Science.gov

Sample records for optimization-based bit allocation

  1. 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.

  2. 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.

  3. Bit-rate allocation for multiple video streams using a pricing-based mechanism.

    PubMed

    Tiwari, Mayank; Groves, Theodore; Cosman, Pamela

    2011-11-01

    We consider the problem of bit-rate allocation for multiple video users sharing a common transmission channel. Previously, overall quality of multiple users was improved by exploiting relative video complexity. Users with high-complexity video benefit at the expense of video quality reduction for other users with simpler videos. The quality of all users can be improved by collectively allocating the bit rate in a centralized fashion which requires sharing video information with a central controller. In this paper, we present an informationally decentralized bit-rate allocation for multiple users where a user only needs to inform his demand to an allocator. Each user separately calculates his bit-rate demand based on his video complexity and bit-rate price, where the bit-rate price is announced by the allocator. The allocator adjusts the bit-rate price for the next period based on the bit rate demanded by the users and the total available bit-rate supply. Simulation results show that all users improve their quality by the pricing-based decentralized bit-rate allocation method compared with their allocation when acting individually. The results of our proposed method are comparable to the centralized bit-rate allocation. PMID:21518661

  4. Adaptive differential pulse-code modulation with adaptive bit allocation

    NASA Astrophysics Data System (ADS)

    Frangoulis, E. D.; Yoshida, K.; Turner, L. F.

    1984-08-01

    Studies have been conducted regarding the possibility to obtain good quality speech at data rates in the range from 16 kbit/s to 32 kbit/s. The techniques considered are related to adaptive predictive coding (APC) and adaptive differential pulse-code modulation (ADPCM). At 16 kbit/s adaptive transform coding (ATC) has also been used. The present investigation is concerned with a new method of speech coding. The described method employs adaptive bit allocation, similar to that used in adaptive transform coding, together with adaptive differential pulse-code modulation, employing first-order prediction. The new method has the objective to improve the quality of the speech over that which can be obtained with conventional ADPCM employing a fourth-order predictor. Attention is given to the ADPCM-AB system, the design of a subjective test, and the application of switched preemphasis to ADPCM.

  5. Proposed first-generation WSQ bit allocation procedure

    SciTech Connect

    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.

  6. 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.

  7. A unified framework of unsupervised subjective optimized bit allocation for multiple video object coding

    NASA Astrophysics Data System (ADS)

    Chen, Zhenzhong; Han, Junwei; Ngan, King Ngi

    2005-10-01

    MPEG-4 treats a scene as a composition of several objects or so-called video object planes (VOPs) that are separately encoded and decoded. Such a flexible video coding framework makes it possible to code different video object with different distortion scale. It is necessary to analyze the priority of the video objects according to its semantic importance, intrinsic properties and psycho-visual characteristics such that the bit budget can be distributed properly to video objects to improve the perceptual quality of the compressed video. This paper aims to provide an automatic video object priority definition method based on object-level visual attention model and further propose an optimization framework for video object bit allocation. One significant contribution of this work is that the human visual system characteristics are incorporated into the video coding optimization process. Another advantage is that the priority of the video object can be obtained automatically instead of fixing weighting factors before encoding or relying on the user interactivity. To evaluate the performance of the proposed approach, we compare it with traditional verification model bit allocation and the optimal multiple video object bit allocation algorithms. Comparing with traditional bit allocation algorithms, the objective quality of the object with higher priority is significantly improved under this framework. These results demonstrate the usefulness of this unsupervised subjective quality lifting framework.

  8. 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.

  9. MSE optimal bit-rate allocation in JPEG2000 Part 2 compression applied to a 3D data set

    NASA Astrophysics Data System (ADS)

    Kosheleva, Olga M.; Cabrera, Sergio D.; Usevitch, Bryan E.; Aguirre, Alberto; Vidal, Edward, Jr.

    2004-10-01

    A bit rate allocation (BRA) strategy is needed to optimally compress three-dimensional (3-D) data on a per-slice basis, treating it as a collection of two-dimensional (2-D) slices/components. This approach is compatible with the framework of JPEG2000 Part 2 which includes the option of pre-processing the slices with a decorrelation transform in the cross-component direction so that slices of transform coefficients are compressed. In this paper, we illustrate the impact of a recently developed inter-slice rate-distortion optimal bit-rate allocation approach that is applicable to this compression system. The approach exploits the MSE optimality of all JPEG2000 bit streams for all slices when each is produced in the quality progressive mode. Each bit stream can be used to produce a rate-distortion curve (RDC) for each slice that is MSE optimal at each bit rate of interest. The inter-slice allocation approach uses all RDCs for all slices to optimally select an overall optimal set of bit rates for all the slices using a constrained optimization procedure. The optimization is conceptually similar to Post-Compression Rate-Distortion optimization that is used within JPEG2000 to optimize bit rates allocated to codeblocks. Results are presented for two types of data sets: a 3-D computed tomography (CT) medical image, and a 3-D metereological data set derived from a particular modeling program. For comparison purposes, compression results are also illustrated for the traditional log-variance approach and for a uniform allocation strategy. The approach is illustrated using two decorrelation tranforms (the Karhunen Loeve transform, and the discrete wavelet transform) for which the inter-slice allocation scheme has the most impact.

  10. Bit and Power Allocation in Constrained Multicarrier Systems: The Single-User Case

    NASA Astrophysics Data System (ADS)

    Papandreou, Nikolaos; Antonakopoulos, Theodore

    2007-12-01

    Multicarrier modulation is a powerful transmission technique that provides improved performance in various communication fields. A fundamental topic of multicarrier communication systems is the bit and power loading, which is addressed in this article as a constrained multivariable nonlinear optimization problem. In particular, we present the main classes of loading problems, namely, rate maximization and margin maximization, and we discuss their optimal solutions for the single-user case. Initially, the classical water-filling solution subject to a total power constraint is presented using the Lagrange multipliers optimization approach. Next, the peak-power constraint is included and the concept of cup-limited waterfilling is introduced. The loading problem is also addressed subject to the integer-bit restriction and the optimal discrete solution is examined using combinatorial optimization methods. Furthermore, we investigate the duality conditions of the rate maximization and margin maximization problems and we highlight various ideas for low-complexity loading algorithms. This article surveys and reviews existing results on resource allocation in constrained multicarrier systems and presents new trends in this area.

  11. JAVA implemented MSE optimal bit-rate allocation applied to 3-D hyperspectral imagery using JPEG2000 compression

    NASA Astrophysics Data System (ADS)

    Melchor, J. L., Jr.; Cabrera, S. D.; Aguirre, A.; Kosheleva, O. M.; Vidal, E., Jr.

    2005-08-01

    This paper describes an efficient algorithm and its Java implementation for a recently developed mean-squared error (MSE) rate-distortion optimal (RDO) inter-slice bit-rate allocation (BRA) scheme applicable to the JPEG2000 Part 2 (J2KP2) framework. Its performance is illustrated on hyperspectral imagery data using the J2KP2 with the Karhunen- Loeve transform (KLT) for decorrelation. The results are contrasted with those obtained using the traditional logvariance based BRA method and with the original RDO algorithm. The implementation has been developed as a Java plug-in to be incorporated into our evolving multi-dimensional data compression software tool denoted CompressMD. The RDO approach to BRA uses discrete rate distortion curves (RDCs) for each slice of transform coefficients. The generation of each point on a RDC requires a full decompression of that slice, therefore, the efficient version minimizes the number of RDC points needed from each slice by using a localized coarse-to-fine approach denoted RDOEfficient. The scheme is illustrated in detail using a subset of 10 bands of hyperspectral imagery data and is contrasted to the original RDO implementation and the traditional (log-variance) method of BRA showing that better results are obtained with the RDO methods. The three schemes are also tested on two hyperspectral imagery data sets with all bands present: the Cuprite radiance data from AVIRIS and a set derived from the Hyperion satellite. The results from the RDO and RDOEfficient are very close to each other in the MSE sense indicating that the adaptive approach can find almost the same BRA solution. Surprisingly, the traditional method also performs very close to the RDO methods, indicating that it is very close to being optimal for these types of data sets.

  12. Drag bit construction

    DOEpatents

    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.

  13. Drag bit construction

    DOEpatents

    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.

  14. Remote drill bit loader

    SciTech Connect

    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.

  15. Remote drill bit loader

    DOEpatents

    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.

  16. Drag bit and cutters

    SciTech Connect

    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.

  17. Double acting bit holder

    DOEpatents

    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.

  18. Hey! A Louse Bit Me!

    MedlinePlus

    ... Sledding, Skiing, Snowboarding, Skating Crushes What's a Booger? Hey! A Louse Bit Me! KidsHealth > For Kids > Hey! A Louse Bit Me! Print A A A ... For Kids For Parents MORE ON THIS TOPIC Hey! A Gnat Bit Me! Hey! A Flea Bit ...

  19. Lubrication of rotary rock bits

    SciTech Connect

    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.

  20. Continuous coring drill bit

    SciTech Connect

    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.

  1. Positional information, in bits

    PubMed Central

    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

  2. 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.

  3. Drilling bits optimized for the Paris basin

    SciTech Connect

    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.

  4. 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.

  5. Drag-type drill bit

    SciTech Connect

    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.

  6. Drill bit assembly for releasably retaining a drill bit cutter

    SciTech Connect

    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.

  7. Hey! A Chigger Bit Me!

    MedlinePlus

    ... Sledding, Skiing, Snowboarding, Skating Crushes What's a Booger? Hey! A Chigger Bit Me! KidsHealth > For Kids > Hey! A Chigger Bit Me! Print A A A ... For Kids For Parents MORE ON THIS TOPIC Hey! A Fire Ant Stung Me! Hey! A Gnat ...

  8. 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.

  9. Research on optimization-based design

    NASA Technical Reports Server (NTRS)

    Balling, R. J.; Parkinson, A. R.; Free, J. C.

    1989-01-01

    Research on optimization-based design is discussed. Illustrative examples are given for cases involving continuous optimization with discrete variables and optimization with tolerances. Approximation of computationally expensive and noisy functions, electromechanical actuator/control system design using decomposition and application of knowledge-based systems and optimization for the design of a valve anti-cavitation device are among the topics covered.

  10. Optimization-Based Models of Muscle Coordination

    PubMed Central

    Prilutsky, Boris I.; Zatsiorsky, Vladimir M.

    2010-01-01

    Optimization-based models may provide reasonably accurate estimates of activation and force patterns of individual muscles in selected well-learned tasks with submaximal efforts. Such optimization criteria as minimum energy expenditure, minimum muscle fatigue, and minimum sense of effort seem most promising. PMID:11800497

  11. Optimization-based models of muscle coordination.

    PubMed

    Prilutsky, Boris I; Zatsiorsky, Vladimir M

    2002-01-01

    Optimization-based models may provide reasonably accurate estimates of activation and force patterns of individual muscles in selected well-learned tasks with submaximal efforts. Such optimization criteria as minimum energy expenditure, minimum muscle fatigue, and minimum sense of effort seem most promising. PMID:11800497

  12. 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.

  13. 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.

  14. Experimental unconditionally secure bit commitment.

    PubMed

    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

  15. 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.

  16. Optimal encryption of quantum bits

    SciTech Connect

    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.

  17. String bit models for superstring

    SciTech Connect

    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.

  18. String bit models for superstring

    SciTech Connect

    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.

  19. Bit-level systolic arrays

    SciTech Connect

    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.

  20. Drill bit method and apparatus

    SciTech Connect

    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.

  1. Drill bit and method of renewing drill bit cutting face

    SciTech Connect

    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.

  2. Bit by bit: the Darwinian basis of life.

    PubMed

    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

  3. 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.

  4. Introduction to the Mu-bit

    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).

  5. Local, Optimization-based Simplicial Mesh Smoothing

    Energy Science and Technology Software Center (ESTSC)

    1999-12-09

    OPT-MS is a C software package for the improvement and untangling of simplicial meshes (triangles in 2D, tetrahedra in 3D). Overall mesh quality is improved by iterating over the mesh vertices and adjusting their position to optimize some measure of mesh quality, such as element angle or aspect ratio. Several solution techniques (including Laplacian smoothing, "Smart" Laplacian smoothing, optimization-based smoothing and several combinations thereof) and objective functions (for example, element angle, sin (angle), and aspectmore » ratio) are available to the user for both two and three-dimensional meshes. If the mesh contains invalid elements (those with negative area) a different optimization algorithm for mesh untangling is provided.« less

  6. Hey! A Bedbug Bit Me!

    MedlinePlus

    ... 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 ...

  7. Hey! A Mosquito Bit Me!

    MedlinePlus

    ... 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 ...

  8. Hey! A Tarantula Bit Me!

    MedlinePlus

    ... 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 ...

  9. Stability of single skyrmionic bits

    PubMed Central

    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

  10. 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.

  11. Development of PDC Bits for Downhole Motors

    SciTech Connect

    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.

  12. Panel focuses on diamond shear bit care

    SciTech Connect

    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.

  13. Bit by Bit: The Darwinian Basis of Life

    PubMed Central

    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

  14. 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…

  15. Proper nozzle location, bit profile, and cutter arrangement affect PDC-bit performance significantly

    SciTech Connect

    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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Computer Processor Allocator

    Energy Science and Technology Software Center (ESTSC)

    2004-03-01

    The Compute Processor Allocator (CPA) provides an efficient and reliable mechanism for managing and allotting processors in a massively parallel (MP) computer. It maintains information in a database on the health. configuration and allocation of each processor. This persistent information is factored in to each allocation decision. The CPA runs in a distributed fashion to avoid a single point of failure.

  1. Josephson 32-bit shift register

    SciTech Connect

    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.

  2. FastBit Reference Manual

    SciTech Connect

    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.

  3. Improvement of PDC bit`s performance at high rotary speed

    SciTech Connect

    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.

  4. REVERSIBLE N-BIT TO N-BIT INTEGER HAAR-LIKE TRANSFORMS

    SciTech Connect

    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.

  5. Hey! A Brown Recluse Spider Bit Me!

    MedlinePlus

    ... 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 ...

  6. 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.

  7. 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.

  8. An Improved N-Bit to N-Bit Reversible Haar-Like Transform

    SciTech Connect

    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.

  9. Bit-string scattering theory

    SciTech Connect

    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.

  10. Smoothing variable-bit-rate video in an internetwork

    NASA Astrophysics Data System (ADS)

    Rexford, Jennifer; Towsley, Don

    1997-10-01

    The burstiness of compressed video complicates the provisioning of network resources for emerging multimedia services. For stored video applications, the server can smooth the variable-bit-rate stream by prefetching frames into the client playback buffer in advanced of each burst. Drawing on a priori knowledge of the frame lengths and client buffer size, such bandwidth smoothing techniques can minimize the peak and variability of the rate requirements while avoiding underflow and overflow of the playback buffer. However, in an internetworking environment, a single service provider typically does not control the entire path from the stored-video server to the client buffer. To develop efficient techniques for transmitting variable-bit- rate video across a portion of the route, we investigate bandwidth smoothing across a tandem of nodes, which may or may not include the server and client sites. We show that it is possible to compute an optimal transmission schedule for the tandem system by solving a collection of independent single-link problems. To develop efficient techniques for minimizing the network bandwidth requirements, we characterize how the peak rate varies as a function of the buffer allocation and the playback delay. Simulation experiments illustrate the subtle interplay between buffer space, playback delay, and bandwidth requirements for a collection of full-length video traces. These analytic and empirical results suggest effective guidelines for provisioning network services for the transmission of compressed video.

  11. Allocation without locking

    SciTech Connect

    Appel, A.W.

    1988-01-01

    In a programming environment with both concurrency and automatic garbage collection, the allocation and initialization of a new record is a sensitive matter: if it is interrupted halfway through, the allocating process may be in a state that the garbage collector can't understand. In particular, the collector won't know which words of the new record have been initialized and which are meaningless (and unsafe to transverse). For this reason, parallel implementations usually use a locking or semaphore mechanism to ensure that allocation is an atomic operation. The locking significantly adds to the cost of allocation. This paper shows that allocation can run extremely quickly even in a multi-thread environment: open-coded, without locking.

  12. 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.

  13. 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.

  14. PDC bits find applications in Oklahoma drilling

    SciTech Connect

    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.

  15. 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.

  16. FastBit: Interactively Searching Massive Data

    SciTech Connect

    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.

  17. 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.

  18. Diffusion bonding of Stratapax for drill bits

    SciTech Connect

    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.

  19. 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.

  20. The Unobtrusive Memory Allocator

    Energy Science and Technology Software Center (ESTSC)

    2003-03-31

    This library implements a memory allocator/manager which ask its host program or library for memory refions to manage rather than requesting them from the operating system. This allocator supports multiple distinct heaps within a single executable, each of which may grow either upward or downward in memory. The GNU mmalloc library has been modified in such a way that its allocation algorithms have been preserved, but the manner in which it obtains regions to managemore » has been changed to request memory from the host program or library. Additional modifications allow the allocator to manage each heap as either upward or downward-growing. By allowing the hosting program or library to determine what memory is managed, this package allows a greater degree of control than other memory allocation/management libraries. Additional distinguishing features include the ability to manage multiple distinct heaps with in a single executable, each of which may grow either upward or downward in memory. The most common use of this library is in conjunction with the Berkeley Unified Parallel C (UPC) Runtime Library. This package is a modified version of the LGPL-licensed "mmalloc" allocator from release 5.2 of the "gdb" debugger's source code.« less

  1. Antenna Allocation in MIMO Radar with Widely Separated Antennas for Multi-Target Detection

    PubMed Central

    Gao, Hao; Wang, Jian; Jiang, Chunxiao; Zhang, Xudong

    2014-01-01

    In this paper, we explore a new resource called multi-target diversity to optimize the performance of multiple input multiple output (MIMO) radar with widely separated antennas for detecting multiple targets. In particular, we allocate antennas of the MIMO radar to probe different targets simultaneously in a flexible manner based on the performance metric of relative entropy. Two antenna allocation schemes are proposed. In the first scheme, each antenna is allocated to illuminate a proper target over the entire illumination time, so that the detection performance of each target is guaranteed. The problem is formulated as a minimum makespan scheduling problem in the combinatorial optimization framework. Antenna allocation is implemented through a branch-and-bound algorithm and an enhanced factor 2 algorithm. In the second scheme, called antenna-time allocation, each antenna is allocated to illuminate different targets with different illumination time. Both antenna allocation and time allocation are optimized based on illumination probabilities. Over a large range of transmitted power, target fluctuations and target numbers, both of the proposed antenna allocation schemes outperform the scheme without antenna allocation. Moreover, the antenna-time allocation scheme achieves a more robust detection performance than branch-and-bound algorithm and the enhanced factor 2 algorithm when the target number changes. PMID:25350505

  2. Nugget hardfacing toughens roller cone bits

    SciTech Connect

    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.

  3. Rig site computer optimizes bit weight

    SciTech Connect

    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.

  4. 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.

  5. Managing the number of tag bits transmitted in a bit-tracking RFID collision resolution protocol.

    PubMed

    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

  6. Managing the Number of Tag Bits Transmitted in a Bit-Tracking RFID Collision Resolution Protocol

    PubMed Central

    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

  7. Evaluations of bit sleeve and twisted-body bit designs for controlling roof bolter dust

    PubMed Central

    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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. On combining Laplacian and optimization-based mesh smoothing techniques

    SciTech Connect

    Freitag, L.A.

    1997-07-01

    Local mesh smoothing algorithms have been shown to be effective in repairing distorted elements in automatically generated meshes. The simplest such algorithm is Laplacian smoothing, which moves grid points to the geometric center of incident vertices. Unfortunately, this method operates heuristically and can create invalid meshes or elements of worse quality than those contained in the original mesh. In contrast, optimization-based methods are designed to maximize some measure of mesh quality and are very effective at eliminating extremal angles in the mesh. These improvements come at a higher computational cost, however. In this article the author proposes three smoothing techniques that combine a smart variant of Laplacian smoothing with an optimization-based approach. Several numerical experiments are performed that compare the mesh quality and computational cost for each of the methods in two and three dimensions. The author finds that the combined approaches are very cost effective and yield high-quality meshes.

  13. Anti-incendive coal cutter bits

    SciTech Connect

    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.

  14. Shaft drill bit with overlapping cutter arrangement

    SciTech Connect

    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.

  15. 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.

  16. Protected Polycrystalline Diamond Compact Bits For Hard Rock Drilling

    SciTech Connect

    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.

  17. Bit-rate prediction for look-ahead coding with AVC

    NASA Astrophysics Data System (ADS)

    Beermann, Markus

    2004-01-01

    Compression of digitized video highly depends on, and varies with, the signal to be compressed. The relation of quantizer, distortion and rate needs to be modeled when control in a system involving video compression is asked for. An experimental analysis of the optimized video codec AVC of ITU-T and MPEG shows that its rate behavior can be modeled accurately enough to predict bit-rate on macroblock-level. Given information of allocated rates from a pre-encoding analysis step, the bit-rate profile at any different quantizer setting for the video can be predicted. Experiments, comparing predicted rate against actual encoding rate show good performance of the model.These reflect the performance of the model in rate-control schemes. A simple example pre-analysis rate-control based on the model will determine beforehand a possible rate-profile that the actual encoding should be able to follow with small quality variations. For a signal of varying complexity, a varying number of bits will be used to obtain constant quality. Such variations are limited by peak bit-rates and buffer-sizes that are defined by hypothetical reference decoders in AVC.

  18. 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.

  19. Jet bit with onboard deviation means

    SciTech Connect

    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.

  20. Security of quantum bit-string generation

    SciTech Connect

    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.

  1. REVERSIBLE N-BIT TO N-BIT INTEGER HAAR-LIKE TRANSFORMS

    SciTech Connect

    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.

  2. 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.

  3. Spectrum allocations above 40 GHz

    NASA Technical Reports Server (NTRS)

    Katzenstein, W. E.; Moore, R. P.; Kimball, H. G.

    1981-01-01

    The 1979 World Administrative Radio Conference (WARC-79) revised the International Table of Frequency Allocations to reflect increased interest and activity in the region of the EM spectrum above 40 GHz. The total width of the spectrum allocated (235 GHz) in the region above 40 GHz indicates the extent of this new spectrum resource, made accessible by advances in the state-of-the-art of telecommunications equipment. There are some striking differences between the approach to allocation above and below 40 GHz. For example, there are not bands allocated exclusively. This reflects the characteristics of propagation and the small antenna beamwidths achievable at these frequencies. Attention is given to atmospheric window and absorption band limits, allocations to satellite services, allocations to scientific services, allocations to terrestrial services, the future refinement of the radio regulations above 40 GHz, and allocations of WARC-79 and frequency management.

  4. Economics of spectrum allocation

    NASA Astrophysics Data System (ADS)

    Melody, W. H.

    The effective and efficient allocation and use of the spectrum can be ensured only by a set of sharing rules that will reflect the interests, values, and power of all affected parties. What is now happening is that the new interests and different values of the developing countries are pressing to change the international sharing rules established by a small group of high-technology nations. It is noted that the latter have established a massive telecommunications infrastructure on the basis of inherited sharing rules that reflect only their interests and a much simplified scarcity problem. Once long-term goals and underlying principles of allocation are established, communication technologies and markets can be directed, through a series of adjustment policies, to achieve them. A crucial first step in the creation of an international information environment in which 'free' flows will be balanced flows is the establishment of a balanced and equitable set of sharing rules for the radio spectrum.

  5. Myrmics Memory Allocator

    Energy Science and Technology Software Center (ESTSC)

    2011-09-23

    MMA is a stand-alone memory management system for MPI clusters. It implements a shared Partitioned Global Address Space, where multiple MPI processes request objects from the allocator and the latter provides them with system-wide unique memory addresses for each object. It provides applications with an intuitive way of managing the memory system in a unified way, thus enabling easier writing of irregular application code.

  6. Earth boring bit with eccentric seal boss

    SciTech Connect

    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.

  7. 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.

  8. Attention allocation before antisaccades.

    PubMed

    Klapetek, Anna; Jonikaitis, Donatas; Deubel, Heiner

    2016-01-01

    In the present study, we investigated the distribution of attention before antisaccades. We used a dual task paradigm, in which participants made prosaccades or antisaccades and discriminated the orientation of a visual probe shown at the saccade goal, the visual cue location (antisaccade condition), or a neutral location. Moreover, participants indicated whether they had made a correct antisaccade or an erroneous prosaccade. We observed that, while spatial attention in the prosaccade task was allocated only to the saccade goal, attention in the antisaccade task was allocated both to the cued location and to the antisaccade goal. This suggests parallel attentional selection of the cued and antisaccade locations. We further observed that in error trials--in which participants made an incorrect prosaccade instead of an antisaccade--spatial attention was biased towards the prosaccade goal. These erroneous prosaccades were mostly unnoticed and were often followed by corrective antisaccades with very short latencies (<100 ms). Data from error trials therefore provide further evidence for the parallel programming of the reflexive prosaccade to the cue and the antisaccade to the intended location. Taken together, our results suggest that attention allocation and saccade goal selection in the antisaccade task are mediated by a common competitive process. PMID:26790843

  9. 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.

  10. 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.

  11. Junk basket, bit and reamer stabilizer

    SciTech Connect

    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.

  12. 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.

  13. 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.

  14. 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

  15. Synaptic Tagging During Memory Allocation

    PubMed Central

    Rogerson, Thomas; Cai, Denise; Frank, Adam; Sano, Yoshitake; Shobe, Justin; Aranda, Manuel L.; Silva, Alcino J.

    2014-01-01

    There is now compelling evidence that the allocation of memory to specific neurons (neuronal allocation) and synapses (synaptic allocation) in a neurocircuit is not random and that instead specific mechanisms, such as increases in neuronal excitability and synaptic tagging and capture, determine the exact sites where memories are stored. We propose an integrated view of these processes, such that neuronal allocation, synaptic tagging and capture, spine clustering and metaplasticity reflect related aspects of memory allocation mechanisms. Importantly, the properties of these mechanisms suggest a set of rules that profoundly affect how memories are stored and recalled. PMID:24496410

  16. 50 CFR 660.323 - Pacific whiting allocations, allocation attainment, and inseason allocation reapportionment.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Pacific whiting allocations, allocation...) FISHERIES OFF WEST COAST STATES West Coast Groundfish Fisheries § 660.323 Pacific whiting allocations... amounts that will be harvested, or a combination of the two. Estimates of the amount of Pacific...

  17. 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.

  18. 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.

  19. Method to manufacture bit patterned magnetic recording media

    SciTech Connect

    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.

  20. Laboratory and field testing of improved geothermal rock bits

    SciTech Connect

    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.

  1. Reversible n-Bit to n-Bit Integer Haar-Like Transforms

    SciTech Connect

    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.

  2. An Optimization-based Atomistic-to-Continuum Coupling Method

    DOE PAGESBeta

    Olson, Derek; Bochev, Pavel B.; Luskin, Mitchell; Shapeev, Alexander V.

    2014-08-21

    In this paper, we present a new optimization-based method for atomistic-to-continuum (AtC) coupling. The main idea is to cast the latter as a constrained optimization problem with virtual Dirichlet controls on the interfaces between the atomistic and continuum subdomains. The optimization objective is to minimize the error between the atomistic and continuum solutions on the overlap between the two subdomains, while the atomistic and continuum force balance equations provide the constraints. Separation, rather then blending of the atomistic and continuum problems, and their subsequent use as constraints in the optimization problem distinguishes our approach from the existing AtC formulations. Finally,more » we present and analyze the method in the context of a one-dimensional chain of atoms modeled using a linearized two-body potential with next-nearest neighbor interactions.« less

  3. An Optimization-based Atomistic-to-Continuum Coupling Method

    SciTech Connect

    Olson, Derek; Bochev, Pavel B.; Luskin, Mitchell; Shapeev, Alexander V.

    2014-08-21

    In this paper, we present a new optimization-based method for atomistic-to-continuum (AtC) coupling. The main idea is to cast the latter as a constrained optimization problem with virtual Dirichlet controls on the interfaces between the atomistic and continuum subdomains. The optimization objective is to minimize the error between the atomistic and continuum solutions on the overlap between the two subdomains, while the atomistic and continuum force balance equations provide the constraints. Separation, rather then blending of the atomistic and continuum problems, and their subsequent use as constraints in the optimization problem distinguishes our approach from the existing AtC formulations. Finally, we present and analyze the method in the context of a one-dimensional chain of atoms modeled using a linearized two-body potential with next-nearest neighbor interactions.

  4. An Optimality-Based Fully-Distributed Watershed Ecohydrological Model

    NASA Astrophysics Data System (ADS)

    Chen, L., Jr.

    2015-12-01

    Watershed ecohydrological models are essential tools to assess the impact of climate change and human activities on hydrological and ecological processes for watershed management. Existing models can be classified as empirically based model, quasi-mechanistic and mechanistic models. The empirically based and quasi-mechanistic models usually adopt empirical or quasi-empirical equations, which may be incapable of capturing non-stationary dynamics of target processes. Mechanistic models that are designed to represent process feedbacks may capture vegetation dynamics, but often have more demanding spatial and temporal parameterization requirements to represent vegetation physiological variables. In recent years, optimality based ecohydrological models have been proposed which have the advantage of reducing the need for model calibration by assuming critical aspects of system behavior. However, this work to date has been limited to plot scale that only considers one-dimensional exchange of soil moisture, carbon and nutrients in vegetation parameterization without lateral hydrological transport. Conceptual isolation of individual ecosystem patches from upslope and downslope flow paths compromises the ability to represent and test the relationships between hydrology and vegetation in mountainous and hilly terrain. This work presents an optimality-based watershed ecohydrological model, which incorporates lateral hydrological process influence on hydrological flow-path patterns that emerge from the optimality assumption. The model has been tested in the Walnut Gulch watershed and shows good agreement with observed temporal and spatial patterns of evapotranspiration (ET) and gross primary productivity (GPP). Spatial variability of ET and GPP produced by the model match spatial distribution of TWI, SCA, and slope well over the area. Compared with the one dimensional vegetation optimality model (VOM), we find that the distributed VOM (DisVOM) produces more reasonable spatial

  5. Multi-Bit Nano-Electromechanical Nonvolatile Memory Cells (Zigzag T Cells) for the Suppression of Bit-to-Bit Interference.

    PubMed

    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

  6. Telescope Time Allocation Tool

    NASA Astrophysics Data System (ADS)

    Alves, J.

    2005-03-01

    TaToo is ESO's new Time Allocation Tool. This software scheduler is a combination of a user-friendly graphical user interface and an intelligent constraint-programming engine fine-tuned to ESO's scheduling problem. TaToo is able to produce a high quality and reliable schedule taking into consideration all constraints of the recommended programs for all telescopes in about 15 minutes. This performance allows schedulers at ESO-VISAS to simulate and evaluate different scenarios, optimize the scheduling of engineering activities at the observatories, and in the end construct the most science efficient schedule possible.

  7. [Organ allocation. Ethical issues].

    PubMed

    Cattorini, P

    2010-01-01

    The criteria for allocating organs are one of the most debated ethical issue in the transplantation programs. The article examines some rules and principles followed by "Nord Italia Transplant program", summarized in its Principles' Charter and explained in a recent interdisciplinary book. General theories of justice and their application to individual clinical cases are commented and evaluated, in order to foster a public, democratic, transparent debate among professionals and citizens, scientific associations and customers' organizations. Some specific moral dilemmas are focused regarding the concepts of proportionate treatment, unselfish donation by living persons, promotion of local institutions efficiency. PMID:20677677

  8. A novel bit-quad-based Euler number computing algorithm.

    PubMed

    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

  9. Modeling micro-electronics drill bit behavior with ABAQUS Standard

    SciTech Connect

    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.

  10. 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.

  11. 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.

  12. New Mechanisms of rock-bit wear in geothermal wells

    SciTech Connect

    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.

  13. Computationally efficient control allocation

    NASA Technical Reports Server (NTRS)

    Durham, Wayne (Inventor)

    2001-01-01

    A computationally efficient method for calculating near-optimal solutions to the three-objective, linear control allocation problem is disclosed. The control allocation problem is that of distributing the effort of redundant control effectors to achieve some desired set of objectives. The problem is deemed linear if control effectiveness is affine with respect to the individual control effectors. The optimal solution is that which exploits the collective maximum capability of the effectors within their individual physical limits. Computational efficiency is measured by the number of floating-point operations required for solution. The method presented returned optimal solutions in more than 90% of the cases examined; non-optimal solutions returned by the method were typically much less than 1% different from optimal and the errors tended to become smaller than 0.01% as the number of controls was increased. The magnitude of the errors returned by the present method was much smaller than those that resulted from either pseudo inverse or cascaded generalized inverse solutions. The computational complexity of the method presented varied linearly with increasing numbers of controls; the number of required floating point operations increased from 5.5 i, to seven times faster than did the minimum-norm solution (the pseudoinverse), and at about the same rate as did the cascaded generalized inverse solution. The computational requirements of the method presented were much better than that of previously described facet-searching methods which increase in proportion to the square of the number of controls.

  14. Popularity-aware rate allocation in multiview video

    NASA Astrophysics Data System (ADS)

    Fiandrotti, Attilio; Chakareski, Jacob; Frossard, Pascal

    2010-07-01

    We propose a framework for popularity-driven rate allocation in H.264/MVC-based multi-view video communications when the overall rate and the rate necessary for decoding each view are constrained in the delivery architecture. We formulate a rate allocation optimization problem that takes into account the popularity of each view among the client population and the rate-distortion characteristics of the multi-view sequence so that the performance of the system is maximized in terms of popularity-weighted average quality. We consider the cases where the global bit budget or the decoding rate of each view is constrained. We devise a simple ratevideo- quality model that accounts for the characteristics of interview prediction schemes typical of multi-view video. The video quality model is used for solving the rate allocation problem with the help of an interior point optimization method. We then show through experiments that the proposed rate allocation scheme clearly outperforms baseline solutions in terms of popularity-weighted video quality. In particular, we demonstrate that the joint knowledge of the rate-distortion characteristics of the video content, its coding dependencies, and the popularity factor of each view is key in achieving good coding performance in multi-view video systems.

  15. 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.

  16. Research on allocation efficiency of the daisy chain allocation algorithm

    NASA Astrophysics Data System (ADS)

    Shi, Jingping; Zhang, Weiguo

    2013-03-01

    With the improvement of the aircraft performance in reliability, maneuverability and survivability, the number of the control effectors increases a lot. How to distribute the three-axis moments into the control surfaces reasonably becomes an important problem. Daisy chain method is simple and easy to be carried out in the design of the allocation system. But it can not solve the allocation problem for entire attainable moment subset. For the lateral-directional allocation problem, the allocation efficiency of the daisy chain can be directly measured by the area of its subset of attainable moments. Because of the non-linear allocation characteristic, the subset of attainable moments of daisy-chain method is a complex non-convex polygon, and it is difficult to solve directly. By analyzing the two-dimensional allocation problems with a "micro-element" idea, a numerical calculation algorithm is proposed to compute the area of the non-convex polygon. In order to improve the allocation efficiency of the algorithm, a genetic algorithm with the allocation efficiency chosen as the fitness function is proposed to find the best pseudo-inverse matrix.

  17. Progress in the Advanced Synthetic-Diamond Drill Bit Program

    SciTech Connect

    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.

  18. Strategies for Model Reduction: Comparing Different Optimal Bases.

    NASA Astrophysics Data System (ADS)

    Crommelin, D. T.; Majda, A. J.

    2004-09-01

    Several different ways of constructing optimal bases for efficient dynamical modeling are compared: empirical orthogonal functions (EOFs), optimal persistence patterns (OPPs), and principal interaction patterns (PIPs). Past studies on fluid-dynamical topics have pointed out that EOF-based models can have difficulties reproducing behavior dominated by irregular transitions between different dynamical states. This issue is addressed in a geophysical context, by assessing the ability of these strategies for efficient dynamical modeling to reproduce the chaotic regime transitions in a simple atmosphere model. The atmosphere model is the well-known Charney DeVore model, a six-dimensional truncation of the equations describing barotropic flow over topography in a β-plane channel geometry. This model is able to generate regime transitions for well-chosen parameter settings. The models based on PIPs are found to be superior to the EOF- and OPP-based models, in spite of some undesirable sensitivities inherent to the PIP method.


  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Drag drill bit having improved arrangement of cutting elements

    SciTech Connect

    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.

  4. Development and testing of a Mudjet-augmented PDC bit.

    SciTech Connect

    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.

  5. 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.

  6. 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.

  7. Sealed and lubricated rock bit with air protected seal ring

    SciTech Connect

    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.

  8. Cooling system for cooling the bits of a cutting machine

    SciTech Connect

    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.

  9. New PDC bit design increased penetration rate in slim wells

    SciTech Connect

    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.

  10. PDC (polycrystalline diamond compact) bit research at Sandia National Laboratories

    SciTech Connect

    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.

  11. Core bit design reduces mud invasion, improves ROP

    SciTech Connect

    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.

  12. 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.

  13. 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.

  14. Improved seal for geothermal drill bit. Final technical report

    SciTech Connect

    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.

  15. 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.

  16. BitPredator: A Discovery Algorithm for BitTorrent Initial Seeders and Peers

    SciTech Connect

    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.

  17. High density bit transition requirements versus the effects on BCH error correcting code. [bit synchronization

    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.

  18. Experimental test of Landauer's principle in single-bit operations on nanomagnetic memory bits.

    PubMed

    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

  19. Experimental test of Landauer’s principle in single-bit operations on nanomagnetic memory bits

    PubMed Central

    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

  20. Collaborative Resource Allocation

    NASA Technical Reports Server (NTRS)

    Wang, Yeou-Fang; Wax, Allan; Lam, Raymond; Baldwin, John; Borden, Chester

    2007-01-01

    Collaborative Resource Allocation Networking Environment (CRANE) Version 0.5 is a prototype created to prove the newest concept of using a distributed environment to schedule Deep Space Network (DSN) antenna times in a collaborative fashion. This program is for all space-flight and terrestrial science project users and DSN schedulers to perform scheduling activities and conflict resolution, both synchronously and asynchronously. Project schedulers can, for the first time, participate directly in scheduling their tracking times into the official DSN schedule, and negotiate directly with other projects in an integrated scheduling system. A master schedule covers long-range, mid-range, near-real-time, and real-time scheduling time frames all in one, rather than the current method of separate functions that are supported by different processes and tools. CRANE also provides private workspaces (both dynamic and static), data sharing, scenario management, user control, rapid messaging (based on Java Message Service), data/time synchronization, workflow management, notification (including emails), conflict checking, and a linkage to a schedule generation engine. The data structure with corresponding database design combines object trees with multiple associated mortal instances and relational database to provide unprecedented traceability and simplify the existing DSN XML schedule representation. These technologies are used to provide traceability, schedule negotiation, conflict resolution, and load forecasting from real-time operations to long-range loading analysis up to 20 years in the future. CRANE includes a database, a stored procedure layer, an agent-based middle tier, a Web service wrapper, a Windows Integrated Analysis Environment (IAE), a Java application, and a Web page interface.

  1. 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.…

  2. TriBITS (Tribal Build, Integrate, and Test System)

    Energy Science and Technology Software Center (ESTSC)

    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.

  3. 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.

  4. 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.

  5. Continuous chain bit with downhole cycling capability

    DOEpatents

    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.

  6. Drill bit stud and method of manufacture

    SciTech Connect

    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.

  7. Single Abrikosov vortices as quantized information bits

    PubMed Central

    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

  8. Variable length three-cone rock bit nozzles

    SciTech Connect

    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.

  9. Uniqueness: skews bit occurrence frequencies in randomly generated fingerprint libraries.

    PubMed

    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

  10. 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.

  11. Evolution of a Hybrid Roller Cone/PDC core bit

    SciTech Connect

    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.

  12. Development of optimization-based probabilistic earthquake scenarios for the city of Tehran

    NASA Astrophysics Data System (ADS)

    Zolfaghari, M. R.; Peyghaleh, E.

    2016-01-01

    This paper presents the methodology and practical example for the application of optimization process to select earthquake scenarios which best represent probabilistic earthquake hazard in a given region. The method is based on simulation of a large dataset of potential earthquakes, representing the long-term seismotectonic characteristics in a given region. The simulation process uses Monte-Carlo simulation and regional seismogenic source parameters to generate a synthetic earthquake catalogue consisting of a large number of earthquakes, each characterized with magnitude, location, focal depth and fault characteristics. Such catalogue provides full distributions of events in time, space and size; however, demands large computation power when is used for risk assessment, particularly when other sources of uncertainties are involved in the process. To reduce the number of selected earthquake scenarios, a mixed-integer linear program formulation is developed in this study. This approach results in reduced set of optimization-based probabilistic earthquake scenario, while maintaining shape of hazard curves and full probabilistic picture by minimizing the error between hazard curves driven by full and reduced sets of synthetic earthquake scenarios. To test the model, the regional seismotectonic and seismogenic characteristics of northern Iran are used to simulate a set of 10,000-year worth of events consisting of some 84,000 earthquakes. The optimization model is then performed multiple times with various input data, taking into account probabilistic seismic hazard for Tehran city as the main constrains. The sensitivity of the selected scenarios to the user-specified site/return period error-weight is also assessed. The methodology could enhance run time process for full probabilistic earthquake studies like seismic hazard and risk assessment. The reduced set is the representative of the contributions of all possible earthquakes; however, it requires far less

  13. 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

  14. 24 CFR 92.50 - Formula allocation.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 24 Housing and Urban Development 1 2011-04-01 2011-04-01 false Formula allocation. 92.50 Section 92.50 Housing and Urban Development Office of the Secretary, Department of Housing and Urban Development HOME INVESTMENT PARTNERSHIPS PROGRAM Allocation Formula § 92.50 Formula allocation. (a) Jurisdictions eligible for a formula allocation. HUD...

  15. 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.

  16. 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.

  17. Earth boring bit with pressure compensating rigid face seal

    SciTech Connect

    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.

  18. Impact of bit performance on geothermal-well cost

    SciTech Connect

    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.

  19. Fitness Probability Distribution of Bit-Flip Mutation.

    PubMed

    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

  20. Collective credit allocation in science

    PubMed Central

    Shen, Hua-Wei; Barabási, Albert-László

    2014-01-01

    Collaboration among researchers is an essential component of the modern scientific enterprise, playing a particularly important role in multidisciplinary research. However, we continue to wrestle with allocating credit to the coauthors of publications with multiple authors, because the relative contribution of each author is difficult to determine. At the same time, the scientific community runs an informal field-dependent credit allocation process that assigns credit in a collective fashion to each work. Here we develop a credit allocation algorithm that captures the coauthors’ contribution to a publication as perceived by the scientific community, reproducing the informal collective credit allocation of science. We validate the method by identifying the authors of Nobel-winning papers that are credited for the discovery, independent of their positions in the author list. The method can also compare the relative impact of researchers working in the same field, even if they did not publish together. The ability to accurately measure the relative credit of researchers could affect many aspects of credit allocation in science, potentially impacting hiring, funding, and promotion decisions. PMID:25114238

  1. Secure self-calibrating quantum random-bit generator

    SciTech Connect

    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.

  2. 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.

  3. Bit selection increases coiled tubing and slimhole success

    SciTech Connect

    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.

  4. Experimental bit commitment based on quantum communication and special relativity.

    PubMed

    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

  5. Optimality Versus Resilience In Patterns Of Carbon Allocation Within Plants Under Climate Change

    NASA Astrophysics Data System (ADS)

    Srinivasan, V.; Kumar, P.; Sivapalan, M.

    2010-12-01

    Predicting the allocation of assimilated carbon among different parts within a plant under current and future climates is a challenging task that is of significant interest. Several empirical and mechanistic models have been developed over the years to solve for the carbon allocation within a plant and these have demonstrated limited success. This challenge is further exacerbated when we need to consider the issue of plant acclimation due to climate change. Optimality based carbon allocation models have the ability to provide a general framework and have been proposed to be a strong alternative to empirical and mechanistic models. While several optimality functions have been proposed, more recently the idea of optimizing end of life cycle reproductive biomass has been demonstrated to have significant success (Iwasa 2000). This optimality function unlike others is more fundamental as it is directly based on the concept of evolutionary fitness of each individual. We apply an optimality based carbon allocation model to the soybean ecosystem and other ecosystems and analyze the predictions. Our analysis demonstrates that plants have the capability to achieve a given end state using different allocation strategies during a growing season. More importantly, the soybean ecosystem exhibits significant suboptimal behavior, where the end of life cycle reproductive biomass realized through field measurements, is lower than the model predicted optimum. From these one can infer that in reality, plants allocate a relatively larger fraction of its carbon to leaf and root biomass and a relatively smaller fraction to reproductive biomass when compared to the model predicted optimal allocation pathway. This trend is also obtained while simulating acclimation behavior under elevated CO2 conditions simulating future climate scenarios. We hypothesize that plants in nature exhibit a significant degree of resilience that prevents them from following an optimal pathway resulting in a

  6. Strong no-go theorem for Gaussian quantum bit commitment

    SciTech Connect

    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.

  7. 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.

  8. 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.

  9. Tuned support for cutting elements in a drag bit

    SciTech Connect

    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.

  10. Drill-bit with full offset cutter bodies

    SciTech Connect

    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.

  11. 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.

  12. Task allocation among multiple intelligent robots

    NASA Technical Reports Server (NTRS)

    Gasser, L.; Bekey, G.

    1987-01-01

    Researchers describe the design of a decentralized mechanism for allocating assembly tasks in a multiple robot assembly workstation. Currently, the approach focuses on distributed allocation to explore its feasibility and its potential for adaptability to changing circumstances, rather than for optimizing throughput. Individual greedy robots make their own local allocation decisions using both dynamic allocation policies which propagate through a network of allocation goals, and local static and dynamic constraints describing which robots are elibible for which assembly tasks. Global coherence is achieved by proper weighting of allocation pressures propagating through the assembly plan. Deadlock avoidance and synchronization is achieved using periodic reassessments of local allocation decisions, ageing of allocation goals, and short-term allocation locks on goals.

  13. Regulating nutrient allocation in plants

    DOEpatents

    Udvardi, Michael; Yang, Jiading; Worley, Eric

    2014-12-09

    The invention provides coding and promoter sequences for a VS-1 and AP-2 gene, which affects the developmental process of senescence in plants. Vectors, transgenic plants, seeds, and host cells comprising heterologous VS-1 and AP-2 genes are also provided. Additionally provided are methods of altering nutrient allocation and composition in a plant using the VS-1 and AP-2 genes.

  14. Resource Allocation: A Participatory Process.

    ERIC Educational Resources Information Center

    Reid, Alban E.

    Whether a participatory process for resource allocation in a public community college setting occurs depends upon several key factors: (1) the leadership style of the institutional chief executive officer; (2) the administrative organizational structure of the institution; (3) the relationship which exists between and among members of the various…

  15. Report on Tribal Priority Allocations.

    ERIC Educational Resources Information Center

    Bureau of Indian Affairs (Dept. of Interior), Washington, DC.

    As part of Bureau of Indian Affairs (BIA) funding, Tribal Priority Allocations (TPA) are the principal source of funds for tribal governments and agency offices at the reservation level. According to their unique needs and circumstances, tribes may prioritize funding among eight general categories: government, human services, education, public…

  16. Administrators' Decisions about Resource Allocation

    ERIC Educational Resources Information Center

    Knight, William E.; Folkins, John W.; Hakel, Milton D.; Kennell, Richard P.

    2011-01-01

    Do academic administrators make decisions about resource allocation differently depending on the discipline receiving the funding? Does an administrator's academic identity influence these decisions? This study explored those questions with a sample of 1,690 academic administrators at doctoral-research universities. Participants used fictional…

  17. 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.

  18. 45 CFR 1355.57 - Cost allocation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 45 Public Welfare 4 2012-10-01 2012-10-01 false Cost allocation. 1355.57 Section 1355.57 Public... MAINTENANCE PAYMENTS, ADOPTION ASSISTANCE, AND CHILD AND FAMILY SERVICES GENERAL § 1355.57 Cost allocation. (a...) Cost allocation and distribution for the planning, design, development, installation and operation...

  19. 45 CFR 400.13 - Cost allocation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 45 Public Welfare 2 2013-10-01 2012-10-01 true Cost allocation. 400.13 Section 400.13 Public... for Refugee Resettlement Award of Grants to States § 400.13 Cost allocation. (a) A State must allocate... management of the State's refugee program (e.g., development of the State plan, overall program...

  20. 45 CFR 400.13 - Cost allocation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 45 Public Welfare 2 2012-10-01 2012-10-01 false Cost allocation. 400.13 Section 400.13 Public... for Refugee Resettlement Award of Grants to States § 400.13 Cost allocation. (a) A State must allocate... management of the State's refugee program (e.g., development of the State plan, overall program...

  1. 45 CFR 400.13 - Cost allocation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 2 2010-10-01 2010-10-01 false Cost allocation. 400.13 Section 400.13 Public... for Refugee Resettlement Award of Grants to States § 400.13 Cost allocation. (a) A State must allocate... management of the State's refugee program (e.g., development of the State plan, overall program...

  2. 45 CFR 400.13 - Cost allocation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 45 Public Welfare 2 2011-10-01 2011-10-01 false Cost allocation. 400.13 Section 400.13 Public... for Refugee Resettlement Award of Grants to States § 400.13 Cost allocation. (a) A State must allocate... management of the State's refugee program (e.g., development of the State plan, overall program...

  3. 45 CFR 1355.57 - Cost allocation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 45 Public Welfare 4 2011-10-01 2011-10-01 false Cost allocation. 1355.57 Section 1355.57 Public... MAINTENANCE PAYMENTS, ADOPTION ASSISTANCE, AND CHILD AND FAMILY SERVICES GENERAL § 1355.57 Cost allocation. (a... maintenance payments or adoption assistance payments may be made under the State plan. (b) Cost allocation...

  4. 24 CFR 92.50 - Formula allocation.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 24 Housing and Urban Development 1 2014-04-01 2014-04-01 false Formula allocation. 92.50 Section 92.50 Housing and Urban Development Office of the Secretary, Department of Housing and Urban Development HOME INVESTMENT PARTNERSHIPS PROGRAM Allocation Formula § 92.50 Formula allocation....

  5. 24 CFR 92.50 - Formula allocation.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 24 Housing and Urban Development 1 2013-04-01 2013-04-01 false Formula allocation. 92.50 Section 92.50 Housing and Urban Development Office of the Secretary, Department of Housing and Urban Development HOME INVESTMENT PARTNERSHIPS PROGRAM Allocation Formula § 92.50 Formula allocation....

  6. 24 CFR 92.50 - Formula allocation.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 24 Housing and Urban Development 1 2012-04-01 2012-04-01 false Formula allocation. 92.50 Section 92.50 Housing and Urban Development Office of the Secretary, Department of Housing and Urban Development HOME INVESTMENT PARTNERSHIPS PROGRAM Allocation Formula § 92.50 Formula allocation....

  7. 23 CFR 660.107 - Allocations.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 23 Highways 1 2010-04-01 2010-04-01 false Allocations. 660.107 Section 660.107 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS SPECIAL PROGRAMS (DIRECT FEDERAL) Forest Highways § 660.107 Allocations. On October 1 of each fiscal year, the FHWA will allocate 66 percent of Public Lands...

  8. 15 CFR 923.110 - Allocation formula.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 15 Commerce and Foreign Trade 3 2010-01-01 2010-01-01 false Allocation formula. 923.110 Section... Grants § 923.110 Allocation formula. (a) As required by subsection 306(a), the Secretary may make grants...) Allocation formula factors and weighting. Each State eligible to receive a financial assistance award...

  9. 10 CFR 455.31 - Allocation formulas.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 3 2010-01-01 2010-01-01 false Allocation formulas. 455.31 Section 455.31 Energy... § 455.31 Allocation formulas. (a) Financial assistance for conducting technical assistance programs for... this section. (c) The allocation factor (K) shall be determined by the formula: EC14NO91.086 where,...

  10. 24 CFR 574.130 - Formula allocations.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 24 Housing and Urban Development 3 2010-04-01 2010-04-01 false Formula allocations. 574.130... URBAN DEVELOPMENT COMMUNITY FACILITIES HOUSING OPPORTUNITIES FOR PERSONS WITH AIDS Formula Entitlements § 574.130 Formula allocations. (a) Data sources. HUD will allocate funds based on the number of cases...

  11. 45 CFR 1355.57 - Cost allocation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 4 2010-10-01 2010-10-01 false Cost allocation. 1355.57 Section 1355.57 Public... MAINTENANCE PAYMENTS, ADOPTION ASSISTANCE, AND CHILD AND FAMILY SERVICES GENERAL § 1355.57 Cost allocation. (a... maintenance payments or adoption assistance payments may be made under the State plan. (b) Cost allocation...

  12. 45 CFR 98.55 - Cost allocation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 45 Public Welfare 1 2014-10-01 2014-10-01 false Cost allocation. 98.55 Section 98.55 Public... of Child Care and Development Funds § 98.55 Cost allocation. (a) The Lead Agency and subgrantees shall keep on file cost allocation plans or indirect cost agreements, as appropriate, that have...

  13. 45 CFR 98.55 - Cost allocation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 45 Public Welfare 1 2011-10-01 2011-10-01 false Cost allocation. 98.55 Section 98.55 Public... of Child Care and Development Funds § 98.55 Cost allocation. (a) The Lead Agency and subgrantees shall keep on file cost allocation plans or indirect cost agreements, as appropriate, that have...

  14. Communication patterns and allocation strategies.

    SciTech Connect

    Leung, Vitus Joseph; Mache, Jens Wolfgang; Bunde, David P.

    2004-01-01

    Motivated by observations about job runtimes on the CPlant system, we use a trace-driven microsimulator to begin characterizing the performance of different classes of allocation algorithms on jobs with different communication patterns in space-shared parallel systems with mesh topology. We show that relative performance varies considerably with communication pattern. The Paging strategy using the Hilbert space-filling curve and the Best Fit heuristic performed best across several communication patterns.

  15. Minority Transportation Expenditure Allocation Model

    Energy Science and Technology Software Center (ESTSC)

    1993-04-12

    MITRAM (Minority TRansportation expenditure Allocation Model) can project various transportation related attributes of minority (Black and Hispanic) and majority (white) populations. The model projects vehicle ownership, vehicle miles of travel, workers, new car and on-road fleet fuel economy, amount and share of household income spent on gasoline, and household expenditures on public transportation and taxis. MITRAM predicts reactions to sustained fuel price changes for up to 10 years after the change.

  16. Security bound of cheat sensitive quantum bit commitment.

    PubMed

    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

  17. Fully photonics-based physical random bit generator.

    PubMed

    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

  18. Security bound of cheat sensitive quantum bit commitment

    PubMed Central

    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

  19. New bits, motors improve economics of slim hole horizontal wells

    SciTech Connect

    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.

  20. Unconditionally secure bit commitment by transmitting measurement outcomes.

    PubMed

    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

  1. 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.

  2. 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.

  3. 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.

  4. Bit-related lesions in Icelandic competition horses

    PubMed Central

    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

  5. Use of single-cutter data in the analysis of PDC bit designs

    SciTech Connect

    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.

  6. 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.

  7. Demonstration of low-power bit-interleaving TDM PON.

    PubMed

    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

  8. Hanford coring bit temperature monitor development testing results report

    SciTech Connect

    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.

  9. Cloning the entanglement of a pair of quantum bits

    SciTech Connect

    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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. Development of a jet-assisted polycrystalline diamond drill bit

    SciTech Connect

    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.

  15. Allocating Variability and Reserve Requirements (Presentation)

    SciTech Connect

    Kirby, B.; King, J.; Milligan, M.

    2011-10-01

    This presentation describes how you could conceivably allocate variability and reserve requirements, including how to allocate aggregation benefits. Conclusions of this presentation are: (1) Aggregation provides benefits because individual requirements are not 100% correlated; (2) Method needed to allocate reduced requirement among participants; (3) Differences between allocation results are subtle - (a) Not immediately obvious which method is 'better'; (b) Many are numerically 'correct', they sum to the physical requirement; (c) Many are not 'fair', Results depend on sub-aggregation and/or the order individuals are included; and (4) Vector allocation method is simple and fair.

  16. 45 CFR 402.31 - Determination of allocations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... ASSISTANCE GRANTS State Allocations § 402.31 Determination of allocations. (a) Allocation formula. Allocations will be computed according to a formula using the following factors and weights: (1) 50...

  17. 45 CFR 402.31 - Determination of allocations.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... State Allocations § 402.31 Determination of allocations. (a) Allocation formula. Allocations will be computed according to a formula using the following factors and weights: (1) 50 percent based on the...

  18. Bit-rate-variable and order-switchable optical multiplexing of high-speed pseudorandom bit sequence using optical delays.

    PubMed

    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

  19. 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.

  20. 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.

  1. A radiation-hardened 16/32-bit microprocessor

    SciTech Connect

    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.

  2. 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.

  3. 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.

  4. 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.

  5. 16. STRUCTURAL DETAILS: CHANNEL, BIT & CLEAT, ANCHOR BOLTS & ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    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

  6. 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.

  7. Investigation of optimization-based reconstruction with an image-total-variation constraint in PET.

    PubMed

    Zhang, Zheng; Ye, Jinghan; Chen, Buxin; Perkins, Amy E; Rose, Sean; Sidky, Emil Y; Kao, Chien-Min; Xia, Dan; Tung, Chi-Hua; Pan, Xiaochuan

    2016-08-21

    Interest remains in reconstruction-algorithm research and development for possible improvement of image quality in current PET imaging and for enabling innovative PET systems to enhance existing, and facilitate new, preclinical and clinical applications. Optimization-based image reconstruction has been demonstrated in recent years of potential utility for CT imaging applications. In this work, we investigate tailoring the optimization-based techniques to image reconstruction for PET systems with standard and non-standard scan configurations. Specifically, given an image-total-variation (TV) constraint, we investigated how the selection of different data divergences and associated parameters impacts the optimization-based reconstruction of PET images. The reconstruction robustness was explored also with respect to different data conditions and activity up-takes of practical relevance. A study was conducted particularly for image reconstruction from data collected by use of a PET configuration with sparsely populated detectors. Overall, the study demonstrates the robustness of the TV-constrained, optimization-based reconstruction for considerably different data conditions in PET imaging, as well as its potential to enable PET configurations with reduced numbers of detectors. Insights gained in the study may be exploited for developing algorithms for PET-image reconstruction and for enabling PET-configuration design of practical usefulness in preclinical and clinical applications. PMID:27452653

  8. Nodal Analysis Optimization Based on the Use of Virtual Current Sources: A Powerful New Pedagogical Method

    ERIC Educational Resources Information Center

    Chatzarakis, G. E.

    2009-01-01

    This paper presents a new pedagogical method for nodal analysis optimization based on the use of virtual current sources, applicable to any linear electric circuit (LEC), regardless of its complexity. The proposed method leads to straightforward solutions, mostly arrived at by inspection. Furthermore, the method is easily adapted to computer…

  9. A method for investigating system matrix properties in optimization-based CT reconstruction

    NASA Astrophysics Data System (ADS)

    Rose, Sean D.; Sidky, Emil Y.; Pan, Xiaochuan

    2016-04-01

    Optimization-based iterative reconstruction methods have shown much promise for a variety of applications in X-ray computed tomography (CT). In these reconstruction methods, the X-ray measurement is modeled as a linear mapping from a finite-dimensional image space to a finite dimensional data-space. This mapping is dependent on a number of factors including the basis functions used for image representation1 and the method by which the matrix representing this mapping is generated.2 Understanding the properties of this linear mapping and how it depends on our choice of parameters is fundamental to optimization-based reconstruction. In this work, we confine our attention to a pixel basis and propose a method to investigate the effect of pixel size in optimization-based reconstruction. The proposed method provides insight into the tradeoff between higher resolution image representation and matrix conditioning. We demonstrate this method for a particular breast CT system geometry. We find that the images obtained from accurate solution of a least squares reconstruction optimization problem have high sensitivity to pixel size within certain regimes. We propose two methods by which this sensitivity can be reduced and demonstrate their efficacy. Our results indicate that the choice of pixel size in optimization-based reconstruction can have great impact on the quality of the reconstructed image, and that understanding the properties of the linear mapping modeling the X-ray measurement can help guide us with this choice.

  10. Investigation of optimization-based reconstruction with an image-total-variation constraint in PET

    NASA Astrophysics Data System (ADS)

    Zhang, Zheng; Ye, Jinghan; Chen, Buxin; Perkins, Amy E.; Rose, Sean; Sidky, Emil Y.; Kao, Chien-Min; Xia, Dan; Tung, Chi-Hua; Pan, Xiaochuan

    2016-08-01

    Interest remains in reconstruction-algorithm research and development for possible improvement of image quality in current PET imaging and for enabling innovative PET systems to enhance existing, and facilitate new, preclinical and clinical applications. Optimization-based image reconstruction has been demonstrated in recent years of potential utility for CT imaging applications. In this work, we investigate tailoring the optimization-based techniques to image reconstruction for PET systems with standard and non-standard scan configurations. Specifically, given an image-total-variation (TV) constraint, we investigated how the selection of different data divergences and associated parameters impacts the optimization-based reconstruction of PET images. The reconstruction robustness was explored also with respect to different data conditions and activity up-takes of practical relevance. A study was conducted particularly for image reconstruction from data collected by use of a PET configuration with sparsely populated detectors. Overall, the study demonstrates the robustness of the TV-constrained, optimization-based reconstruction for considerably different data conditions in PET imaging, as well as its potential to enable PET configurations with reduced numbers of detectors. Insights gained in the study may be exploited for developing algorithms for PET-image reconstruction and for enabling PET-configuration design of practical usefulness in preclinical and clinical applications.