Search

Recently, several novel isoreticular metal-organic framework (IRMOF) structures have been fabricated and tested for hydrogen storage applications. To improve our understanding of these materials, and to promote quantitative calculations and simulations, the binding energies of hydrogen molecules to the MOF have been studied. High-quality second-order Mo\ller–Plesset (MP2) calculations using the resolution of the identity approximation and the quadruple zeta QZVPP basis set were used. These calculations use terminated molecular fragments from the MOF materials. For H2 on the zinc oxide corners, the MP2 binding energy using Zn4O(HCO2)6 molecule is 6.28 kJ/mol. For H2 on the linkers, the binding energy is calculated using lithium-terminated molecular fragments. The MP2 results with coupled-cluster singles and doubles and noniterative triples method corrections and charge-transfer corrections are 4.16 kJ/mol for IRMOF-1, 4.72 kJ/mol for IRMOF-3, 4.86 kJ/mol for IRMOF-6, 4.54 kJ/mol for IRMOF-8, 5.50 and 4.90 kJ/mol for IRMOF-12, 4.87 and 4.84 kJ/mol for IRMOF-14, 5.42 kJ/mol for IRMOF-18, and 4.97 and 4.66 kJ/mol for IRMOF-993. The larger linkers are all able to bind multiple hydrogen molecules per side. The linkers of IRMOF-12, IRMOF-993, and IRMOF-14 can bind two to three, three, and four hydrogen molecules per side, respectively. In general, the larger linkers have the largest binding energies, and, together with the enhanced surface area available for binding, will provide increased hydrogen storage. We also find that adding up NH2 or CH3 groups to each linker can provide up to a 33% increase in the binding energy. [ABSTRACT FROM AUTHOR]

MnBi is of high interest for application as active layer in magneto-optic data storage media for several decades. Here the molecular-beam-epitaxy growth of Mn-Bi films on Si(111) surfaces is investigated under ultrahigh vacuum conditions by means of reflection high-energy electron diffraction, low-energy electron diffraction with spot-profile analysis, Auger-electron spectroscopy, magneto-optic Kerr spectroscopy, and transmission electron microscopy to reveal the microscopic film structure, film composition, and magnetic properties. The film parameters and growth protocols are varied but none of the chosen conditions lead to the formation of MnBi from the two elements. The affinity of Mn to the substrate material Si must be regarded as major reason for the fact that no MnBi forms. [ABSTRACT FROM AUTHOR]

This research with the main goal of cost reduction in the hard disk drive industry focused on the head stack assembly process is action research between university research teams and industry. It aims to study the head stack assembly process and to investigate the problems that need to be solved in order to reduce costs by using computer simulations and optimizations. Steps in simulation methodology were applied starting from data collection, model building, model verification, model validation, experimentation, and optimization. Several factors and their effects were investigated that could lead to production improvement of 7.94% increase in numbers of assembled head stack or 7.32% decrease in production cycle time. This paper demonstrates simulation optimization methodology applied to problem solving. Also it illustrates the successful case of using simulation optimization in cost reduction. [ABSTRACT FROM AUTHOR]

In this paper we discuss two types of complex tapered waveguides that can be used for heat-assisted magnetic recording (HAMR) applications. HAMR is an emerging technique in the hard disk drive (HDD) industry that enables nano-scale magnetic recording. It requires the use of a laser beam to define magnetic recording features, where the size and profile of delivered optical spot is critical for this technique. In this work, we first show that traditional tapered waveguide and some reported advanced designs do not work well for the case of HAMR. Then we demonstrate with simulation results that specially designed tapered waveguides can deliver highly focused optical beam for use in HAMR systems. At the same time, the proposed waveguide structures can be realized with conventional industry top down fabrication process, which facilitates the integration of such structures with conventional magnetic head industry manufacturing at low cost. [ABSTRACT FROM AUTHOR]

Flash is a type of Electronically Erasable Programmable Read-Only Memory (EEPROM). Different from traditional magnetic disks, flash memories have no moving parts and are purely electronic devices, giving them unique advantages, such as lower access latency, lower power consumption, higher density, shock resistance, and lack of noise. However, existing applications cannot run directly on flash memories due to their special characteristics. Flash Translation Layer (FTL) is a software layer built on raw flash memories that emulates a normal block device like magnetic disks. Primary functionalities of the FTL include address translation, garbage collection, and wear leveling. This survey focuses on address translation technologies and provides a broad overview of existing schemes described in patents, journals, and conference proceedings. [ABSTRACT FROM AUTHOR]

Data provenance allows scientists to validate their model as well as to investigate the origin of an unexpected value. Furthermore, it can be used as a replication recipe for output data products. However, capturing provenance requires enormous effort by scientists in terms of time and training. First, they need to design the workflow of the scientific model, i.e., workflow provenance, which requires both time and training. However, in practice, scientists may not document any workflow provenance before the model execution due to the lack of time and training. Second, they need to capture provenance while the model is running, i.e., fine-grained data provenance. Explicit documentation of fine-grained provenance is not feasible because of the massive storage consumption by provenance data in the applications, including those from the geoscience domain where data are continuously arriving and are processed. In this paper, we propose an inference-based framework, which provides both workflow and fine-grained data provenance at a minimal cost in terms of time, training, and disk consumption. Our proposed framework is applicable to any given scientific model, and is capable of handling different model dynamics, such as variation in the processing time as well as input data products arrival pattern. Our evaluation of the framework in a real use case with geospatial data shows that the proposed framework is relevant and suitable for scientists in geoscientific domain. [ABSTRACT FROM AUTHOR]

Today's cloud computing becomes more and more popular, and the cloud service also becomes a trend all over the world. Many kinds of cloud services have arisen, and they offer a more convenient and faster way to handle all works. When users start to rely on various services of cloud computing, they need to manage many accounts. It is inconvenient to remember a lot of accounts used for these cloud services. If users can just remember one account for these cloud services, it will become easier and simpler to use all service users needed. Here, we propose a scheme combing single sign-on and smart card to achieve logging into multiple cloud services securely and simply. [ABSTRACT FROM AUTHOR]

Future flash-based solid-state drives (SSDs) must employ increasingly powerful error correction code (ECC) and digital signal processing (DSP) techniques to compensate the negative impact of technology scaling on NAND flash memory device reliability. Currently, all the ECC and DSP functions are implemented in a central SSD controller. However, the use of more powerful ECC and DSP makes such design practice subject to significant speed performance degradation and complicated controller implementation. An EZ-NAND (Error Zero NAND) flash memory design strategy is emerging in the industry, which moves all the ECC and DSP functions to each memory chip. Although EZ-NAND flash can simplify controller design and achieve high system speed performance, its high silicon cost may not be affordable for large-capacity SSDs in computing systems. We propose a quasi-EZ-NAND design strategy that hierarchically distributes ECC and DSP functions on both NAND flash memory chips and the central SSD controller. Compared with EZ-NAND design concept, it can maintain almost the same speed performance while reducing silicon cost overhead. Assuming the use of low-density parity-check (LDPC) code and postcompensation DSP technique, trace-based simulations show that SSDs using quasi-EZ-NAND flash can realize almost the same speed as SSDs using EZ-NAND flash, and both can reduce the average SSD response time by over 90 percent compared with conventional design practice. Silicon design at 65 nm node shows that quasi-EZ-NAND can reduce the silicon cost overhead by up to 44 percent compared with EZ-NAND. [ABSTRACT FROM AUTHOR]

The effect of adjacent bit-line (BL) cell interference on BL current fluctuation (\Delta IBL = \high\ IBL - \low\ IBL) due to random telegraph noise (RTN) in floating-gate nand Flash cell strings is characterized. It was found that the electron current density (Je) of a read cell can be appreciably different depending on the position in the channel width direction because of the interference from adjacent BL cells. The interference can be controlled by the state (program or erase) of the adjacent cells. We verified that \Delta IBL due to RTN increases as a high-Je position is controlled to be close to a trap position in 32-nm nand Flash memory strings. Finally, it was also shown that the adjacent cell interference affects not only \Delta IBL but also the ratio of capture and emission time constants [\ln(\tauc/\taue)]. [ABSTRACT FROM AUTHOR]

Random phase encoding is a unique technique for volume hologram which can be applied to various applications such as holographic multiplexing storage, image encryption, and optical sensing. In this review article, we first review and discuss diffraction selectivity of random phase encoding in volume holograms, which is the most important parameter related to multiplexing capacity of volume holographic storage. We then review an image encryption system based on random phase encoding. The alignment of phase key for decryption of the encoded image stored in holographic memory is analyzed and discussed. In the latter part of the review, an all-optical sensing system implemented by random phase encoding and holographic interconnection is presented [ABSTRACT FROM AUTHOR]

A method of achieving a required level of functional reliability of the storage and transmission devices used with information obtained from computerized measurement instrumentation systems is proposed through an increase in the detectivity of double errors. [ABSTRACT FROM AUTHOR]

Abstract: Use of flash memory as a storage medium is becoming popular in diverse computing environments. However, because of differences in interface, flash memory requires a hard-disk-emulation layer, called FTL (flash translation layer). Although the FTL enables flash memory storages to replace conventional hard disks, it induces significant computational and space overhead. Despite the low power consumption of flash memory, this overhead leads to significant power consumption in an overall storage system. In this paper, we analyze the characteristics of flash-based storage devices from the viewpoint of power consumption and energy efficiency by using various methodologies. First, we utilize simulation to investigate the interior operation of flash-based storage of flash-based storages. Subsequently, we measure the performance and energy efficiency of commodity flash-based SSDs by using microbenchmarks to identify the block-device level characteristics and macrobenchmarks to reveal their filesystem level characteristics. [Copyright &y& Elsevier]

Nonvolatile memories such as Flash memory, phase change memory (PCM), and magnetic random access memory (MRAM) have many desirable characteristics for embedded systems to employ them as main memory. However, there are two common challenges we need to answer before we can apply nonvolatile memory as main memory practically. First, nonvolatile memory has limited write/erase cycles compared to DRAM. Second, a write operation is slower than a read operation on nonvolatile memory. These two challenges can be answered by reducing the number of write activities on nonvolatile main memory. In this paper, we proposed two optimization techniques, write-aware scheduling and recomputation, to minimize write activities on nonvolatile memory. With the proposed techniques, we can both speed up the completion time of programs and extend nonvolatile memory's lifetime. The experimental results show that the proposed techniques can reduce the number of write activities on nonvolatile memory by 55.71% on average. Thus, the lifetime of nonvolatile memory is extended to 2.5 times as long as before on average. The completion time of programs can be reduced by 56.67% on systems with NOR Flash memory and by 47.63% on systems with NAND Flash memory on average. [ABSTRACT FROM AUTHOR]

The real-time control data delivery system of the Critical Infrastructure (i.e. SCADA-Supervisory Control and Data Acquisition system) is important because appropriate decisions cannot be made without having data delivered in a timely manner. Because these applications use multiple heterogeneous resources such as CPU, network bandwidth and storage, they call for an integrated and coordinated real-time scheduling across multiple resources to meet end-to-end deadlines. We present a design and implementation of iDSRT-an integrated dynamic soft real-time system to provide fine-grained end-to-end delay guarantees over WLAN. iDSRT takes the deadline partitioning approach: end-to-end deadlines are partitioned into multiple sub-deadlines for CPU scheduling and network scheduling. It integrates three important schedulers: task scheduler, packet scheduler and node scheduler to achieve global coordination. We validate iDSRT in Linux and evaluate it in an experimental SCADA test-bed. The results are promising and show that iDSRT can successfully achieve soft real-time guarantees in SCADA system with very low packet loss rate compared to available commodity best-effort systems. [ABSTRACT FROM AUTHOR]

Sparse matrix—vector multiply is an important operation in a wide range of problems. One of the key factors determining the performance of this operation is sustained memory bandwidth. In the IBM POWER architecture, there is a hardware component called a prefetch data stream that can significantly increase sustained memory bandwidth. We have developed a new family of storage formats for sparse matrices that exploits this capability. Test results show that our new streamed storage formats can significantly improve the performance of sparse matrix and vector multiply on IBM POWER processors, compared to traditional compressed sparse row and block compressed sparse row formats. The new formats also provide a benefit on x86 processors. [ABSTRACT FROM AUTHOR]

This paper describes the application of evolutionary search to the problem of flash memory wear-out. Flash memory differs from standard RAM in that it can wear out due to the manner in which it is programmed. The operating parameters, such as voltage levels, of flash memory are notoriously difficult to determine, as the optimal values vary from batch to batch. The current method in use is an expensive and time-consuming manual process of destructive testing. Understandably, this process is normally undertaken only at design time and testing on individual batches is normally not feasible. The results are sub-optimum solutions which do not minimise wear-out over the lifetime of the device. This is an enormously important issue in manufacturing, as most Flash Memory devices requiring reliability (e.g. solid state device disk drives) often have 100% or more redundancy to compensate for the wear-out rates. We establish the viability of a hardware platform that utilises an Evolutionary Algorithm to perform destructive experimentation on hard silicon in order to discover optimal or, at least favourable, operating parameter settings automatically in a manufacturing environment. Here, we describe this hardware and reveal results demonstrating an average life extension of between 250 and 350% over the factory set conditions with a maximum life extension exhibited of 700% all for cells within the same device over the factory settings. Furthermore, since the process is automated, it is possible to leverage the spread between process batches to further enhance device specifications, facilitating the near no-cost life extension of a split-gate flash memory device. [ABSTRACT FROM AUTHOR]

Over the past three decades, the suffix tree has served as a fundamental data structure in string processing. However, its widespread applicability has been hindered due to the fact that suffix tree construction does not scale well with the size of the input string. With advances in data collection and storage technologies, large strings have become ubiquitous, especially across emerging applications involving text, time series, and biological sequence data. To benefit from these advances, it is imperative that we have a scalable suffix tree construction algorithm. The past few years have seen the emergence of several disk-based suffix tree construction algorithms. However, construction times continue to be daunting-for example, indexing the entire human genome still takes over 30 hours on a system with 2 gigabytes of physical memory. In this article, we will empirically demonstrate and argue that all existing suffix tree construction algorithms have a severe limitation-to glean reasonable disk I/O efficiency, the input string being indexed must fit in main memory. This limitation is attributed to the poor locality exhibited by existing suffix tree construction algorithms and inhibits both sequential and parallel scalability. To deal with this limitation, we will show that through careful algorithm design, one of the simplest suffix tree construction algorithms can be rearchitected to build a suffix tree in a tiled manner, allowing the execution to operate within a fixed main memory budget when indexing strings of any size. We will also present a parallel extension of our algorithm that is designed for massively parallel systems like the IBM Blue Gene. An experimental evaluation will show that the proposed approach affords an improvement of several orders of magnitude in serial performance when indexing large strings. Furthermore, the proposed parallel extension is shown to be scalable-it is now possible to index the entire human genome on a 1024 processor IBM Blue Gene system in under 15 minutes. [ABSTRACT FROM AUTHOR]

Distributed storage systems have become popular for handling the enormous amount of data in network-centric systems. A distributed storage system provides client processes with the abstraction of a shared variable that satisfies some consistency and reliability properties. Typically, the properties are ensured through a replication-based implementation. This paper presents an algorithm for a replicated read/write register that can tolerate f Byzantine-faulty servers when there are at least a total of 3f+1 replica servers. The targeted consistency condition is weaker than the more frequently supported condition of atomicity, but it is still strong enough to be useful in some important applications. By weakening the consistency condition, the algorithm can support multiple writers more efficiently and more simply than the known multi-writer algorithms for atomic consistency. [ABSTRACT FROM AUTHOR]

We analyze a variant of the well-known Miller-Rabin test, that may be useful in preventing side-channel attacks to the random prime generation on smart cards: In the Miller-Rabin primality test for a positive integer n, one computes repeatedly the expression aωω (mod n) for random bases a ∈ ℕℕ and exponents ωω such that ωω divides n - 1 and ( n - 1)/ ωω is a power of 2. In each round one chooses, at random, a different base a, and uses binary exponentiation to compute aωω (mod n). 'Listening' to many rounds, it seems at least plausible that an outside spy could retrieve the integer n - 1. In the variant we consider, one chooses in each round two positive random integers a and ρρ and applies the test with base a and exponents ωωρρ, ωω as above. This increases the safety against side-channel attacks. However at the same time, it decreases the performance of the Miller-Rabin test. In this article we use elementary means to analyze this variant. We will not be able to obtain results as strong as those by Damgård, Landrock and Pomerance on prime generation using the original Miller-Rabin test. However by imposing restrictions on the random parameter ρρ, we obtain satisfactory estimates on the variant described here which justify practical implementation. [ABSTRACT FROM AUTHOR]

We give a dynamic data structure that can maintain an ε-coreset of n points, with respect to the extent measure, in O(log n) time per update for any constant ε>0 and any constant dimension. The previous method by Agarwal, Har-Peled, and Varadarajan requires polylogarithmic update time. For points with integer coordinates bounded by U, we alternatively get O(log log U) time. Numerous applications follow, for example, on dynamically approximating the width, smallest enclosing cylinder, minimum bounding box, or minimum-width annulus. We can also use the same approach to maintain approximate k-centers in time O(log n) (or O(log log U) if the spread is bounded by U) for any constant k and any constant dimension. For the smallest enclosing cylinder problem, we also show that a constant-factor approximation can be maintained in O(1) randomized amortized time on the word RAM. [ABSTRACT FROM AUTHOR]

We show that the vertices of any plane graph in which every face is incident to at least g vertices can be colored by ⌊(3 g−5)/4 ⌋ colors so that every color appears in every face. This is nearly tight, as there are plane graphs where all faces are incident to at least g vertices and that admit no vertex coloring of this type with more than ⌊(3 g+1)/4 ⌋ colors. We further show that the problem of determining whether a plane graph admits a vertex coloring by k colors in which all colors appear in every face is in ℘ for k=2 and is $\mathcal{NP}$ -complete for k=3,4. We refine this result for polychromatic 3-colorings restricted to 2-connected graphs which have face sizes from a prescribed (possibly infinite) set of integers. Thereby we find an almost complete characterization of these sets of integers (face sizes) for which the corresponding decision problem is in ℘, and for the others it is $\mathcal{NP}$ -complete. [ABSTRACT FROM AUTHOR]

Several types of quantum memory protocols have been presented over the last ten years, including photon echoes, off-resonant Raman scattering, ultraslow light-based quantum mapping processes and resonant Raman optical echoes. These quantum optical memory protocols are limited by a storage time on a scale as short as milliseconds, determined by the spin phase decay time of the storage medium. For applications of long-distance quantum communications, a quantum repeater composed of quantum entanglement swapping and quantum memory must be used. Achieving longer storage times in quantum memory therefore brings a definite advantage to applications of quantum repeaters for long-distance quantum communications. Here, we propose a quantum optical data storage protocol to extend the storage time by several orders of magnitude beyond the conventional limitation of the order of milliseconds. The present ultralong quantum optical storage technique is achieved by introducing an optical locking method to the resonant Raman optical echo protocol. [ABSTRACT FROM AUTHOR]

The use of NAND flash memory for building permanent storage has been increasing in many embedded systems due to idiosyncrasies such as non-volatility and low energy consumption. The persistent requirements for high storage capacity have given rise to the increase of bit density per cell as in multi-level cells but this has come at the expense of performance and has resulted in degradation of durability. in this paper, we introduce a complementary approach to boost the performance and durability of MLC-based storage systems by employing a non-volatile buffer that temporarily holds the data heading to MLCs. We also propose algorithms to efficiently eliminate unnecessary write and erase operations in MLCs by performing a pre-merge in the buffer. Our experiments show that the proposed approach can decrease average response time by up to 4 times and increase durability by 4 times by adding only a small hardware cost. [ABSTRACT FROM AUTHOR]

In the IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, vol. 55, no. 6, Juang et al. proposed a password-authenticated key agreement scheme using smart cards. Although the scheme of Juang et al. has many benefits, we find that it suffers from three weaknesses: 1) inability of the password-changing operation; 2) the session-key problem; and 3) inefficiency of the double secret keys. Therefore, we propose an improved scheme to overcome the weaknesses and maintain the benefits of the original scheme. In addition, our improved scheme reduces the storage and computation costs on the smart card compared with the scheme of Juang et a!. We believe that our improved scheme is more suitable for real-life applications than that of Juang et al. [ABSTRACT FROM AUTHOR]

The article provides information on the development of dielectric, metallization and planarization technologies to meet the needs of memory manufacturers as they transition to copper interconnects. The author states that the PVD barrier technology has been developed to allow PVD extendibility to the 3x nm technology node. Moreover, deposition of the dielectric barrier is another key to copper interconnect reliability.

A double-stacked nanocrystal (DSNC) flash memory is presented for improvement of both program/erase (P/E) speed and data retention time. Four combinations of nickel (Ni) and gold (Au) (Ni/Ni, Au/Au, Ni/Au, and Au/Ni) are used as charge storage DSNC materials and are compared from the perspective of memory performance. Through experimental results for PIE efficiency and retention time, the optimized energy band lineup for faster PIE and longer charge retention is presented. A combination of a deep potential well at the top and a shallow potential well at the bottom exhibits optimized performance in PIE, and this combination also shows the longest data retention characteristics. [ABSTRACT FROM AUTHOR]

Since the existing NAND flash memory file systems manage file data in page units, the memory usage increases greatly as the number and size of files increase, and the area to scan at the mounting time increases linearly as well. To resolve these problems, this paper suggests data management in segment units for more efficient processing of multimedia files to reduce memory usage and to improve reading and writing performance. In addition, it suggests a new index structure and garbage collection method for multimedia files to reduce the mounting time and to improve the wear-leveling effectiveness. This approach shows better performance for multimedia files than existing file systems in terms of reading, writing, memory usage, mounting time, and garbage collection. [ABSTRACT FROM AUTHOR]

In this article we present a system for sharing a Conditional Access Module among different visualization devices. Current pay-TV systems require having conditional access modules and smart cards replicated at every visualization device willing to access Pay-TV contents. In this article, we show how a home gateway, capable of securely distribute decryption keys to home visualization device, an inexpensive descrambler, and a home network, enable a flexible solution to access Pay-TV. [ABSTRACT FROM AUTHOR]

Counting items in a distributed system, and estimating the cardinality of multisets in particular, is important for a large variety of applications and a fundamental building block for emerging Internet-scale information systems. Examples of such applications range from optimizing query access plans in peer-to-peer data sharing, to computing the significance (rank/score) of data items in distributed information retrieval. The general formal problem addressed in this article is computing the network-wide distinct number of items with some property (e.g., distinct files with file name containing "spiderman") where each node in the network holds an arbitrary subset, possibly overlapping the subsets of other nodes. The key requirements that a viable approach must satisfy are: (1) scalability towards very large network size, (2) efficiency regarding messaging overhead, (3) load balance of storage and access, (4) accuracy of the cardinality estimation, and (5) simplicity and easy integration in applications. This article contributes the DHS (Distributed Hash Sketches) method for this problem setting: a distributed, scalable, efficient, and accurate multiset cardinality estimator. DHSis based on hash sketches for probabilistic counting, but distributes the bits of each counter across network nodes in a judicious manner based on principles of Distributed Hash Tables, paying careful attention to fast access and aggregation as well as update costs. The article discusses various design choices, exhibiting tunable trade-offs between estimation accuracy, hop-count efficiency, and load distribution fairness. We further contribute a full-fledged, publicly available, open-source implementation of all our methods, and a comprehensive experimental evaluation for various settings. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to determine the nutritional value of adult commercial cuttlefish, to develop a Quality Index Method (QIM) scheme, and to evaluate the application of some biochemical methods commonly used for freshness assessment of fish under ice storage. Additionally, shelf-life was to be determined based on both QIM and suitable biochemical methods. The nutritional value of the cuttlefish mantle in the first 24h and after 13 days was determined. Captured cuttlefish was composed (g/100g) by 16.60±0.10g protein, 0.09±0.01g fat, 79.55±0.14g moisture and 1.39±0.03g of ash. After 13 days of ice storage, cuttlefish was composed (g/100g) of 11.90±0.28g protein, 0.17±0.09g fat, 87.04±0.13g moisture and 0.52±0.01g of ash. Differences (p <0.001) were found in protein, ash and moisture but not in fat (p >0.05). These results seem to indicate that there is impregnation of the iced water into the mantle tissue promoting protein leaching with the melting ice. TVB-N and TMA-N displayed a similar increasing tendency, peaking beyond EEC regulations proposed maximum between the 9th and 10th days. The developed QIM scheme for cuttlefish was composed of 29 demerit points, divided into 4 attributes and 13 parameters. The calculated quality index (QI) evolved linearly with storage time in ice (QI=2.68×days in ice−0.61, R 2 =0.9866). Storage time could be estimated with an accuracy of±1 day, if five cuttlefish from each sample were included in the QIM assessment. The shelf-life was determined as 8±1 days by both type of methods (QIM and biochemical). However, the suitability of some biochemical methods to assess freshness need to be more thoroughly researched. [Copyright &y& Elsevier]

Abstract: Hydrogen-bonded dimers of tetra-urea calix[4]arenes are able to include ferrocenium ions as a guest. Heterodimeric capsules are exclusively formed in 1:1 mixtures of tetra-arylurea calix[4]arene 1 with tetra-tosylurea calix[4]arene 2. Sulfide groups attached via spacers on the urea rim of 1 allow their binding to metal surfaces rendering simultaneously their dissociation more difficult. Thus, the electrochemical response of encapsulated ferrocenium could be studied in a self-assembled monolayer (SAM) in addition to the solution electrochemistry with cyclic voltammetry. The stability of the electrochemically active monolayers was tested after a heat treatment (225°C for 30min in N2 atmosphere) and multiple cycling (up to 1200 cycles), which could be required for a possible application as molecular based information storage. [Copyright &y& Elsevier]

Abstract: This paper is motivated by the open question whether the union of two disjoint NP-complete sets always is NP-complete. We discover that such unions retain much of the complexity of their single components. More precisely, they are complete with respect to more general reducibilities. Moreover, we approach the main question in a more general way: We analyze the scope of the complexity of unions of m-equivalent disjoint sets. Under the hypothesis that , we construct degrees in NP where our main question has a positive answer, i.e., these degrees are closed under unions of disjoint sets. [Copyright &y& Elsevier]

Abstract: One of the most commonly used two-factor user authentication mechanisms nowadays is based on smart-card and password. A scheme of this type is called a smart-card-based password authentication scheme. The core feature of such a scheme is to enforce two-factor authentication in the sense that the client must have the smart-card and know the password in order to gain access to the server. In this paper, we scrutinize the security requirements of this kind of schemes, and propose a new scheme and a generic construction framework for smart-card-based password authentication. We show that a secure password based key exchange protocol can be efficiently transformed to a smart-card-based password authentication scheme provided that there exist pseudorandom functions and target collision resistant hash functions. Our construction appears to be the first one with provable security. In addition, we show that two recently proposed schemes of this kind are insecure. [Copyright &y& Elsevier]

Thermal energy storage by latent heat allows storing high amounts of energy working in narrow margins of temperature. The use of phase change material (PCM) for the latent heat storage has been studied in different applications and it has been commercialized in containers to transport blood, products sensible to temperature, to decrease their energy demand. The use of PCM in cooling and refrigeration has been attracting a lot of interest lately, but for all applications, the properties of these materials need to be known with sufficient accuracy. Regarding heat storage, it is necessary to know the enthalpy as a function of temperature. The most widely used calorimeter is the heat-flux differential scanning calorimetry (hf-DSC). The objective of this study is to investigate different methods for hf-DSC analysis, namely the dynamic method and the step method, and to test their accuracy in the determination of enthalpy–temperature relationship of PCM. For the dynamic method, a strong influence of heating/cooling rate was observed. For the step method, the resulting enthalpy–temperature relationship is independent of heating/cooling rate. Commercial PCM RT27 was chosen as sample material to avoid subcooling and kinetic effects in the test measurements. The approach introduced in this study can be used to carry out similar investigations for other classes of PCM and/or other DSC instruments. Copyright © 2008 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the dynamic behaviour of free layer damping beams with thick viscoelastic layer is analysed. A homogenised model for the flexural stiffness is formulated employing Reddy and Bickford’s quadratic shear in each layer, in contrast to the classical model of Oberst and Frankenfeld for thin beams, which does not take into account shear deformations. The results provided by these two models in free and forced vibration are compared by means of finite element procedures with those of a 2D model, which considers extensional and shear stress, and longitudinal, transverse and rotational inertias. The viscoelastic material is characterised by a fractional derivative model, which takes into consideration the variation of the complex modulus with frequency. To avoid the frequency dependence of the stiffness matrices, the extraction of the eigenvalues and eigenvectors is completed by a new iterative method developed by the authors. The frequency response to a harmonic force is deduced by the superposition of modal contribution functions. From these numerical applications it can be concluded that the model for thick beams provides sufficient accuracy for practical applications, able to reproduce the mechanical behaviour of free layer damping beams with thick viscoelastic layer, reducing the storage needs and computational time with respect to a 2D model. [Copyright &y& Elsevier]

Abstract: Optical switching and structural transformation of GeTe–Sb2Te3 pseudobinary alloys, Ge2Sb2Te5, Ge1Sb2Te4, and Ge1Sb4Te7, were studied for data storage application. As-deposited Ge2Sb2Te5, Ge1Sb2Te4, and Ge1Sb4Te7 thin films were amorphous and they crystallized to FCC and HCP upon heat treatment. Crystallization was accelerated by increasing the proportion of Sb2Te3 rather than GeTe in Ge–Sb–Te compounds; this was observed by reflectivity changes under nanosecond laser irradiation in static tester. The different crystallization kinetics according to composition might be affected by the structural incompatibility of GeTe under the ‘Umbrella Flip’ theory. [Copyright &y& Elsevier]

High performance, highly reliable, and energy-efficient storage systems are essential for mobile data-intensive applications such as remote surgery and mobile data center. Compared with conventional stationary storage systems, mobile disk-array-based storage systems are more prone to disk failures due to their severe application environments. Further, they have a very limited power supply. Therefore, data reconstruction algorithms which are executed in the presence of disk failure for mobile storage systems must be performance-driven, reliability-aware, and energy-efficient. Unfortunately, existing reconstruction schemes cannot fulfill these three goals simultaneously because they largely overlook the fact that mobile disks have much higher failure rates than stationary disks. Besides, they normally ignore energy saving. In this paper, we develop a novel reconstruction strategy, called multilevel caching-based reconstruction optimization (MICRO), which can be applied to RAID-structured mobile storage systems to noticeably shorten reconstruction times and user response times while saving energy. MICRO collaboratively utilizes storage cache and disk array controller cache to diminish the number of physical disk accesses caused by reconstruction. Experimental results demonstrate that, compared with two representative algorithms, DOR and PRO, MICRO reduces reconstruction times on average by 20.22 percent and 9.34 percent, while saving energy by no less than 30.4 percent and 13 percent, respectively. [ABSTRACT FROM AUTHOR]

Multimedia applications usually have throughput constraints. An implementation must meet these constraints while it minimizes resource usage and energy consumption. The compute intensive kernels of these applications are often specified as Cyclo-Static or Synchronous Dataflow Graphs. Communication between nodes in these graphs requires storage space, which influences throughput. We present an exact technique to chart the Pareto space of throughput and storage trade-offs, which can be used to determine the minimal buffer space needed to execute a graph under a given throughput constraint. The feasibility of the exact technique is demonstrated with experiments on a set of realistic DSP and multimedia applications. To increase the scalability of the approach, a fast approximation technique is developed that guarantees both throughput and a tight bound on the maximal overestimation of buffer requirements. The approximation technique allows us to trade off worst-case overestimation versus runtime. [ABSTRACT FROM AUTHOR]

The article presents a discussion on the potentiality of smart cards to provide strong payments authorization in response to the problems of payments fraud and theft identity in the U.S. It provides a review of the costs of payments fraud and describes how payments fraud is related to identity theft. It explains how smart cards work and how they can improve payment authorization and provides further description of the weaknesses that can remain even with the use of smarts cards. Moreover, it discusses the incentive for adopting payments smart cards and for upgrading payments security standards and examines the market processes that determine the security standards used in payment smart cards.

In this paper, we propose a novel high-κ Y2O3 poly-Si-oxide-nitride-oxide-silicon (SONOS)-type flash memory. The structural and morphological features of Y2O3 films were studied using atomic force microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. These high-κ Y2O3 SONOS-type memories exhibited large threshold voltage shifting (memory window, of 1.9-4.33 V), almost negligible read and gate disturb (threshold voltage shift of ∼2-mV operation at VG = 3 V and VD = 4 V and ∼4-mV operation at VG = 8 V, respectively), excellent data retention (charge loss of ∼4% measured time up to 104 s and at room temperature, expected ∼ 22% charge loss for ten years at 125 °C), and superior endurance characteristics (program/erase cycles up to 105) because of the higher probability for trapping charge carriers. These Y2O3 films appear to be a very promising charge trapping layer for high-density two-bit nonvolatile flash memory applications. [ABSTRACT FROM AUTHOR]