A combinatorial characterization scheme for high-throughput investigations of hydrogen storage materials

In order to increase measurement throughput, a characterization scheme has been developed that accurately measures the hydrogen storage properties of materials in quantities ranging from 10 ng to 1 g. Initial identification of promising materials is realized by rapidly screening thin-film composition spread and thickness wedge samples using normalized IR emissivity imaging. The hydrogen storage properties of promising samples are confirmed through measurements on single-composition films with high-sensitivity (resolution <0.3 μg) Sievert’s-type apparatus. For selected samples, larger quantities of up to ∼100 mg may be prepared and their (de)hydrogenation and micro-structural properties probed via parallel in situ Raman spectroscopy. Final confirmation of the hydrogen storage properties is obtained on ∼1 g powder samples using a combined Raman spectroscopy/Sievert’s apparatus.     

A combinatorial characterization scheme for high-throughput investigations of hydrogen storage materials

Abstract

In order to increase measurement throughput, a characterization scheme has been developed that accurately measures the hydrogen storage properties of materials in quantities ranging from 10 ng to 1 g. Initial identification of promising materials is realized by rapidly screening thin-film composition spread and thickness wedge samples using normalized IR emissivity imaging. The hydrogen storage properties of promising samples are confirmed through measurements on single-composition films with high-sensitivity (resolution <0.3 μg) Sievert’s-type apparatus. For selected samples, larger quantities of up to ～100 mg may be prepared and their (de)hydrogenation and micro-structural properties probed via parallel in situ Raman spectroscopy. Final confirmation of the hydrogen storage properties is obtained on ～1 g powder samples using a combined Raman spectroscopy/Sievert’s apparatus.     

一种基于节目流行度的自适应流调度方案

提出了一种基于节目流行度的自适应流调度方案。该方案根据节目点播请求的强度自适应地调整分配给节目的信道数和带宽,并给出了在信道数改变过程中如何实现信道平滑过渡的方法。该方案综合了周期广播算法和流合并算法的优点。实验表明,采用此方案,在点播请求很少时能获得同流分并算法（如补丁算法）一样的性能,在点播请求很多时又有和周期广播算法一样少的服务带宽要求。     

Encrypted holographic data storage based on orthogonal-phase-code multiplexing

We describe an encrypted holographic data-storage system that combines orthogonal-phase-code multiplexing with a random-phase key. The system offers the security advantages of random-phase coding but retains the low cross-talk performance and the minimum code storage requirements typical in an orthogonal-phase-code-multiplexing system.     

Concatenated peak-to-average power ratio reduction scheme with threshold limited selection for coded orthogonal frequency-division multiplexing

The authors propose a concatenated scheme to reduce the peak-to-average power ratio (PAPR) in coded orthogonal frequency-division multiplexing (OFDM) systems. First, they employ a label-bits-inserted encoder of a random-like code to achieve selected mapping (SLM). Then they set a threshold at the selector to limit the number of candidate sequences. Both analytical and numerical results show that the complexity of the SLM implemented by the label-bit-inserted encoder can be significantly reduced by threshold limited selection. With the same complexity, the performance of PAPR reduction is improved. The proposed concatenated PAPR reduction scheme enjoys many advantages including low-complexity, small overhead, no side information transmission and no performance loss or additional complexity at the receiver.     

Organizational scheme for corrosion-fatigue crack propagation data

A model, proposed earlier, is modified in an attempt to explain a number of curious behaviors of corrosion-fatigue crack propagation (CFCP). The behaviors include effects of load ratio R in air and salt water vs vacuum, and effects of loading frequency at fixed R in these environments. Assumptions of the modeling are reviewed in detail in view of earlier objections to them. The ingredients of CFCP per this model: Poisson contraction, strain hardening, ligament surface attack/annihilation, and stress relaxation are developed and related to conditions of the crack tip locale. In the modeling, a parameter G, for growth rate factor, is developed solely as a function of the form of the ordinary or of the cyclic stress-strain curve. Previous work had developed a G₁ for the ordinary curve, to be associated with the surface attack effect as in stress-corrosion cracking, and one G₂ for the cyclic curve, to be associated with the stress relaxation effect as in fatigue crack propagation (FCP). A hybrid $\text{G}{}_{\mathrm{<mtext>2</mtext><mtext>1</mtext>}}$ is developed, combining attributes of both, which seems to successfully describe the corrosion induced augmentation of G₂. Parametric curves of $\text{G}{}_{\mathrm{<mtext>2</mtext><mtext>1</mtext>}}\text{(+G}{}_2\text{)}$ correspond well with stage II frequency-dependent growth in CFCP. However, alone they do not explain the frequency-wise stage II threshold shift nor the frequency-independent air-environment FCP rate. It is found that these trends can be represented by loci of constant plastic strain rate, due to crack loading and propagation, relative to the surface annihilation rate. Such loci are determined by comparing growth rate factor maps with strain rate maps, using parametric curves of equal geometric-series spacing. Maps of this sort are used to analyze about a dozen cases of CFCP including two titanium alloys and three steels, with one of the steels of four different tempers. Stress-strain curves of the low strength steels are processed to remove the Lüder band effect to facilitate the modeling. The scheme for data organization involves a representation of indexes of the two kinds of parametric curves fitting the data, and the process zone size implied by the fitting. Model predication of load-ratio effects on the fatigue crack growth threshold is in good correspondence with literature data. Comparison of estimated process zone sizes with literature data of microstructural and fractographic size measurements is encouraging.     

Single-beam data encoding using a holographic angular multiplexing technique

We propose a novel configuration for angular multiplexing holographic encoding in which the signal beam and the reference beam are combined into a single beam. By using a spatial light modulator based on twisted nematic liquid crystals, the signal and the reference beams are modulated in amplitude mode and phase mode, respectively. The multiplexed interference patterns with the reference beams of different incident angles are recorded near the Fourier transform plane, and then the signals are selectively reconstructed by the corresponding reference beam. Both the simulation and the experiment of single-beam angular multiplexed holography are performed with consistent results. Compared with the traditional angular multiplexing holographic recording system, the single-beam configuration is more compact, easier to adjust, and less sensitive to the vibration of the environment. Therefore, it will be more attractive for potential applications in many fields, such as high-density signal recording and data encryption.     

Spatial depth-based classification for functional data

We enlarge the number of available functional depths by introducing the kernelized functional spatial depth (KFSD). KFSD is a local-oriented and kernel-based version of the recently proposed functional spatial depth (FSD) that may be useful for studying functional samples that require an analysis at a local level. In addition, we consider supervised functional classification problems, focusing on cases in which the differences between groups are not extremely clear-cut or the data may contain outlying curves. We perform classification by means of some available robust methods that involve the use of a given functional depth, including FSD and KFSD, among others. We use the functional k-nearest neighbor classifier as a benchmark procedure. The results of a simulation study indicate that the KFSD-based classification approach leads to good results. Finally, we consider two real classification problems, obtaining results that are consistent with the findings observed with simulated curves.     

面向数据流的敏感规则k-匿名保护算法

为了使攻击者通过降低阈值来发现被隐藏规则的概率小于1/k,以此实现对敏感规则的二重保护,提出了一种面向数据流的敏感规则k-匿名保护算法.该算法首先用时间滑动窗口技术来获取数据使用者最感兴趣的最新n个时刻到达的数据,然后通过追加交易的方式而并非修改交易项的方式来实现对敏感规则的k-匿名,从而避免对数据流的二次访问以及被隐藏敏感规则的泄漏.同时采用素数编码的方法,用素数集代替原始项集参与运算,以提高算法的效率和降低算法的空间复杂度.实验结果表明,此算法可以在数据流环境下高效进行敏感规则的k-匿名,并且能够保证挖掘结果的有用性.     

基于补丁流传输机制的移动流媒体系统的缓存替换算法

介绍了在WCDMA网络中基于代理的移动流媒体系统的网络结构和特殊特征,给出了评价其中代理服务器缓存替换算法性能的平均传输成本和平均播放启动延迟这两个指标,推导出了在移动补丁流(MPatching)传输机制下与这些指标相对应的收益的计算公式,提出了适用于移动流媒体系统的基于收益的缓存替换算法.仿真结果表明,这种算法与传统的替换算法相比,具有更小的网络传输成本、播放启动延迟和更大的字节命中率,可显著提高移动流媒体系统的性能.     

Comparison of peristrophic multiplexing and a combination of angular and peristrophic holographic multiplexing in a thick PVA/acrylamide photopolymer for data storage

Two different types of multiplexing are used to store 90 holograms at the same location in a polyvinyl alcoholacrylamide photopolymer material. In the first, the 90 holograms are stored using only peristrophic multiplexing, whereas in the second a combination of angular and peristrophic multiplexing is used. The results (diffraction efficiency and dynamic range, M#) obtained with these two multiplexing techniques are compared. With the first, the dynamic range was M# = 13 and with the second M# = 8. An exposure schedule method is used to calculate the exposure time necessary to store the holograms with a more uniform, higher diffraction efficiency.     

Optimal traffic data archive scheme

An optimal traffic data archive scheme where the maximum information of the original data can be preserved using less storage space has been described. Compared with traditional equal-width methods where compact data are obtained by aggregating source data at fixed intervals, the optimal scheme uses varying intervals to aggregate data at different levels based on the variations within the source data. The resultant scheme is optimal in terms of information conservation, that is, the errors between the source data and the optimal compact data are the smallest. Operational traffic data have been used to test three proposed optimisation schemes: single-variable, multi-variable and heuristic schemes. It was found that, compared with traditional equal-width schemes, the size of the archived data can be reduced by six times if the single-variable optimisation scheme, or by three times if the multi-variable optimisation scheme is employed. The heuristic scheme using a combination of single-variable and multi-variable optimisations can then reduce storage space by three to six times     

逆向工程中三维离散点云的平滑整定新算法

 目前逆向工程中关于三维数据的平滑整定一般都是建立在三维数据之间的拓扑关系上的.提出一种平滑整定新算法,该算法是针对散乱、无序的,没有任何拓扑关系的三维离散点云数据.根据概率统计学中的频数法从大量的离散三维数据点云中找到噪声点,然后基于三维数据点云所建立的K-D树空间数据结构,找到噪声点周围的k个最近点,根据噪声点周边k个最近点的信息对噪声点处的真实信息进行恢复.基于激光三维平面扫描机器人系统证明该算法对离散三维数据点云的平滑整定的效果是令人满意的,在逆向工程中对数据预处理是切实可行的.     

A stream function implicit finite difference scheme for 2D incompressible flows of Newtonian fluids

The development of a new algorithm to solve the Navier–Stokes equations by an implicit formulation for the finite difference method is presented, that can be used to solve two‐dimensional incompressible flows by formulating the problem in terms of only one variable, the stream function. Two algebraic equations with 11 unknowns are obtained from the discretized mathematical model through the ADI method. An original algorithm is developed which allows a reduction from the original 11 unknowns to five and the use of the Pentadiagonal Matrix Algorithm (PDMA) in each one of the equations. An iterative cycle of calculations is implemented to assess the accuracy and speed of convergence of the algorithm. The relaxation parameter required is analytically obtained in terms of the size of the grid and the value of the Reynolds number by imposing the diagonal dominancy condition in the resulting pentadiagonal matrixes. The algorithm developed is tested by solving two classical steady fluid mechanics problems: cavity‐driven flow with Re=100, 400 and 1000 and flow in a sudden expansion with expansion ratio H/h=2 and Re=50, 100 and 200. The results obtained for the stream function are compared with values obtained by different available numerical methods, to evaluate the accuracy and the CPU time required by the proposed algorithm. Copyright © 2002 John Wiley & Sons, Ltd.     

Two-dimensional multiplexing scheme both with ring radius and topological charge of perfect optical vortex beam

Perfect optical vortex (POV) beam is a special kind of vortex beam, whose radius is independent of its topological charge. In this paper, we propose a two-dimensional multiplexing scheme with a ring radius and topological charge of POV beam. A communication system using the proposed multiplexing scheme with a two-step detection method is presented, and on–off keying modulation is applied to demonstrate the bit error rate (BER) performance under atmospheric turbulence. The numerical results show that the BER performance of the proposed scheme is better than that when only topological charge is multiplexed with the same conditions. The two-dimensional multiplexing scheme has an anti-interference capability since the ring radius is only concerned in magnitude. At the same time, the capacity and the spectral efficiency of the system are improved since both ring radial and topological charge of POV beam are used.     

RS485总线时分复用实现地震数据并行同步采集

为解决数字垂直地震剖面(vertical seismic profilingr,VSP)系统中各采集节点间同步性差、布线复杂等问题,提出一种基于RS485总线时分复用技术实现地震数据并行同步采集的设计方案。方案中各采集节点均并行挂接在RS485总线上,选择RS485的通信B线作为同步信号线,将其与各采集节点的控制器中断口相连接。数据采集时,首先将同步采集指令通过通信B线以广播方式发送到各采集节点,实现各节点同时启动ADC转换,然后通过RS485总线将采集的数据传送到采集站,最后由采集站通过以太网将数据传送到上位机,实现地震数据的并行同步采集。实际应用表明:该方案不仅提高采集节点间的同步性,还提高系统的可靠性,同时也减少系统布线。     

Two-stage modified signed-digit optical computing by spatial data encoding and polarization multiplexing

We propose and demonstrate an effective two-stage modified signed-digit optical computing technique (in contrast to previous three-stage techniques) based on spatial data encoding, polarization multiplexing, and multiple imaging. Our proposed reduction in operation stages requires a reference operation in addition to the transformation and weight operations common to three-stage systems. In our system's first stage a transformation (or weight) operation and a reference operation are implemented in parallel by use of four distinct polarization-multiplexed kernel operations. In the second stage the final desired result (e.g., addition and subtraction) and its complement are obtained in parallel with a single kernel operation. The operation speed of our two-stage modified signed-digit computing method is 33% faster than previous three-stage modified signed-digit algorithms.     

Encoding scheme for data storage and retrieval on DNA computers

There has been exponential growth in the amount of data being generated on a daily basis. Such a huge amount of data creates a need for efficient data storage techniques. Due to the limitations of existing storage media, new storage solutions have always been of interest. There have been recent developments in order to efficiently use synthetic deoxyribonucleic acid (DNA) for information storage. DNA storage has attracted researchers because of its extremely high data storage density, about 1 exabyte/mm³ and long life under easily achievable conditions. This work presents an encoding scheme for DNA‐based data storage system with controllable redundancy and reliability, the authors have also talked about the feasibility of the proposed method. The authors have also analysed the proposed algorithm for time and space complexity. The proposed encoding scheme tries to minimise the bases per letter ratio while controlling the redundancy. They have experimented with three different types of data with a value of redundancy as 0.75. In the randomised simulation setup, it was observed that the proposed algorithm was able to correctly retrieve the stored data in our experiments about 94% of the time. In the situation, where redundancy was increased to 1, the authors were able to retrieve all the information correctly in the proposed experiments.Inspec keywords: DNA, computational complexity, digital storage, storage media, biocomputingOther keywords: encoding scheme, DNA computers, exponential growth, storage media, synthetic deoxyribonucleic acid, information storage, extremely high data storage density, DNA‐based data storage system, controllable redundancy, stored data     

Logical scheme improvement for maintaining replicated data in distributed environment

Abstract

Data can be replicated to improve availability and performance in a distributed environment. To ensure the consistency of the replicated data, many schemes have been proposed. Most of these schemes are designed based on the quorum set approach. However, some of them are dominated. Such schemes can be further improved. By using theoretical analysis, we devise a paradigm for refining quorum schemes for managing replicated data. We present two dominating alternatives to a recently proposed high performance scheme.     

Phasing diffraction data from a stream of hydrated proteins

We consider the problem of phase determination for continuous diffraction patterns obtained from a beam of identical, aligned large molecules (such as proteins), each coated with a layer of water or vitreous ice. Many laser-aligned molecules are assumed to lie within a wide continuous x-ray beam at any instant. An iterative phasing method is developed to extract the common target structure in three dimensions from diffraction patterns of these doped ice balls. Several measurements of the diffraction intensity in reciprocal space are needed. We found iteratively two boundaries (supports) (between protein and ice and the outer iceball support) by using the charge-flipping and multiple hybrid input-output algorithms, working with multiple sets of measured data. The approach is applied to simulated data from hydrated lysozyme proteins generated by the serial crystallography method of laser-aligned protein-beam diffraction proposed by Spence and Doak [Phys. Rev. Lett. 92, 198102 (2004)]. We consider also the effect of empty ice balls on the patterns. The algorithm can also be used to align images with different randomly chosen origins, so that the same embedded subunits overlap.