; Heroux, Michael Allen; Willenbring, James Michael
2013-06-01
The Trilinos Project is an effort to facilitate the design, development, integration and ongoing support of mathematical software libraries within an object-oriented framework. It is intended for large-scale, complex multiphysics engineering and scientific applications [2, 4, 3]. Epetra is one of its basic packages. It provides serial and parallel linear algebra capabilities. Before Trilinos version 11.0, released in 2012, Epetra used the C++ int data-type for storing global and local indices for degrees of freedom (DOFs). Since int is typically 32-bit, this limited the largest problem size to be smaller than approximately two billion DOFs. This was true even if a distributed memory machine could handle larger problems. We have added optional support for C++ long long data-type, which is at least 64-bit wide, for global indices. To save memory, maintain the speed of memory-bound operations, and reduce further changes to the code, the local indices are still 32-bit. We document the changes required to achieve this feature and how the new functionality can be used. We also report on the lessons learned in modifying a mature and popular package from various perspectives - design goals, backward compatibility, engineering decisions, C++ language features, effects on existing users and other packages, and build integration.
Medical image compression using cubic spline interpolation with bit-plane compensation
NASA Astrophysics Data System (ADS)
Truong, Trieu-Kien; Chen, Shi-Huang; Lin, Tsung-Ching
2007-03-01
In this paper, a modified medical image compression algorithm using cubic spline interpolation (CSI) is presented for telemedicine applications. The CSI is developed in order to subsample image data with minimal distortion and to achieve compression. It has been shown in literatures that the CSI can be combined with the JPEG algorithms to develop a modified JPEG codec, which obtains a higher compression ratio and a better quality of reconstructed image than the standard JPEG. However, this modified JPEG codec will lose some high-frequency components of medical images during compression process. To minimize the drawback arose from loss of these high-frequency components, this paper further makes use of bit-plane compensation to the modified JPEG codec. The bit-plane compensation algorithm used in this paper is modified from JBIG2 standard. Experimental results show that the proposed scheme can increase 20~30% compression ratio of original JPEG medical data compression system with similar visual quality. This system can reduce the loading of telecommunication networks and is quite suitable for low bit-rate telemedicine applications.
Multidimensional bit-rate control for video communication
NASA Astrophysics Data System (ADS)
Reed, Eric C.; Lim, Jae S.
2000-12-01
In conventional bit rate control schemes, the buffer level is controlled by adjusting the quantization step size while the frame rate and spatial resolution chosen for coding are fixed throughout the coding process. In this paper, we consider a more general Multidimensional (M-D) bit rate control where the frame rate, spatial resolution and quantization step size are jointly adapted for buffer control. In the M-D bit rate control setting, the problem is to decide which frames to code (and which frames to skip) along with the spatial resolution and the quantization step size to use for each coded frame. Given a finite set of operating points on a M-D grid, we formulate the optimal solution of the M-D buffer-constrained allocation problem. The formulation allows a skipped frame to be reconstructed from one coded frame using any temporal interpolation method. A dynamic programming algorithm is presented to obtain an optimal solution for the case of intraframe coding which is a special case of dependent coding. We experiment with both zero-order hold and motion-compensated temporal interpolation. Operational rate-distortion (R-D) bounds are illustrated for both the M-D and conventional bit rate control approaches. Our focus is one very low bit rate applications where a significant delay is tolerable.
A 100 MS/s 9 bit 0.43 mW SAR ADC with custom capacitor array
NASA Astrophysics Data System (ADS)
Jingjing, Wang; Zemin, Feng; Rongjin, Xu; Chixiao, Chen; Fan, Ye; Jun, Xu; Junyan, Ren
2016-05-01
A low power 9 bit 100 MS/s successive approximation register analog-to-digital converter (SAR ADC) with custom capacitor array is presented. A brand-new 3-D MOM unit capacitor is used as the basic capacitor cell of this capacitor array. The unit capacitor has a capacitance of 1 fF. Besides, the advanced capacitor array structure and switch mode decrease the power consumption a lot. To verify the effectiveness of this low power design, the 9 bit 100 MS/s SAR ADC is implemented in TSMC IP9M 65 nm LP CMOS technology. The measurement results demonstrate that this design achieves an effective number of bits (ENOB) of 7.4 bit, a signal-to-noise plus distortion ratio (SNDR) of 46.40 dB and a spurious-free dynamic range (SFDR) of 62.31 dB at 100 MS/s with 1 MHz input. The SAR ADC core occupies an area of 0.030 mm2 and consumes 0.43 mW under a supply voltage of 1.2 V. The figure of merit (FOM) of the SAR ADC achieves 23.75 fJ/conv. Project supported by the National High-Tech Research and Development Program of China (No. 2013AA014101).
Elliott, C.J.; McVey, B. ); Quimby, D.C. )
1990-01-01
The level of field errors in an FEL is an important determinant of its performance. We have computed 3D performance of a large laser subsystem subjected to field errors of various types. These calculations have been guided by simple models such as SWOOP. The technique of choice is utilization of the FELEX free electron laser code that now possesses extensive engineering capabilities. Modeling includes the ability to establish tolerances of various types: fast and slow scale field bowing, field error level, beam position monitor error level, gap errors, defocusing errors, energy slew, displacement and pointing errors. Many effects of these errors on relative gain and relative power extraction are displayed and are the essential elements of determining an error budget. The random errors also depend on the particular random number seed used in the calculation. The simultaneous display of the performance versus error level of cases with multiple seeds illustrates the variations attributable to stochasticity of this model. All these errors are evaluated numerically for comprehensive engineering of the system. In particular, gap errors are found to place requirements beyond mechanical tolerances of {plus minus}25{mu}m, and amelioration of these may occur by a procedure utilizing direct measurement of the magnetic fields at assembly time. 4 refs., 12 figs.
Compiler-Assisted Detection of Transient Memory Errors
Tavarageri, Sanket; Krishnamoorthy, Sriram; Sadayappan, Ponnuswamy
2014-06-09
The probability of bit flips in hardware memory systems is projected to increase significantly as memory systems continue to scale in size and complexity. Effective hardware-based error detection and correction requires that the complete data path, involving all parts of the memory system, be protected with sufficient redundancy. First, this may be costly to employ on commodity computing platforms and second, even on high-end systems, protection against multi-bit errors may be lacking. Therefore, augmenting hardware error detection schemes with software techniques is of consider- able interest. In this paper, we consider software-level mechanisms to comprehensively detect transient memory faults. We develop novel compile-time algorithms to instrument application programs with checksum computation codes so as to detect memory errors. Unlike prior approaches that employ checksums on computational and architectural state, our scheme verifies every data access and works by tracking variables as they are produced and consumed. Experimental evaluation demonstrates that the proposed comprehensive error detection solution is viable as a completely software-only scheme. We also demonstrate that with limited hardware support, overheads of error detection can be further reduced.
Image steganography based on 2k correction and coherent bit length
NASA Astrophysics Data System (ADS)
Sun, Shuliang; Guo, Yongning
2014-10-01
In this paper, a novel algorithm is proposed. Firstly, the edge of cover image is detected with Canny operator and secret data is embedded in edge pixels. Sorting method is used to randomize the edge pixels in order to enhance security. Coherent bit length L is determined by relevant edge pixels. Finally, the method of 2k correction is applied to achieve better imperceptibility in stego image. The experiment shows that the proposed method is better than LSB-3 and Jae-Gil Yu's in PSNR and capacity.
NASA Astrophysics Data System (ADS)
Serpelloni, Edoardo; Maggiore, Manfredi; Damaren, Christopher J.
2015-02-01
This paper investigates a formation control problem for two space vehicles in the vicinity of the L 2 libration point of the Sun-Earth/Moon system. The objective is to accurately regulate the relative position vector between the vehicles to a desired configuration, under tight tolerances. It is shown that the formation control problem is solvable using six constant thrust electric actuators requiring only one bit of resolution, and bounded switching frequency. The proposed control law is hybrid, and it coordinates the sequence of on-off switches of the thrusters so as to achieve the control objective and, at the same time, avoid high-frequency switching.
Performance analysis of a hybrid ARQ error control scheme for near earth satellite communications
NASA Technical Reports Server (NTRS)
Lin, Shu
1987-01-01
A robust error control coding scheme is presented. The scheme is a cascaded forward error correction (FEC) scheme supported by parity retransmissions for further error correction in the erroneous data words. The error performance and throughput efficiency of the scheme are analyzed. Two specific schemes are proposed for NASA near earth satellite communications. It is shown that both schemes provide high reliability and throughput efficiency even for high channel bit error rates in the range of .002. The schemes are suitable for high data rate file transfer.
Metabolism - inborn errors of ... Bodamer OA. Approach to inborn errors of metabolism. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine . 25th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 205. Rezvani I, Rezvani G. An ...
Fully photonics-based physical random bit generator.
Li, Pu; Sun, Yuanyuan; Liu, Xianglian; Yi, Xiaogang; Zhang, Jianguo; Guo, Xiaomin; Guo, Yanqiang; Wang, Yuncai
2016-07-15
We propose a fully photonics-based approach for ultrafast physical random bit generation. This approach exploits a compact nonlinear loop mirror (called a terahertz optical asymmetric demultiplexer, TOAD) to sample the chaotic optical waveform in an all-optical domain and then generate random bit streams through further comparison with a threshold level. This method can efficiently overcome the electronic jitter bottleneck confronted by existing RBGs in practice. A proof-of-concept experiment demonstrates that this method can continuously extract 5 Gb/s random bit streams from the chaotic output of a distributed feedback laser diode (DFB-LD) with optical feedback. This limited generation rate is caused by the bandwidth of the used optical chaos. PMID:27420532
Security bound of cheat sensitive quantum bit commitment
He, Guang Ping
2015-01-01
Cheat sensitive quantum bit commitment (CSQBC) loosens the security requirement of quantum bit commitment (QBC), so that the existing impossibility proofs of unconditionally secure QBC can be evaded. But here we analyze the common features in all existing CSQBC protocols, and show that in any CSQBC having these features, the receiver can always learn a non-trivial amount of information on the sender's committed bit before it is unveiled, while his cheating can pass the security check with a probability not less than 50%. The sender's cheating is also studied. The optimal CSQBC protocols that can minimize the sum of the cheating probabilities of both parties are found to be trivial, as they are practically useless. We also discuss the possibility of building a fair protocol in which both parties can cheat with equal probabilities. PMID:25796977
New bits, motors improve economics of slim hole horizontal wells
McDonald, S.; Felderhoff, F.; Fisher, K.
1996-03-11
The latest generation of small-diameter bits, combined with a new extended power section positive displacement motor (PDM), has improved the economics of slim hole drilling programs. As costs are driven down, redevelopment reserves are generated in the older, more established fields. New reserves result from increases in the ultimate recovery and accelerated production rates from the implementation of horizontal wells in reentry programs. This logic stimulated an entire development program for a Gulf of Mexico platform, which was performed without significant compromises in well bore geometry. The savings from this new-generation drilling system come from reducing the total number of trips required during the drilling phase. This paper reviews the design improvements of roller cone bits, PDC bits, and positive displacement motors for offshore directional drilling operations.
Unconditionally secure bit commitment by transmitting measurement outcomes.
Kent, Adrian
2012-09-28
We propose a new unconditionally secure bit commitment scheme based on Minkowski causality and the properties of quantum information. The receiving party sends a number of randomly chosen Bennett-Brassard 1984 (BB84) qubits to the committer at a given point in space-time. The committer carries out measurements in one of the two BB84 bases, depending on the committed bit value, and transmits the outcomes securely at (or near) light speed in opposite directions to remote agents. These agents unveil the bit by returning the outcomes to adjacent agents of the receiver. The protocol's security relies only on simple properties of quantum information and the impossibility of superluminal signalling. PMID:23030073
Decision-fusion-based automated drill bit toolmark correlator
NASA Astrophysics Data System (ADS)
Jones, Brett C.; Press, Michael J.; Guerci, Joseph R.
1999-02-01
This paper describes a recent study conducted to investigate the reproducibility of toolmarks left by drill bits. This paper focuses on the automated analysis aspect of the study, and particularly the advantages of using decision fusion methods in the comparisons. To enable the study to encompass a large number of samples, existing technology was adapted to the task of automatically comparing the test impressions. Advanced forensic pattern recognition algorithms that had been developed for the comparison of ballistic evidence in the DRUGFIRETM system were modified for use in this test. The results of the decision fusion architecture closely matched those obtained by expert visual examination. The study, aided by the improved pattern recognition algorithm, showed that drill bit impressions do contain reproducible marks. In a blind test, the DRUGFIRE pattern recognition algorithm, enhanced with the decision fusion architecture, consistently identified the correct bit as the source of the test impressions.
Security bound of cheat sensitive quantum bit commitment
NASA Astrophysics Data System (ADS)
He, Guang Ping
2015-03-01
Cheat sensitive quantum bit commitment (CSQBC) loosens the security requirement of quantum bit commitment (QBC), so that the existing impossibility proofs of unconditionally secure QBC can be evaded. But here we analyze the common features in all existing CSQBC protocols, and show that in any CSQBC having these features, the receiver can always learn a non-trivial amount of information on the sender's committed bit before it is unveiled, while his cheating can pass the security check with a probability not less than 50%. The sender's cheating is also studied. The optimal CSQBC protocols that can minimize the sum of the cheating probabilities of both parties are found to be trivial, as they are practically useless. We also discuss the possibility of building a fair protocol in which both parties can cheat with equal probabilities.
Can relativistic bit commitment lead to secure quantum oblivious transfer?
NASA Astrophysics Data System (ADS)
He, Guang Ping
2015-05-01
While unconditionally secure bit commitment (BC) is considered impossible within the quantum framework, it can be obtained under relativistic or experimental constraints. Here we study whether such BC can lead to secure quantum oblivious transfer (QOT). The answer is not completely negative. In one hand, we provide a detailed cheating strategy, showing that the "honest-but-curious adversaries" in some of the existing no-go proofs on QOT still apply even if secure BC is used, enabling the receiver to increase the average reliability of the decoded value of the transferred bit. On the other hand, it is also found that some other no-go proofs claiming that a dishonest receiver can always decode all transferred bits simultaneously with reliability 100% become invalid in this scenario, because their models of cryptographic protocols are too ideal to cover such a BC-based QOT.
Security bound of cheat sensitive quantum bit commitment.
He, Guang Ping
2015-01-01
Cheat sensitive quantum bit commitment (CSQBC) loosens the security requirement of quantum bit commitment (QBC), so that the existing impossibility proofs of unconditionally secure QBC can be evaded. But here we analyze the common features in all existing CSQBC protocols, and show that in any CSQBC having these features, the receiver can always learn a non-trivial amount of information on the sender's committed bit before it is unveiled, while his cheating can pass the security check with a probability not less than 50%. The sender's cheating is also studied. The optimal CSQBC protocols that can minimize the sum of the cheating probabilities of both parties are found to be trivial, as they are practically useless. We also discuss the possibility of building a fair protocol in which both parties can cheat with equal probabilities. PMID:25796977
Analysis of error-correction constraints in an optical disk.
Roberts, J D; Ryley, A; Jones, D M; Burke, D
1996-07-10
The compact disk read-only memory (CD-ROM) is a mature storage medium with complex error control. It comprises four levels of Reed Solomon codes allied to a sequence of sophisticated interleaving strategies and 8:14 modulation coding. New storage media are being developed and introduced that place still further demands on signal processing for error correction. It is therefore appropriate to explore thoroughly the limit of existing strategies to assess future requirements. We describe a simulation of all stages of the CD-ROM coding, modulation, and decoding. The results of decoding the burst error of a prescribed number of modulation bits are discussed in detail. Measures of residual uncorrected error within a sector are displayed by C1, C2, P, and Q error counts and by the status of the final cyclic redundancy check (CRC). Where each data sector is encoded separately, it is shown that error-correction performance against burst errors depends critically on the position of the burst within a sector. The C1 error measures the burst length, whereas C2 errors reflect the burst position. The performance of Reed Solomon product codes is shown by the P and Q statistics. It is shown that synchronization loss is critical near the limits of error correction. An example is given of miscorrection that is identified by the CRC check. PMID:21102793
ERIC Educational Resources Information Center
Kearsley, Greg P.
This paper discusses and provides some preliminary data on errors in APL programming. Data were obtained by analyzing listings of 148 complete and partial APL sessions collected from student terminal rooms at the University of Alberta. Frequencies of errors for the various error messages are tabulated. The data, however, are limited because they…
NASA Astrophysics Data System (ADS)
Zhang, Ruimao; Lin, Liang; Zhang, Rui; Zuo, Wangmeng; Zhang, Lei
2015-12-01
Extracting informative image features and learning effective approximate hashing functions are two crucial steps in image retrieval . Conventional methods often study these two steps separately, e.g., learning hash functions from a predefined hand-crafted feature space. Meanwhile, the bit lengths of output hashing codes are preset in most previous methods, neglecting the significance level of different bits and restricting their practical flexibility. To address these issues, we propose a supervised learning framework to generate compact and bit-scalable hashing codes directly from raw images. We pose hashing learning as a problem of regularized similarity learning. Specifically, we organize the training images into a batch of triplet samples, each sample containing two images with the same label and one with a different label. With these triplet samples, we maximize the margin between matched pairs and mismatched pairs in the Hamming space. In addition, a regularization term is introduced to enforce the adjacency consistency, i.e., images of similar appearances should have similar codes. The deep convolutional neural network is utilized to train the model in an end-to-end fashion, where discriminative image features and hash functions are simultaneously optimized. Furthermore, each bit of our hashing codes is unequally weighted so that we can manipulate the code lengths by truncating the insignificant bits. Our framework outperforms state-of-the-arts on public benchmarks of similar image search and also achieves promising results in the application of person re-identification in surveillance. It is also shown that the generated bit-scalable hashing codes well preserve the discriminative powers with shorter code lengths.
Zhang, Ruimao; Lin, Liang; Zhang, Rui; Zuo, Wangmeng; Zhang, Lei
2015-12-01
Extracting informative image features and learning effective approximate hashing functions are two crucial steps in image retrieval. Conventional methods often study these two steps separately, e.g., learning hash functions from a predefined hand-crafted feature space. Meanwhile, the bit lengths of output hashing codes are preset in the most previous methods, neglecting the significance level of different bits and restricting their practical flexibility. To address these issues, we propose a supervised learning framework to generate compact and bit-scalable hashing codes directly from raw images. We pose hashing learning as a problem of regularized similarity learning. In particular, we organize the training images into a batch of triplet samples, each sample containing two images with the same label and one with a different label. With these triplet samples, we maximize the margin between the matched pairs and the mismatched pairs in the Hamming space. In addition, a regularization term is introduced to enforce the adjacency consistency, i.e., images of similar appearances should have similar codes. The deep convolutional neural network is utilized to train the model in an end-to-end fashion, where discriminative image features and hash functions are simultaneously optimized. Furthermore, each bit of our hashing codes is unequally weighted, so that we can manipulate the code lengths by truncating the insignificant bits. Our framework outperforms state-of-the-arts on public benchmarks of similar image search and also achieves promising results in the application of person re-identification in surveillance. It is also shown that the generated bit-scalable hashing codes well preserve the discriminative powers with shorter code lengths. PMID:26276992
Bit-related lesions in Icelandic competition horses
2014-01-01
Background Oral lesions related to the use of the bit and bridle are reported to be common findings in horses worldwide and represent an important animal welfare issue. In order to provide an overview of bit-related lesions in Icelandic competition horses, a field examination of the rostral part of the oral cavity was performed in 424 competition horses coming to the two major national horse events in Iceland in 2012. Records from repeated examination of 77 horses prior to the finals were used to assess potential risk factors. Results Mild lesions were recorded in 152 horses (36%) prior to the preliminary rounds. They were most often located in the commissures of the lips and the adjacent buccal mucosa (n = 111). Severe lesions were found in 32 (8%) horses. For 77 horses examined prior to the finals, the frequency of findings in the area of the mandibular interdental space (bars of the mandible) had increased from 8% to 31% (P < 0.0001). These findings were most often (16/24) regarded as severe. The presence of lesions on the bars was strongly associated to the use of curb bits with a port (OR = 75, P = 0.009). Conclusions Bit-related lesions were found to be a general problem in Icelandic competition horses. The type of bits used influenced both the location and the severity of the lesions. The use of curb bits with a port was found to be a decisive risk factor for lesions on the bars of the mandible, most of which were regarded as severe. The results also raised questions about the head and neck carriage demanded for the competition horses. PMID:25116656
NASA Astrophysics Data System (ADS)
Kaiser, F.; Aktas, D.; Fedrici, B.; Lunghi, T.; Labonté, L.; Tanzilli, S.
2016-06-01
We demonstrate an experimental method for measuring energy-time entanglement over almost 80 nm spectral bandwidth in a single shot with a quantum bit error rate below 0.5%. Our scheme is extremely cost-effective and efficient in terms of resources as it employs only one source of entangled photons and one fixed unbalanced interferometer per phase-coded analysis basis. We show that the maximum analysis spectral bandwidth is obtained when the analysis interferometers are properly unbalanced, a strategy which can be straightforwardly applied to most of today's experiments based on energy-time and time-bin entanglement. Our scheme has therefore a great potential for boosting bit rates and reducing the resource overhead of future entanglement-based quantum key distribution systems.
Testing of Error-Correcting Sparse Permutation Channel Codes
NASA Technical Reports Server (NTRS)
Shcheglov, Kirill, V.; Orlov, Sergei S.
2008-01-01
A computer program performs Monte Carlo direct numerical simulations for testing sparse permutation channel codes, which offer strong error-correction capabilities at high code rates and are considered especially suitable for storage of digital data in holographic and volume memories. A word in a code of this type is characterized by, among other things, a sparseness parameter (M) and a fixed number (K) of 1 or "on" bits in a channel block length of N.
Use of single-cutter data in the analysis of PDC bit designs
Glowka, D.A.
1986-10-10
A method is developed for predicting cutter forces, temperatures, and wear on PDC bits as well as integrated bit performance parameters such as weight-on-bit (WOB), drilling torque, and bit imbalance. A computer code called PDCWEAR has been developed to make this method available as a tool for general bit design. The method uses single-cutter data to provide a measure of rock drillability and employs theoretical considerations to account for interaction among closely spaced cutters on the bit. Experimental data are presented to establish the effects of cutter size and wearflat area on the forces that develop during rock cutting. Waterjet assistance is shown to significantly reduce cutting forces, thereby extending bit life and reducing WOB and torque requirements in hard rock. The effects of bit profile, cutter placement density, bit rotary speed, and wear mode on bit life and drilling performance are investigated. 21 refs., 34 figs., 4 tabs.
A low cost alternative to high performance PCM bit synchronizers
NASA Technical Reports Server (NTRS)
Deshong, Bruce
1993-01-01
The Code Converter/Clock Regenerator (CCCR) provides a low-cost alternative to high-performance Pulse Code Modulation (PCM) bit synchronizers in environments with a large Signal-to-Noise Ratio (SNR). In many applications, the CCCR can be used in place of PCM bit synchronizers at about one fifth the cost. The CCCR operates at rates from 10 bps to 2.5 Mbps and performs PCM code conversion and clock regeneration. The CCCR has been integrated into a stand-alone system configurable from one to six channels and has also been designed for use in VMEbus compatible systems.
Foldable Instrumented Bits for Ultrasonic/Sonic Penetrators
NASA Technical Reports Server (NTRS)
Bar-Cohen, Yoseph; Badescu, Mircea; Iskenderian, Theodore; Sherrit, Stewart; Bao, Xiaoqi; Linderman, Randel
2010-01-01
Long tool bits are undergoing development that can be stowed compactly until used as rock- or ground-penetrating probes actuated by ultrasonic/sonic mechanisms. These bits are designed to be folded or rolled into compact form for transport to exploration sites, where they are to be connected to their ultrasonic/ sonic actuation mechanisms and unfolded or unrolled to their full lengths for penetrating ground or rock to relatively large depths. These bits can be designed to acquire rock or soil samples and/or to be equipped with sensors for measuring properties of rock or soil in situ. These bits can also be designed to be withdrawn from the ground, restowed, and transported for reuse at different exploration sites. Apparatuses based on the concept of a probe actuated by an ultrasonic/sonic mechanism have been described in numerous prior NASA Tech Briefs articles, the most recent and relevant being "Ultrasonic/ Sonic Impacting Penetrators" (NPO-41666) NASA Tech Briefs, Vol. 32, No. 4 (April 2008), page 58. All of those apparatuses are variations on the basic theme of the earliest ones, denoted ultrasonic/sonic drill corers (USDCs). To recapitulate: An apparatus of this type includes a lightweight, low-power, piezoelectrically driven actuator in which ultrasonic and sonic vibrations are generated and coupled to a tool bit. The combination of ultrasonic and sonic vibrations gives rise to a hammering action (and a resulting chiseling action at the tip of the tool bit) that is more effective for drilling than is the microhammering action of ultrasonic vibrations alone. The hammering and chiseling actions are so effective that the size of the axial force needed to make the tool bit advance into soil, rock, or another material of interest is much smaller than in ordinary twist drilling, ordinary hammering, or ordinary steady pushing. Examples of properties that could be measured by use of an instrumented tool bit include electrical conductivity, permittivity, magnetic
Synthesis and evaluation of phase detectors for active bit synchronizers
NASA Technical Reports Server (NTRS)
Mcbride, A. L.
1974-01-01
Self-synchronizing digital data communication systems usually use active or phase-locked loop (PLL) bit synchronizers. The three main elements of PLL synchronizers are the phase detector, loop filter, and the voltage controlled oscillator. Of these three elements, phase detector synthesis is the main source of difficulty, particularly when the received signals are demodulated square-wave signals. A phase detector synthesis technique is reviewed that provides a physically realizable design for bit synchronizer phase detectors. The development is based upon nonlinear recursive estimation methods. The phase detector portion of the algorithm is isolated and analyzed.
Development of a jet-assisted polycrystalline diamond drill bit
Pixton, D.S.; Hall, D.R.; Summers, D.A.; Gertsch, R.E.
1997-12-31
A preliminary investigation has been conducted to evaluate the technical feasibility and potential economic benefits of a new type of drill bit. This bit transmits both rotary and percussive drilling forces to the rock face, and augments this cutting action with high-pressure mud jets. Both the percussive drilling forces and the mud jets are generated down-hole by a mud-actuated hammer. Initial laboratory studies show that rate of penetration increases on the order of a factor of two over unaugmented rotary and/or percussive drilling rates are possible with jet-assistance.
Hanford coring bit temperature monitor development testing results report
Rey, D.
1995-05-01
Instrumentation which directly monitors the temperature of a coring bit used to retrieve core samples of high level nuclear waste stored in tanks at Hanford was developed at Sandia National Laboratories. Monitoring the temperature of the coring bit is desired to enhance the safety of the coring operations. A unique application of mature technologies was used to accomplish the measurement. This report documents the results of development testing performed at Sandia to assure the instrumentation will withstand the severe environments present in the waste tanks.
Cloning the entanglement of a pair of quantum bits
Lamoureux, Louis-Philippe; Navez, Patrick; Cerf, Nicolas J.; Fiurasek, Jaromir
2004-04-01
It is shown that any quantum operation that perfectly clones the entanglement of all maximally entangled qubit pairs cannot preserve separability. This 'entanglement no-cloning' principle naturally suggests that some approximate cloning of entanglement is nevertheless allowed by quantum mechanics. We investigate a separability-preserving optimal cloning machine that duplicates all maximally entangled states of two qubits, resulting in 0.285 bits of entanglement per clone, while a local cloning machine only yields 0.060 bits of entanglement per clone.
Bit-wise arithmetic coding for data compression
NASA Technical Reports Server (NTRS)
Kiely, A. B.
1994-01-01
This article examines the problem of compressing a uniformly quantized independent and identically distributed (IID) source. We present a new compression technique, bit-wise arithmetic coding, that assigns fixed-length codewords to the quantizer output and uses arithmetic coding to compress the codewords, treating the codeword bits as independent. We examine the performance of this method and evaluate the overhead required when used block-adaptively. Simulation results are presented for Gaussian and Laplacian sources. This new technique could be used as the entropy coder in a transform or subband coding system.
Numerical Simulation of Coherent Error Correction
NASA Astrophysics Data System (ADS)
Crow, Daniel; Joynt, Robert; Saffman, Mark
A major goal in quantum computation is the implementation of error correction to produce a logical qubit with an error rate lower than that of the underlying physical qubits. Recent experimental progress demonstrates physical qubits can achieve error rates sufficiently low for error correction, particularly for codes with relatively high thresholds such as the surface code and color code. Motivated by experimental capabilities of neutral atom systems, we use numerical simulation to investigate whether coherent error correction can be effectively used with the 7-qubit color code. The results indicate that coherent error correction does not work at the 10-qubit level in neutral atom array quantum computers. By adding more qubits there is a possibility of making the encoding circuits fault-tolerant which could improve performance.
Low-bit rate feedback strategies for iterative IA-precoded MIMO-OFDM-based systems.
Teodoro, Sara; Silva, Adão; Dinis, Rui; Gameiro, Atílio
2014-01-01
Interference alignment (IA) is a promising technique that allows high-capacity gains in interference channels, but which requires the knowledge of the channel state information (CSI) for all the system links. We design low-complexity and low-bit rate feedback strategies where a quantized version of some CSI parameters is fed back from the user terminal (UT) to the base station (BS), which shares it with the other BSs through a limited-capacity backhaul network. This information is then used by BSs to perform the overall IA design. With the proposed strategies, we only need to send part of the CSI information, and this can even be sent only once for a set of data blocks transmitted over time-varying channels. These strategies are applied to iterative MMSE-based IA techniques for the downlink of broadband wireless OFDM systems with limited feedback. A new robust iterative IA technique, where channel quantization errors are taken into account in IA design, is also proposed and evaluated. With our proposed strategies, we need a small number of quantization bits to transmit and share the CSI, when comparing with the techniques used in previous works, while allowing performance close to the one obtained with perfect channel knowledge. PMID:24678274
Low bit rate video coding using robust motion vector regeneration in the decoder.
Banham, M R; Brailean, J C; Chan, C L; Katsaggelos, A K
1994-01-01
In this paper, we present a novel coding technique that makes use of the nonstationary characteristics of an image sequence displacement field to estimate and encode motion information. We utilize an MPEG style codec in which the anchor frames in a sequence are encoded with a hybrid approach using quadtree, DCT, and wavelet-based coding techniques. A quadtree structured approach is also utilized for the interframe information. The main objective of the overall design is to demonstrate the coding potential of a newly developed motion estimator called the coupled linearized MAP (CLMAP) estimator. This estimator can be used as a means for producing motion vectors that may be regenerated at the decoder with a coarsely quantized error term created in the encoder. The motion estimator generates highly accurate motion estimates from this coarsely quantized data. This permits the elimination of a separately coded displaced frame difference (DFD) and coded motion vectors. For low bit rate applications, this is especially important because the overhead associated with the transmission of motion vectors may become prohibitive. We exploit both the advantages of the nonstationary motion estimator and the effective compression of the anchor frame coder to improve the visual quality of reconstructed QCIF format color image sequences at low bit rates. Comparisons are made with other video coding methods, including the H.261 and MPEG standards and a pel-recursive-based codec. PMID:18291958
Low-Bit Rate Feedback Strategies for Iterative IA-Precoded MIMO-OFDM-Based Systems
Teodoro, Sara; Silva, Adão; Dinis, Rui; Gameiro, Atílio
2014-01-01
Interference alignment (IA) is a promising technique that allows high-capacity gains in interference channels, but which requires the knowledge of the channel state information (CSI) for all the system links. We design low-complexity and low-bit rate feedback strategies where a quantized version of some CSI parameters is fed back from the user terminal (UT) to the base station (BS), which shares it with the other BSs through a limited-capacity backhaul network. This information is then used by BSs to perform the overall IA design. With the proposed strategies, we only need to send part of the CSI information, and this can even be sent only once for a set of data blocks transmitted over time-varying channels. These strategies are applied to iterative MMSE-based IA techniques for the downlink of broadband wireless OFDM systems with limited feedback. A new robust iterative IA technique, where channel quantization errors are taken into account in IA design, is also proposed and evaluated. With our proposed strategies, we need a small number of quantization bits to transmit and share the CSI, when comparing with the techniques used in previous works, while allowing performance close to the one obtained with perfect channel knowledge. PMID:24678274
Wu, Xiaoxia; Wang, Jian; Yilmaz, Omer F; Nuccio, Scott R; Bogoni, Antonella; Willner, Alan E
2010-09-15
We experimentally demonstrate high-speed optical pseudorandom bit sequence (PRBS) multiplexing with coarse and fine bit-rate tuning capability and a switchable order using optical delays. Data multiplexing of 80 Gbit/s and 160 Gbit/s is shown, each with a tunable rate using a conversion/dispersion-based continuously tunable optical delay and tunable PRBS order with large switchable fiber delays. A 7% bit-rate tunability, i.e., 80-85.6 Gbit/s and 160-171.2 Gbit/s, is shown for both 2(7)-1 and 2(15)-1 PRBS. The rf spectra before and after multiplexing are measured in each case and show a suppression ratio of >30 dB, exhibiting the expected PRBS spectral characteristics. PMID:20847772
Refractive errors in children.
Tongue, A C
1987-12-01
Optical correction of refractive errors in infants and young children is indicated when the refractive errors are sufficiently large to cause unilateral or bilateral amblyopia, if they are impairing the child's ability to function normally, or if the child has accommodative strabismus. Screening for refractive errors is important and should be performed as part of the annual physical examination in all verbal children. Screening for significant refractive errors in preverbal children is more difficult; however, the red reflex test of Bruckner is useful for the detection of anisometropic refractive errors. The photorefraction test, which is an adaptation of Bruckner's red reflex test, may prove to be a useful screening device for detecting bilateral as well as unilateral refractive errors. Objective testing as well as subjective testing enables ophthalmologists to prescribe proper optical correction for refractive errors for infants and children of any age. PMID:3317238
Johnstone, R A; Grafen, A
1992-06-22
The handicap principle of Zahavi is potentially of great importance to the study of biological communication. Existing models of the handicap principle, however, make the unrealistic assumption that communication is error free. It seems possible, therefore, that Zahavi's arguments do not apply to real signalling systems, in which some degree of error is inevitable. Here, we present a general evolutionarily stable strategy (ESS) model of the handicap principle which incorporates perceptual error. We show that, for a wide range of error functions, error-prone signalling systems must be honest at equilibrium. Perceptual error is thus unlikely to threaten the validity of the handicap principle. Our model represents a step towards greater realism, and also opens up new possibilities for biological signalling theory. Concurrent displays, direct perception of quality, and the evolution of 'amplifiers' and 'attenuators' are all probable features of real signalling systems, yet handicap models based on the assumption of error-free communication cannot accommodate these possibilities. PMID:1354361
An efficient system for reliably transmitting image and video data over low bit rate noisy channels
NASA Technical Reports Server (NTRS)
Costello, Daniel J., Jr.; Huang, Y. F.; Stevenson, Robert L.
1994-01-01
This research project is intended to develop an efficient system for reliably transmitting image and video data over low bit rate noisy channels. The basic ideas behind the proposed approach are the following: employ statistical-based image modeling to facilitate pre- and post-processing and error detection, use spare redundancy that the source compression did not remove to add robustness, and implement coded modulation to improve bandwidth efficiency and noise rejection. Over the last six months, progress has been made on various aspects of the project. Through our studies of the integrated system, a list-based iterative Trellis decoder has been developed. The decoder accepts feedback from a post-processor which can detect channel errors in the reconstructed image. The error detection is based on the Huber Markov random field image model for the compressed image. The compression scheme used here is that of JPEG (Joint Photographic Experts Group). Experiments were performed and the results are quite encouraging. The principal ideas here are extendable to other compression techniques. In addition, research was also performed on unequal error protection channel coding, subband vector quantization as a means of source coding, and post processing for reducing coding artifacts. Our studies on unequal error protection (UEP) coding for image transmission focused on examining the properties of the UEP capabilities of convolutional codes. The investigation of subband vector quantization employed a wavelet transform with special emphasis on exploiting interband redundancy. The outcome of this investigation included the development of three algorithms for subband vector quantization. The reduction of transform coding artifacts was studied with the aid of a non-Gaussian Markov random field model. This results in improved image decompression. These studies are summarized and the technical papers included in the appendices.
Aircraft system modeling error and control error
NASA Technical Reports Server (NTRS)
Kulkarni, Nilesh V. (Inventor); Kaneshige, John T. (Inventor); Krishnakumar, Kalmanje S. (Inventor); Burken, John J. (Inventor)
2012-01-01
A method for modeling error-driven adaptive control of an aircraft. Normal aircraft plant dynamics is modeled, using an original plant description in which a controller responds to a tracking error e(k) to drive the component to a normal reference value according to an asymptote curve. Where the system senses that (1) at least one aircraft plant component is experiencing an excursion and (2) the return of this component value toward its reference value is not proceeding according to the expected controller characteristics, neural network (NN) modeling of aircraft plant operation may be changed. However, if (1) is satisfied but the error component is returning toward its reference value according to expected controller characteristics, the NN will continue to model operation of the aircraft plant according to an original description.
Balancing the Lifetime and Storage Overhead on Error Correction for Phase Change Memory
An, Ning; Wang, Rui; Gao, Yuan; Yang, Hailong; Qian, Depei
2015-01-01
As DRAM is facing the scaling difficulty in terms of energy cost and reliability, some nonvolatile storage materials were proposed to be the substitute or supplement of main memory. Phase Change Memory (PCM) is one of the most promising nonvolatile memory that could be put into use in the near future. However, before becoming a qualified main memory technology, PCM should be designed reliably so that it can ensure the computer system’s stable running even when errors occur. The typical wear-out errors in PCM have been well studied, but the transient errors, that caused by high-energy particles striking on the complementary metal-oxide semiconductor (CMOS) circuit of PCM chips or by resistance drifting in multi-level cell PCM, have attracted little focus. In this paper, we propose an innovative mechanism, Local-ECC-Global-ECPs (LEGE), which addresses both soft errors and hard errors (wear-out errors) in PCM memory systems. Our idea is to deploy a local error correction code (ECC) section to every data line, which can detect and correct one-bit errors immediately, and a global error correction pointers (ECPs) buffer for the whole memory chip, which can be reloaded to correct more hard error bits. The local ECC is used to detect and correct the unknown one-bit errors, and the global ECPs buffer is used to store the corrected value of hard errors. In comparison to ECP-6, our method provides almost identical lifetimes, but reduces approximately 50% storage overhead. Moreover, our structure reduces approximately 3.55% access latency overhead by increasing 1.61% storage overhead compared to PAYG, a hard error only solution. PMID:26158524
A radiation-hardened 16/32-bit microprocessor
Hass, K.J.; Treece, R.K.; Giddings, A.E.
1989-01-01
A radiation-hardened 16/32-bit microprocessor has been fabricated and tested. Our initial evaluation has demonstrated that it is functional after a total gamma dose of 5Mrad(Si) and is immune to SEU from Krypton ions. 3 refs., 2 figs.
Characterization of a 16-Bit Digitizer for Lidar Data Acquisition
NASA Technical Reports Server (NTRS)
Williamson, Cynthia K.; DeYoung, Russell J.
2000-01-01
A 6-MHz 16-bit waveform digitizer was evaluated for use in atmospheric differential absorption lidar (DIAL) measurements of ozone. The digitizer noise characteristics were evaluated, and actual ozone DIAL atmospheric returns were digitized. This digitizer could replace computer-automated measurement and control (CAMAC)-based commercial digitizers and improve voltage accuracy.
Rock bit requires no flushing medium to maintain drilling speed
NASA Technical Reports Server (NTRS)
1965-01-01
Steel drill bit having terraces of teeth intersected by spiral grooves with teeth permits the boring of small holes through rock with low power. The cuttings are stored in a chamber behind the cutting head. Could be used as sampling device.
Optimization Approaches for Designing a Novel 4-Bit Reversible Comparator
NASA Astrophysics Data System (ADS)
Zhou, Ri-gui; Zhang, Man-qun; Wu, Qian; Li, Yan-cheng
2013-02-01
Reversible logic is a new rapidly developed research field in recent years, which has been receiving much attention for calculating with minimizing the energy consumption. This paper constructs a 4×4 new reversible gate called ZRQ gate to build quantum adder and subtraction. Meanwhile, a novel 1-bit reversible comparator by using the proposed ZRQC module on the basis of ZRQ gate is proposed as the minimum number of reversible gates and quantum costs. In addition, this paper presents a novel 4-bit reversible comparator based on the 1-bit reversible comparator. One of the vital important for optimizing reversible logic is to design reversible logic circuits with the minimum number of parameters. The proposed reversible comparators in this paper can obtain superiority in terms of the number of reversible gates, input constants, garbage outputs, unit delays and quantum costs compared with the existed circuits. Finally, MATLAB simulation software is used to test and verify the correctness of the proposed 4-bit reversible comparator.
16. STRUCTURAL DETAILS: CHANNEL, BIT & CLEAT, ANCHOR BOLTS & ...
16. STRUCTURAL DETAILS: CHANNEL, BIT & CLEAT, ANCHOR BOLTS & PLATES FOR PIERS 4, 5, AND 6, DWG. NO. 97, 1-1/2" = 1', MADE BY A.F., JUNE 13, 1908 - Baltimore Inner Harbor, Pier 5, South of Pratt Street between Market Place & Concord Street, Baltimore, Independent City, MD
Nonanalytic function generation routines for 16-bit microprocessors
NASA Technical Reports Server (NTRS)
Soeder, J. F.; Shaufl, M.
1980-01-01
Interpolation techniques for three types (univariate, bivariate, and map) of nonanalytic functions are described. These interpolation techniques are then implemented in scaled fraction arithmetic on a representative 16 bit microprocessor. A FORTRAN program is described that facilitates the scaling, documentation, and organization of data for use by these routines. Listings of all these programs are included in an appendix.
Multi-bit operations in vertical spintronic shift registers
NASA Astrophysics Data System (ADS)
Lavrijsen, Reinoud; Petit, Dorothée C. M. C.; Fernández-Pacheco, Amalio; Lee, JiHyun; Mansell, Mansell; Cowburn, Russell P.
2014-03-01
Spintronic devices have in general demonstrated the feasibility of non-volatile memory storage and simple Boolean logic operations. Modern microprocessors have one further frequently used digital operation: bit-wise operations on multiple bits simultaneously. Such operations are important for binary multiplication and division and in efficient microprocessor architectures such as reduced instruction set computing (RISC). In this paper we show a four-stage vertical serial shift register made from RKKY coupled ultrathin (0.9 nm) perpendicularly magnetised layers into which a 3-bit data word is injected. The entire four stage shift register occupies a total length (thickness) of only 16 nm. We show how under the action of an externally applied magnetic field bits can be shifted together as a word and then manipulated individually, including being brought together to perform logic operations. This is one of the highest level demonstrations of logic operation ever performed on data in the magnetic state and brings closer the possibility of ultrahigh density all-magnetic microprocessors.
Olama, Mohammed M; Matalgah, Mustafa M; Bobrek, Miljko
2015-01-01
Traditional encryption techniques require packet overhead, produce processing time delay, and suffer from severe quality of service deterioration due to fades and interference in wireless channels. These issues reduce the effective transmission data rate (throughput) considerably in wireless communications, where data rate with limited bandwidth is the main constraint. In this paper, performance evaluation analyses are conducted for an integrated signaling-encryption mechanism that is secure and enables improved throughput and probability of bit-error in wireless channels. This mechanism eliminates the drawbacks stated herein by encrypting only a small portion of an entire transmitted frame, while the rest is not subject to traditional encryption but goes through a signaling process (designed transformation) with the plaintext of the portion selected for encryption. We also propose to incorporate error correction coding solely on the small encrypted portion of the data to drastically improve the overall bit-error rate performance while not noticeably increasing the required bit-rate. We focus on validating the signaling-encryption mechanism utilizing Hamming and convolutional error correction coding by conducting an end-to-end system-level simulation-based study. The average probability of bit-error and throughput of the encryption mechanism are evaluated over standard Gaussian and Rayleigh fading-type channels and compared to the ones of the conventional advanced encryption standard (AES).
10-bit 20-Msample/s ADC for low-voltage low-power applications
NASA Astrophysics Data System (ADS)
Sou, Gerard; Lu, Guo N.; Klisnick, Geoffroy; Redon, Michel
1998-09-01
For the development of new low-voltage, low-power imaging microsystems, we have designed a 10-bit 20-Msample/s ADC. It is a 3-stage sub-ranging architecture and has a rail-to-rail dynamic input. To achieve low-voltage operation and low- power consumption, specific analog blocks such as op-amps and flash ADCs were required. Complementary CMOS comparators with no static consumption were used to build a new low- power 4-bit flash ADC structure with rail-to-rail input range. A new 1.7 volts, 120 dB op-amp structure was designed. To achieve 20 MHz sampling rate, the ADC makes use of time-interleaving, switched capacitor amplifiers, which perform dynamic frequency compensation to optimize speed and offset cancellation to meet resolution requirement. A 20- Msample/s rate has been obtained with supply voltages down to 2.4 volts to 2.4 volts and 60mW power consumption. This ADC has been fabricated and tested and will be integrated on the same chip with color image sensors in a BICMOS process.
Estimating Hardness from the USDC Tool-Bit Temperature Rise
NASA Technical Reports Server (NTRS)
Bar-Cohen, Yoseph; Sherrit, Stewart
2008-01-01
A method of real-time quantification of the hardness of a rock or similar material involves measurement of the temperature, as a function of time, of the tool bit of an ultrasonic/sonic drill corer (USDC) that is being used to drill into the material. The method is based on the idea that, other things being about equal, the rate of rise of temperature and the maximum temperature reached during drilling increase with the hardness of the drilled material. In this method, the temperature is measured by means of a thermocouple embedded in the USDC tool bit near the drilling tip. The hardness of the drilled material can then be determined through correlation of the temperature-rise-versus-time data with time-dependent temperature rises determined in finite-element simulations of, and/or experiments on, drilling at various known rates of advance or known power levels through materials of known hardness. The figure presents an example of empirical temperature-versus-time data for a particular 3.6-mm USDC bit, driven at an average power somewhat below 40 W, drilling through materials of various hardness levels. The temperature readings from within a USDC tool bit can also be used for purposes other than estimating the hardness of the drilled material. For example, they can be especially useful as feedback to control the driving power to prevent thermal damage to the drilled material, the drill bit, or both. In the case of drilling through ice, the temperature readings could be used as a guide to maintaining sufficient drive power to prevent jamming of the drill by preventing refreezing of melted ice in contact with the drill.
Numerical study of the simplest string bit model
NASA Astrophysics Data System (ADS)
Chen, Gaoli; Sun, Songge
2016-05-01
String bit models provide a possible method to formulate a string as a discrete chain of pointlike string bits. When the bit number M is large, a chain behaves as a continuous string. We study the simplest case that has only one bosonic bit and one fermionic bit. The creation and annihilation operators are adjoint representations of the U (N ) color group. We show that the supersymmetry reduces the parameter number of a Hamiltonian from 7 to 3 and, at N =∞ , ensures a continuous energy spectrum, which implies the emergence of one spatial dimension. The Hamiltonian H0 is constructed so that in the large N limit it produces a world sheet spectrum with one Grassmann world sheet field. We concentrate on the numerical study of the model in finite N . For the Hamiltonian H0, we find that the would-be ground energy states disappear at N =(M -1 ) /2 for odd M ≤11 . Such a simple pattern is spoiled if H has an additional term ξ Δ H which does not affect the result of N =∞ . The disappearance point moves to higher (lower) N when ξ increases (decreases). Particularly, the ±(H0-Δ H ) cases suggest a possibility that the ground state could survive at large M and M ≫N . Our study reveals that the model has stringy behavior: when N is fixed and large enough, the ground energy decreases linearly with respect to M , and the excitation energy is roughly of order M-1. We also verify that a stable system of Hamiltonian ±H0+ξ Δ H requires ξ ≥∓1 .
NASA Astrophysics Data System (ADS)
Macuda, Jan
2012-11-01
In Poland all lignite mines are dewatered with the use of large-diameter wells. Drilling of such wells is inefficient owing to the presence of loose Quaternary and Tertiary material and considerable dewatering of rock mass within the open pit area. Difficult geological conditions significantly elongate the time in which large-diameter dewatering wells are drilled, and various drilling complications and break-downs related to the caving may occur. Obtaining higher drilling rates in large-diameter wells can be achieved only when new cutter bits designs are worked out and rock drillability tests performed for optimum mechanical parameters of drilling technology. Those tests were performed for a bit ø 1.16 m in separated macroscopically homogeneous layers of similar drillability. Depending on the designed thickness of the drilled layer, there were determined measurement sections from 0.2 to 1.0 m long, and each of the sections was drilled at constant rotary speed and weight on bit values. Prior to drillability tests, accounting for the technical characteristic of the rig and strength of the string and the cutter bit, there were established limitations for mechanical parameters of drilling technology: P ∈ (Pmin; Pmax) n ∈ (nmin; nmax) where: Pmin; Pmax - lowest and highest values of weight on bit, nmin; nmax - lowest and highest values of rotary speed of bit, For finding the dependence of the rate of penetration on weight on bit and rotary speed of bit various regression models have been analyzed. The most satisfactory results were obtained for the exponential model illustrating the influence of weight on bit and rotary speed of bit on drilling rate. The regression coefficients and statistical parameters prove the good fit of the model to measurement data, presented in tables 4-6. The average drilling rate for a cutter bit with profiled wings has been described with the form: Vśr= Z ·Pa· nb where: Vśr- average drilling rate, Z - drillability coefficient, P
Cheat-sensitive commitment of a classical bit coded in a block of m × n round-trip qubits
NASA Astrophysics Data System (ADS)
Shimizu, Kaoru; Fukasaka, Hiroyuki; Tamaki, Kiyoshi; Imoto, Nobuyuki
2011-08-01
This paper proposes a quantum protocol for a cheat-sensitive commitment of a classical bit. Alice, the receiver of the bit, can examine dishonest Bob, who changes or postpones his choice. Bob, the sender of the bit, can examine dishonest Alice, who violates concealment. For each round-trip case, Alice sends one of two spin states |S±⟩ by choosing basis S at random from two conjugate bases X and Y. Bob chooses basis C ∈ {X,Y} to perform a measurement and returns a resultant state |C±⟩. Alice then performs a measurement with the other basis R (≠S) and obtains an outcome |R±⟩. In the opening phase, she can discover dishonest Bob, who unveils a wrong basis with a faked spin state, or Bob can discover dishonest Alice, who infers basis C but destroys |C±⟩ by setting R to be identical to S in the commitment phase. If a classical bit is coded in a block of m × n qubit particles, impartial examinations and probabilistic security criteria can be achieved.
Cheat-sensitive commitment of a classical bit coded in a block of mxn round-trip qubits
Shimizu, Kaoru; Fukasaka, Hiroyuki; Tamaki, Kiyoshi; Imoto, Nobuyuki
2011-08-15
This paper proposes a quantum protocol for a cheat-sensitive commitment of a classical bit. Alice, the receiver of the bit, can examine dishonest Bob, who changes or postpones his choice. Bob, the sender of the bit, can examine dishonest Alice, who violates concealment. For each round-trip case, Alice sends one of two spin states |S{+-}> by choosing basis S at random from two conjugate bases X and Y. Bob chooses basis C is an element of {l_brace}X,Y{r_brace} to perform a measurement and returns a resultant state |C{+-}>. Alice then performs a measurement with the other basis R ({ne}S) and obtains an outcome |R{+-}>. In the opening phase, she can discover dishonest Bob, who unveils a wrong basis with a faked spin state, or Bob can discover dishonest Alice, who infers basis C but destroys |C{+-}> by setting R to be identical to S in the commitment phase. If a classical bit is coded in a block of mxn qubit particles, impartial examinations and probabilistic security criteria can be achieved.
On the undetected error probability of a concatenated coding scheme for error control
NASA Technical Reports Server (NTRS)
Deng, H.; Costello, D. J., Jr.
1984-01-01
Consider a concatenated coding scheme for error control on a binary symmetric channel, called the inner channel. The bit error rate (BER) of the channel is correspondingly called the inner BER, and is denoted by Epsilon (sub i). Two linear block codes, C(sub f) and C(sub b), are used. The inner code C(sub f), called the frame code, is an (n,k) systematic binary block code with minimum distance, d(sub f). The frame code is designed to correct + or fewer errors and simultaneously detect gamma (gamma +) or fewer errors, where + + gamma + 1 = to or d(sub f). The outer code C(sub b) is either an (n(sub b), K(sub b)) binary block with a n(sub b) = mk, or an (n(sub b), k(Sub b) maximum distance separable (MDS) code with symbols from GF(q), where q = 2(b) and the code length n(sub b) satisfies n(sub)(b) = mk. The integerim is the number of frames. The outercode is designed for error detection only.
Olson, Eric J.
2013-06-11
An apparatus, program product, and method that run an algorithm on a hardware based processor, generate a hardware error as a result of running the algorithm, generate an algorithm output for the algorithm, compare the algorithm output to another output for the algorithm, and detect the hardware error from the comparison. The algorithm is designed to cause the hardware based processor to heat to a degree that increases the likelihood of hardware errors to manifest, and the hardware error is observable in the algorithm output. As such, electronic components may be sufficiently heated and/or sufficiently stressed to create better conditions for generating hardware errors, and the output of the algorithm may be compared at the end of the run to detect a hardware error that occurred anywhere during the run that may otherwise not be detected by traditional methodologies (e.g., due to cooling, insufficient heat and/or stress, etc.).
The Error in Total Error Reduction
Witnauer, James E.; Urcelay, Gonzalo P.; Miller, Ralph R.
2013-01-01
Most models of human and animal learning assume that learning is proportional to the discrepancy between a delivered outcome and the outcome predicted by all cues present during that trial (i.e., total error across a stimulus compound). This total error reduction (TER) view has been implemented in connectionist and artificial neural network models to describe the conditions under which weights between units change. Electrophysiological work has revealed that the activity of dopamine neurons is correlated with the total error signal in models of reward learning. Similar neural mechanisms presumably support fear conditioning, human contingency learning, and other types of learning. Using a computational modelling approach, we compared several TER models of associative learning to an alternative model that rejects the TER assumption in favor of local error reduction (LER), which assumes that learning about each cue is proportional to the discrepancy between the delivered outcome and the outcome predicted by that specific cue on that trial. The LER model provided a better fit to the reviewed data than the TER models. Given the superiority of the LER model with the present data sets, acceptance of TER should be tempered. PMID:23891930
NASA Technical Reports Server (NTRS)
Briggs, Hugh C.
2008-01-01
An error budget is a commonly used tool in design of complex aerospace systems. It represents system performance requirements in terms of allowable errors and flows these down through a hierarchical structure to lower assemblies and components. The requirements may simply be 'allocated' based upon heuristics or experience, or they may be designed through use of physics-based models. This paper presents a basis for developing an error budget for models of the system, as opposed to the system itself. The need for model error budgets arises when system models are a principle design agent as is increasingly more common for poorly testable high performance space systems.
An improved pi/4-QPSK with nonredundant error correction for satellite mobile broadcasting
NASA Technical Reports Server (NTRS)
Feher, Kamilo; Yang, Jiashi
1991-01-01
An improved pi/4-quadrature phase-shift keying (QPSK) receiver that incorporates a simple nonredundant error correction (NEC) structure is proposed for satellite and land-mobile digital broadcasting. The bit-error-rate (BER) performance of the pi/4-QPSK with NEC is analyzed and evaluated in a fast Rician fading and additive white Gaussian noise (AWGN) environment using computer simulation. It is demonstrated that with simple electronics the performance of a noncoherently detected pi/4-QPSK signal in both AWGN and fast Rician fading can be improved. When the K-factor (a ratio of average power of multipath signal to direct path power) of the Rician channel decreases, the improvement increases. An improvement of 1.2 dB could be obtained at a BER of 0.0001 in the AWGN channel. This performance gain is achieved without requiring any signal redundancy and additional bandwidth. Three types of noncoherent detection schemes of pi/4-QPSK with NEC structure, such as IF band differential detection, baseband differential detection, and FM discriminator, are discussed. It is concluded that the pi/4-QPSK with NEC is an attractive scheme for power-limited satellite land-mobile broadcasting systems.
Repeated quantum error correction on a continuously encoded qubit by real-time feedback
NASA Astrophysics Data System (ADS)
Cramer, J.; Kalb, N.; Rol, M. A.; Hensen, B.; Blok, M. S.; Markham, M.; Twitchen, D. J.; Hanson, R.; Taminiau, T. H.
2016-05-01
Reliable quantum information processing in the face of errors is a major fundamental and technological challenge. Quantum error correction protects quantum states by encoding a logical quantum bit (qubit) in multiple physical qubits. To be compatible with universal fault-tolerant computations, it is essential that states remain encoded at all times and that errors are actively corrected. Here we demonstrate such active error correction on a continuously protected logical qubit using a diamond quantum processor. We encode the logical qubit in three long-lived nuclear spins, repeatedly detect phase errors by non-destructive measurements, and apply corrections by real-time feedback. The actively error-corrected qubit is robust against errors and encoded quantum superposition states are preserved beyond the natural dephasing time of the best physical qubit in the encoding. These results establish a powerful platform to investigate error correction under different types of noise and mark an important step towards fault-tolerant quantum information processing.
A real-time bit-serial rank filter implementation using Xilinx FPGA
NASA Astrophysics Data System (ADS)
Choo, Chang; Verma, Punam
2008-02-01
Rank filter is a non-linear filter used in image processing for impulse noise removal, morphological operations, and image enhancement. Real-time applications, such as video and high-speed acquisition cameras, often require the rank filter, and the much simpler median filter. Implementing the rank filter in hardware, can achieve the required speeds for these applications. Bit-serial algorithm can increase the speed of rank filter by eliminating the time-consuming sorting network. In this paper, an 8-stage pipelined architecture for rank filter is described using the bit-serial algorithm. It also includes an efficient window extraction and boundary-processing scheme. This rank filter design was simulated and synthesized on the Xilinx family of FPGAs. For 3×3 window size, the maximum operating frequency achieved was 75 MHz on a low-end device XC3S200 of Spartan-3 family, and 180 MHz on a high-end device XC4VSX25 of Virtex-4 family. For 5×5 window size, the maximum operating frequency achieved was 67 MHz on XC3S200, and 138 MHz on XC4VSX25. With a pixel filtered out at every clock cycle, the achieved speeds are sufficient for most of the video applications. The 3×3 window size design used 31% of slices on XC3S200, and 5% on XC4VSX25. The 5×5 window size design used 60% of slices on XC3S200, and 11% on XC4VSX25. This IP design may be used as a hardware accelerator in a fast image processing SOC.
NASA Astrophysics Data System (ADS)
El-Shafai, Walid
2015-09-01
3D multi-view video (MVV) is multiple video streams shot by several cameras around a single scene simultaneously. Therefore it is an urgent task to achieve high 3D MVV compression to meet future bandwidth constraints while maintaining a high reception quality. 3D MVV coded bit-streams that are transmitted over wireless network can suffer from error propagation in the space, time and view domains. Error concealment (EC) algorithms have the advantage of improving the received 3D video quality without any modifications in the transmission rate or in the encoder hardware or software. To improve the quality of reconstructed 3D MVV, we propose an efficient adaptive EC algorithm with multi-hypothesis modes to conceal the erroneous Macro-Blocks (MBs) of intra-coded and inter-coded frames by exploiting the spatial, temporal and inter-view correlations between frames and views. Our proposed algorithm adapts to 3D MVV motion features and to the error locations. The lost MBs are optimally recovered by utilizing motion and disparity matching between frames and views on pixel-by-pixel matching basis. Our simulation results show that the proposed adaptive multi-hypothesis EC algorithm can significantly improve the objective and subjective 3D MVV quality.
NASA Technical Reports Server (NTRS)
Mebratu, Derssie; Kegege, Obadiah; Shaw, Harry
2016-01-01
Digital signal transmits via a carrier wave, demodulates at a receiver and locates an ideal constellation position. However, a noise distortion, carrier leakage and phase noise divert an actual constellation position of a signal and locate to a new position. In order to assess a source of noise and carrier leakage, Bit Error Rate (BER) measurement technique is also used to evaluate the number of erroneous bit per bit transmitted signal. In addition, we present, Error Vector Magnitude (EVM), which measures an ideal and a new position, assesses a source of signal distortion, and evaluates a wireless communication system's performance with a single metric. Applying EVM technique, we also measure the performance of a User Services Subsystem Component Replacement (USSCR) modem. Furthermore, we propose EVM measurement technique in the Tracking and Data Relay Satellite system (TDRS) to measure and evaluate a channel impairment between a ground (transmitter) and the terminal (receiver) at White Sands Complex.
ERIC Educational Resources Information Center
Ware, Elizabeth A.; Uttal, David H.; DeLoache, Judy S.
2010-01-01
Young children occasionally make "scale errors"--they attempt to fit their bodies into extremely small objects or attempt to fit a larger object into another, tiny, object. For example, a child might try to sit in a dollhouse-sized chair or try to stuff a large doll into it. Scale error research was originally motivated by parents' and…
White, Andrew A; Gallagher, Thomas H
2013-01-01
Errors occur commonly in healthcare and can cause significant harm to patients. Most errors arise from a combination of individual, system, and communication failures. Neurologists may be involved in harmful errors in any practice setting and should familiarize themselves with tools to prevent, report, and examine errors. Although physicians, patients, and ethicists endorse candid disclosure of harmful medical errors to patients, many physicians express uncertainty about how to approach these conversations. A growing body of research indicates physicians often fail to meet patient expectations for timely and open disclosure. Patients desire information about the error, an apology, and a plan for preventing recurrence of the error. To meet these expectations, physicians should participate in event investigations and plan thoroughly for each disclosure conversation, preferably with a disclosure coach. Physicians should also anticipate and attend to the ongoing medical and emotional needs of the patient. A cultural change towards greater transparency following medical errors is in motion. Substantial progress is still required, but neurologists can further this movement by promoting policies and environments conducive to open reporting, respectful disclosure to patients, and support for the healthcare workers involved. PMID:24182370
Error-resilient performance evaluation of MPEG-4 and H.264
NASA Astrophysics Data System (ADS)
Jung, Bongsoo; Hwang, Young Hooi; Jeon, Byeungwoo; Kim, Myung Don; Choi, Song-In
2003-06-01
Recent advances in video coding technology have resulted in rapid growth of application in mobile communication. With this explosive growth, reliable transmission and error resilient technique become increasingly necessary to offer high quality multimedia service. This paper discusses the error resilient performances of the MPEG-4 simple profile under the H.324/M and the H.264 baseline under the IP packet networks. MPEG-4 simple profile has error resilient tools such as resynchronization marker insertion, data partitioning, and reversible VLC. H.264 baseline has the flexible macroblock ordering scheme, and others. The objective and subjective quality of decoded video is measured under various random bit and burst error conditions.
Quality Improvement Method using Double Error Correction in Burst Transmission Systems
NASA Astrophysics Data System (ADS)
Tsuchiya, Naosuke; Tomiyama, Shigenori; Tanaka, Kimio
Recently, it has a tendency to reduce an error correction and flow control in order to realize a high speed transmission in a burst transmission systems such as ATM network, IP (Internet Protocol) network, frame relay and so on. Therefore a degradation of network quality, an information loss caused by buffer overflow and decrease of average bit error rate, are occurred, especially for high speed information such as high definition television signals, it is necessary to improve these degradations. This paper proposes one of the typical reconstruction methods of lost information and an improvement of average bit error rate. In order to analyse the degradation phenomena, the Gilbert model is introduced for burst errors and the Fluid flow model for buffer overflow. This method is applied to ATM network which mainly transmit a video signals and it makes clear that proposed method is useful for high speed transmission.
Unequal error correction strategy for magnetic recording systems with multi-track processing
NASA Astrophysics Data System (ADS)
Myint, L. M. M.; Supnithi, P.
2012-04-01
In multi-track detection, the simultaneous recovery of user data of all tracks is obtained from multi-head or single-head reader with buffer. Due to incomplete inter-track interference (ITI) information of the outer tracks, unequal error rates exist among tracks. For a system with three-track processing, the center track exhibits a better performance than the others. In this work, we propose the unequal error protection (UEP) schemes to improve the overall system performance of a 2-D interference bit-patterned recording system with multi-track detection. The performances of the proposed schemes are investigated for the BPM channels with and without the media noise. Based on the simulation results, the proposed schemes offer the gain of about 0.2-0.3 dB over the equal error protection (EEP) scheme at a bit error rate of 10-4.
Soft Error Vulnerability of Iterative Linear Algebra Methods
Bronevetsky, G; de Supinski, B
2007-12-15
Devices become increasingly vulnerable to soft errors as their feature sizes shrink. Previously, soft errors primarily caused problems for space and high-atmospheric computing applications. Modern architectures now use features so small at sufficiently low voltages that soft errors are becoming significant even at terrestrial altitudes. The soft error vulnerability of iterative linear algebra methods, which many scientific applications use, is a critical aspect of the overall application vulnerability. These methods are often considered invulnerable to many soft errors because they converge from an imprecise solution to a precise one. However, we show that iterative methods can be vulnerable to soft errors, with a high rate of silent data corruptions. We quantify this vulnerability, with algorithms generating up to 8.5% erroneous results when subjected to a single bit-flip. Further, we show that detecting soft errors in an iterative method depends on its detailed convergence properties and requires more complex mechanisms than simply checking the residual. Finally, we explore inexpensive techniques to tolerate soft errors in these methods.
Earth boring bit with improved rigid face seal assembly
Burr, B.H.
1987-05-19
An earth boring bit is described with an improved pressure compensating face seal assembly having one rigid ring and sealing face carried by a bearing shaft and an opposed sealing face carried by the cutter. The bit comprises: a body; a cantilevered bearing shaft having a generally cylindrical journal bearing and positioned to extend obliquely inwardly and downwardly from the body; a cutter having a generally cylindrical bearing formed internally therein, secured for rotation about the journal bearing of the shaft; a lubrication system in the body, including a hydrostatic pressure compensator to lubricate the bearings; and a cutter seal groove formed near the outermost region of the cylindrical bearing in the cutter to have a circumferential, generally cylindrical wall.
A 128K-bit CCD buffer memory system
NASA Technical Reports Server (NTRS)
Siemens, K. H.; Wallace, R. W.; Robinson, C. R.
1976-01-01
A prototype system was implemented to demonstrate that CCD's can be applied advantageously to the problem of low power digital storage and particularly to the problem of interfacing widely varying data rates. 8K-bit CCD shift register memories were used to construct a feasibility model 128K-bit buffer memory system. Peak power dissipation during a data transfer is less than 7 W., while idle power is approximately 5.4 W. The system features automatic data input synchronization with the recirculating CCD memory block start address. Descriptions are provided of both the buffer memory system and a custom tester that was used to exercise the memory. The testing procedures and testing results are discussed. Suggestions are provided for further development with regards to the utilization of advanced versions of CCD memory devices to both simplified and expanded memory system applications.
Pack carburizing process for earth boring drill bits
Simons, R.W.; Scott, D.E.; Poland, J.R.
1987-02-17
A method is described of manufacturing an earth boring drill bit of the type having a bearing pin extending from a head section of the drill bit for rotatably mounting a cutter, comprising the steps of: providing a container having opposing end openings with sidewalls therebetween which define a container interior; placing the container over a portion of the head section so that the pin extends within the interior of the container; installing a spring spacer within the interior of the container about at least a portion of the circumference of the bearing pin at least one axial location; packing the container with a particulate treating medium; covering the container; and placing the pin and container into a furnace for a time and at a temperature to activate the treating medium.
Efficient biased random bit generation for parallel processing
Slone, D.M.
1994-09-28
A lattice gas automaton was implemented on a massively parallel machine (the BBN TC2000) and a vector supercomputer (the CRAY C90). The automaton models Burgers equation {rho}t + {rho}{rho}{sub x} = {nu}{rho}{sub xx} in 1 dimension. The lattice gas evolves by advecting and colliding pseudo-particles on a 1-dimensional, periodic grid. The specific rules for colliding particles are stochastic in nature and require the generation of many billions of random numbers to create the random bits necessary for the lattice gas. The goal of the thesis was to speed up the process of generating the random bits and thereby lessen the computational bottleneck of the automaton.
Fully Distrustful Quantum Bit Commitment and Coin Flipping
NASA Astrophysics Data System (ADS)
Silman, J.; Chailloux, A.; Aharon, N.; Kerenidis, I.; Pironio, S.; Massar, S.
2011-06-01
In the distrustful quantum cryptography model the parties have conflicting interests and do not trust one another. Nevertheless, they trust the quantum devices in their labs. The aim of the device-independent approach to cryptography is to do away with the latter assumption, and, consequently, significantly increase security. It is an open question whether the scope of this approach also extends to protocols in the distrustful cryptography model, thereby rendering them “fully” distrustful. In this Letter, we show that for bit commitment—one of the most basic primitives within the model—the answer is positive. We present a device-independent (imperfect) bit-commitment protocol, where Alice’s and Bob’s cheating probabilities are ≃0.854 and (3)/(4), which we then use to construct a device-independent coin flipping protocol with bias ≲0.336.
Very low bit rate voice for packetized mobile applications
Knittle, C.D.; Malone, K.T. )
1991-01-01
This paper reports that transmitting digital voice via packetized mobile communications systems that employ relatively short packet lengths and narrow bandwidths often necessitates very low bit rate coding of the voice data. Sandia National Laboratories is currently developing an efficient voice coding system operating at 800 bits per second (bps). The coding scheme is a modified version of the 2400 bps NSA LPC-10e standard. The most significant modification to the LPC-10e scheme is the vector quantization of the line spectrum frequencies associated with the synthesis filters. An outline of a hardware implementation for the 800 bps coder is presented. The speech quality of the coder is generally good, although speaker recognition is not possible. Further research is being conducted to reduce the memory requirements and complexity of the vector quantizer, and to increase the quality of the reconstructed speech. This work may be of use dealing with nuclear materials.
Very low bit rate voice for packetized mobile applications
Knittle, C.D.; Malone, K.T.
1991-01-01
Transmitting digital voice via packetized mobile communications systems that employ relatively short packet lengths and narrow bandwidths often necessitates very low bit rate coding of the voice data. Sandia National Laboratories is currently developing an efficient voice coding system operating at 800 bits per second (bps). The coding scheme is a modified version of the 2400 bps NSA LPC-10e standard. The most significant modification to the LPC-10e scheme is the vector quantization of the line spectrum frequencies associated with the synthesis filters. An outline of a hardware implementation for the 800 bps coder is presented. The speech quality of the coder is generally good, although speaker recognition is not possible. Further research is being conducted to reduce the memory requirements and complexity of the vector quantizer, and to increase the quality of the reconstructed speech. 4 refs., 2 figs., 3 tabs.
Phasing piston error in segmented telescopes.
Jiang, Junlun; Zhao, Weirui
2016-08-22
To achieve a diffraction-limited imaging, the piston errors between the segments of the segmented primary mirror telescope should be reduced to λ/40 RMS. We propose a method to detect the piston error by analyzing the intensity distribution on the image plane according to the Fourier optics principle, which can capture segments with the piston errors as large as the coherence length of the input light and reduce these to 0.026λ RMS (λ = 633nm). This method is adaptable to any segmented and deployable primary mirror telescope. Experiments have been carried out to validate the feasibility of the method. PMID:27557192
Conditional Standard Errors of Measurement for Composite Scores Using IRT
ERIC Educational Resources Information Center
Kolen, Michael J.; Wang, Tianyou; Lee, Won-Chan
2012-01-01
Composite scores are often formed from test scores on educational achievement test batteries to provide a single index of achievement over two or more content areas or two or more item types on that test. Composite scores are subject to measurement error, and as with scores on individual tests, the amount of error variability typically depends on…
Error control techniques for satellite and space communications
NASA Technical Reports Server (NTRS)
Costello, Daniel J., Jr.
1994-01-01
The unequal error protection capabilities of convolutional and trellis codes are studied. In certain environments, a discrepancy in the amount of error protection placed on different information bits is desirable. Examples of environments which have data of varying importance are a number of speech coding algorithms, packet switched networks, multi-user systems, embedded coding systems, and high definition television. Encoders which provide more than one level of error protection to information bits are called unequal error protection (UEP) codes. In this work, the effective free distance vector, d, is defined as an alternative to the free distance as a primary performance parameter for UEP convolutional and trellis encoders. For a given (n, k), convolutional encoder, G, the effective free distance vector is defined as the k-dimensional vector d = (d(sub 0), d(sub 1), ..., d(sub k-1)), where d(sub j), the j(exp th) effective free distance, is the lowest Hamming weight among all code sequences that are generated by input sequences with at least one '1' in the j(exp th) position. It is shown that, although the free distance for a code is unique to the code and independent of the encoder realization, the effective distance vector is dependent on the encoder realization.
Efficient delivery techniques for variable-bit-rate multimedia
NASA Astrophysics Data System (ADS)
Zhao, Yanping; Eager, Derek L.; Vernon, Mary K.
2001-12-01
Two key technologies enabling scalable on-demand delivery of stored multimedia content are work-ahead smoothing and multicast delivery. Work-ahead smoothing reduces the burstiness of variable bit rate streams, simplifying server and network resource allocation. Recent multicast delivery techniques such as patching or bandwidth skimming serve clients that request the same content close together in time with (partially) shared multicasts, greatly reducing required server bandwidth. Although previous studies of work-ahead smoothing have generally assumed very limited client buffer space, in a number of contexts of current interest (such as systems that have significant settop storage), it becomes feasible to fully smooth variable bit rate content. We quantify the start-up delay and settop storage requirements of full smoothing for a number of sample variable bit rate objects. We then evaluate a fundamental conflict between aggressive smoothing and the new multicast delivery techniques. Work-ahead smoothing requires sending data for high rate portions of an object earlier than it is needed for playback, while multicast techniques yield their greatest benefit when data is delivered within each stream as late as possible so that more clients can share reception of that data. A new multicast delivery technique is proposed that can accommodate aggressive smoothing with increased efficiency in comparison to previous techniques, particularly for high request rates.
Naidoo, Kovin S; Jaggernath, Jyoti
2012-01-01
Global estimates indicate that more than 2.3 billion people in the world suffer from poor vision due to refractive error; of which 670 million people are considered visually impaired because they do not have access to corrective treatment. Refractive errors, if uncorrected, results in an impaired quality of life for millions of people worldwide, irrespective of their age, sex and ethnicity. Over the past decade, a series of studies using a survey methodology, referred to as Refractive Error Study in Children (RESC), were performed in populations with different ethnic origins and cultural settings. These studies confirmed that the prevalence of uncorrected refractive errors is considerably high for children in low-and-middle-income countries. Furthermore, uncorrected refractive error has been noted to have extensive social and economic impacts, such as limiting educational and employment opportunities of economically active persons, healthy individuals and communities. The key public health challenges presented by uncorrected refractive errors, the leading cause of vision impairment across the world, require urgent attention. To address these issues, it is critical to focus on the development of human resources and sustainable methods of service delivery. This paper discusses three core pillars to addressing the challenges posed by uncorrected refractive errors: Human Resource (HR) Development, Service Development and Social Entrepreneurship. PMID:22944755
Uncorrected refractive errors.
Naidoo, Kovin S; Jaggernath, Jyoti
2012-01-01
Global estimates indicate that more than 2.3 billion people in the world suffer from poor vision due to refractive error; of which 670 million people are considered visually impaired because they do not have access to corrective treatment. Refractive errors, if uncorrected, results in an impaired quality of life for millions of people worldwide, irrespective of their age, sex and ethnicity. Over the past decade, a series of studies using a survey methodology, referred to as Refractive Error Study in Children (RESC), were performed in populations with different ethnic origins and cultural settings. These studies confirmed that the prevalence of uncorrected refractive errors is considerably high for children in low-and-middle-income countries. Furthermore, uncorrected refractive error has been noted to have extensive social and economic impacts, such as limiting educational and employment opportunities of economically active persons, healthy individuals and communities. The key public health challenges presented by uncorrected refractive errors, the leading cause of vision impairment across the world, require urgent attention. To address these issues, it is critical to focus on the development of human resources and sustainable methods of service delivery. This paper discusses three core pillars to addressing the challenges posed by uncorrected refractive errors: Human Resource (HR) Development, Service Development and Social Entrepreneurship. PMID:22944755
A 15-bit incremental sigma-delta ADC for CMOS image sensor
NASA Astrophysics Data System (ADS)
Chen, Nan; Li, Zhengfen; Zhong, Shengyou; Zou, Mei; Yao, Libin
2015-04-01
An incremental sigma-delta ADC is designed for column-parallel ADC array in CMOS image sensor. Sigma-delta modulator with single-loop single-bit structure is chosen for power consumption and performance reasons. Second-order modulator is used to reduce conversion time, without stability problem and large area accompanied by higher order sigma-delta modulator. The asymmetric current mirror amplifier used in integrator reduces more than 30% power dissipation. The digital filter and decimator are implemented by counters and adders with significantly reduced chip area and power consumption. A Clock generator is shared by 8 ADCs for trade-off among power, area and clock loading. The ADC array is implemented in a 0.18-μm CMOS technology and clocked at 10 MHz, and the simulated resolution achieves 15-bit with 255 clock cycles. The average power consumption per ADC is 118 μW including clock generator, and the area is only 0.0053 μm2.
PEALL4: a 4-channel, 12-bit, 40-MSPS, Power Efficient and Low Latency SAR ADC
NASA Astrophysics Data System (ADS)
Rarbi, F.; Dzahini, D.; Gallin-Martel, L.; Bouvier, J.; Zeloufi, M.; Trocme, B.; Gabaldon Ruiz, C.
2015-01-01
The PEALL4 chip is a Power Efficient And Low Latency 4-channels, 12-bit and 40-MSPS successive approximation register (SAR) ADC. It was designed featuring a very short latency time in the context of ATLAS Liquid Argon Calorimeter phase I upgrade. Moreover this design could be a good option for ATLAS phase II and other High Energy Physics (HEP) projects. The full functionality of the converter is achieved by an embedded high-speed clock frequency conversion generated by the ADC itself. The design and testing results of the PEALL4 chip implemented in a commercial 130nm CMOS process are presented. The size of this 4-channel ADC with embedded voltage references and sLVS output serializer is 2.8x3.4 mm2. The chip presents a short latency time less than 25 ns defined from the very beginning of the sampling to the last conversion bit made available. A total power consumption below 27mW per channel is measured including the reference buffer and the sLVS serializer.
A 4 GHz 32 bit direct digital frequency synthesizer based on a novel architecture
NASA Astrophysics Data System (ADS)
Jin, Wu; Jianwu, Chen; Danyu, Wu; Lei, Zhou; Fan, Jiang; Zhi, Jin; Xinyu, Liu
2013-11-01
This paper presents a novel direct digital frequency synthesizer (DDFS) architecture based on nonlinear DAC coarse quantization and the ROM-based piecewise approximation method, which has the advantages of high speed, low power and low hardware resources. By subdividing the sinusoid into a collection of phase segments, the same initial value of each segment is realized by a nonlinear DAC. The ROM is decomposed with a coarse ROM and fine ROM using the piecewise approximation method. Then, the coarse ROM stores the offsets between the initial value of the common segment and the initial value of each line in the same segment. Meanwhile, the fine ROM stores the differences between the line values and the initial value of each line. A ROM compression ratio of 32 can be achieved in the case of 11 bit phase and 9 bit amplitude. Based on the above method, a prototype chip was fabricated using 1.4 μm GaAs HBT technology. The measurement shows an average spurious-free dynamic range (SFDR) of 45 dBc, with the worst SFDR only 40.07 dBc at a 4.0 GHz clock. The chip area is 4.6 × 3.7 mm2 and it consumes 7 W from a -4.9 V power supply.
Insulin use: preventable errors.
2014-01-01
Insulin is vital for patients with type 1 diabetes and useful for certain patients with type 2 diabetes. The serious consequences of insulin-related medication errors are overdose, resulting in severe hypoglycaemia, causing seizures, coma and even death; or underdose, resulting in hyperglycaemia and sometimes ketoacidosis. Errors associated with the preparation and administration of insulin are often reported, both outside and inside the hospital setting. These errors are preventable. By analysing reports from organisations devoted to medication error prevention and from poison control centres, as well as a few studies and detailed case reports of medication errors, various types of error associated with insulin use have been identified, especially in the hospital setting. Generally, patients know more about the practicalities of their insulin treatment than healthcare professionals with intermittent involvement. Medication errors involving insulin can occur at each step of the medication-use process: prescribing, data entry, preparation, dispensing and administration. When prescribing insulin, wrong-dose errors have been caused by the use of abbreviations, especially "U" instead of the word "units" (often resulting in a 10-fold overdose because the "U" is read as a zero), or by failing to write the drug's name correctly or in full. In electronic prescribing, the sheer number of insulin products is a source of confusion and, ultimately, wrong-dose errors, and often overdose. Prescribing, dispensing or administration software is rarely compatible with insulin prescriptions in which the dose is adjusted on the basis of the patient's subsequent capillary blood glucose readings, and can therefore generate errors. When preparing and dispensing insulin, a tuberculin syringe is sometimes used instead of an insulin syringe, leading to overdose. Other errors arise from confusion created by similar packaging, between different insulin products or between insulin and other
NASA Technical Reports Server (NTRS)
1987-01-01
In a complex computer environment there is ample opportunity for error, a mistake by a programmer, or a software-induced undesirable side effect. In insurance, errors can cost a company heavily, so protection against inadvertent change is a must for the efficient firm. The data processing center at Transport Life Insurance Company has taken a step to guard against accidental changes by adopting a software package called EQNINT (Equations Interpreter Program). EQNINT cross checks the basic formulas in a program against the formulas that make up the major production system. EQNINT assures that formulas are coded correctly and helps catch errors before they affect the customer service or its profitability.
NASA Astrophysics Data System (ADS)
Kumar, Santosh; Bisht, Ashish; Singh, Gurdeep; Choudhary, Kuldeep; Raina, K. K.; Amphawan, Angela
2015-12-01
The Mach-Zehnder interferometer (MZI) structures collectively show powerful capability in switching an input optical signal to a desired output port from a collection of output ports. Hence, it is possible to construct complex optical combinational digital circuits using the electro-optic effect constituting MZI structure as a basic building block. Optical switches have been designed for 1-bit and 2-bit magnitude comparators based on electro-optic effect using Mach-Zehnder interferometers. The paper constitutes a mathematical description of the proposed device and thereafter simulation using MATLAB. Analysis of some factors influencing the performances of proposed device has been discussed properly. The study is verified using beam propagation method.
NASA Astrophysics Data System (ADS)
Youssefi, Bahar; Moravvej-Farshi, Mohammad Kazem; Granpayeh, Nosrat
2012-06-01
We have demonstrated the performance of a novel design for a single wavelength 2-bit all-optical analog-to-digital converter (ADC). This converter consists of two high efficient channel drop filters with a coupled cavity-based wavelength selective reflector in a 2D photonic crystal with total length of 15.87 μm. The A/D conversion is achieved by using nonlinear Kerr effect in the cavities. The output ports switch to state '1' at different input power levels to generate unique states preferred for an ADC. This conversion is simulated by the finite difference time domain (FDTD) method for 5 different power levels. The proposed structure can function as a two-bit ADC with a 60 mW/μm input pulse and its maximum sampling rate is found to be ~ 45 GS/s.
Core drill's bit is replaceable without withdrawal of drill stem - A concept
NASA Technical Reports Server (NTRS)
Rushing, F. C.; Simon, A. B.
1970-01-01
Drill bit is divided into several sectors. When collapsed, the outside diameter is forced down the drill stem, when it reaches bottom the sectors are forced outward and form a cutting bit. A dulled bit is retracted by reversal of this procedure.
... the lens can cause refractive errors. What is refraction? Refraction is the bending of light as it passes ... rays entering the eye, causing a more precise refraction or focus. In many cases, contact lenses provide ...
Anumba, Dilly O C
2013-08-01
Prenatal screening and diagnosis are integral to antenatal care worldwide. Prospective parents are offered screening for common fetal chromosomal and structural congenital malformations. In most developed countries, prenatal screening is routinely offered in a package that includes ultrasound scan of the fetus and the assay in maternal blood of biochemical markers of aneuploidy. Mistakes can arise at any point of the care pathway for fetal screening and diagnosis, and may involve individual or corporate systemic or latent errors. Special clinical circumstances, such as maternal size, fetal position, and multiple pregnancy, contribute to the complexities of prenatal diagnosis and to the chance of error. Clinical interventions may lead to adverse outcomes not caused by operator error. In this review I discuss the scope of the errors in prenatal diagnosis, and highlight strategies for their prevention and diagnosis, as well as identify areas for further research and study to enhance patient safety. PMID:23725900