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.     

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.     

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.     

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.     

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.     

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     

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.     

A new scheme for processing output data from resonant gravitational antennas

A new scheme is proposed for measuring the noise parameters in the primary processing of the output signal from a resonant gravitational antenna working with fast filtration. Translated from Izmeritel'naya Tekhnika, No. 9, pp. 19–22, September, 2008.     

Optimized forward model and retrieval scheme for MIPAS near-real-time data processing

An optimized code to perform the near-real-time retrieval of profiles of pressure, temperature, and volume mixing ratio (VMR) of five key species (O(3), H(2)O, HNO(3), CH(4), and N(2)O) from infrared limb spectra recorded by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) experiment on board the European Space Agency (ESA) Environmental Satellite ENVISAT-1 was developed as part of a ESA-supported study. The implementation uses the global fit approach on selected narrow spectral intervals (microwindows) to retrieve each profile in sequence. The trade-off between run time and accuracy of the retrieval was optimized from both the physical and the mathematical points of view, with optimizations in the program structure, in the radiative transfer model, and in the computation of the retrieval Jacobian. The attained performances of the retrieval code are noise error on temperature <2 K at all the altitudes covered by the typical MIPAS scan (8-53 km with 3-km resolution), noise error on tangent pressure <3%, and noise error on VMR of the target species <5% at most of the altitudes covered by the standard MIPAS scan, with a total run time of less than 1 min on a modern workstation.     

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.     

Sparse partial least-squares regression and its applications to high-throughput data analysis

The partial least-squares (PLS) method is designed for prediction problems where the number of predictors is larger than the number of training samples. PLS is based on latent components that are linear combinations of all of the original predictors, so it automatically employs all predictors regardless of their relevance. This will potentially compromise its performance, but it will also make it difficult to interpret the result. In this paper, we propose a new formulation of the sparse PLS (SPLS) procedure to allow both sparse variable selection and dimension reduction. We use the standard L₁-penalty and the unbounded penalty of [1]. We develop a computing algorithm for SPLS by modifying the nonlinear iterative partial least-squares (NIPALS) algorithm, and illustrate the method with an analysis of a cancer dataset. Through the numerical studies we find that our SPLS method generally performs better than the standard PLS and other existing methods in variable selection and prediction.