Crystallographic features during martensitic transformation in Ni-Mn-Ga ferromagnetic shape memory alloys

The martensitic transformation crystallography in two Ni ₅₃Mn₂₅Ga₂₂ (at. %) ferromagnetic shape memory alloys (FSMAs) was investigated by means of misorientation calculation and pole figure analysis based on the orientation of the martensitic lamellae obtained from electron backscattered diffraction (EBSD) measurements. In the alloy that was first annealed at 1073K for 4h, and then cooled to 473K at ~4K/min and held for 30min, followed by cooling to room temperature at ~10K/min, there are only two kinds of differently orientated martensitic lamellae with a misorientation angle of ~82° distributed alternatively in each initial austenite grain. There is a compound twinning orientation relationship between the two lamellae. The prevalent orientation relationship between austenite and martensite is Kurdjumov-Sachs (K-S) relationship with (111)_A//(10I)_M, [1-10]_a//[11-1]_m. In the alloy that was annealed at 1173K for 4h followed by furnace cooling, nanoscale twins inside the martensitic lamellae were observed and the orientation relationships both between the nanotwins within one lamella and between the nanotwins in two neighboring lamellae were determined. The results presented in this paper will enrich the crystallographic data of the FSMAs and offer useful information for the development of novel FSMAs with optimal performances.

Structure and phase stability of NiMnGa ferromagnetic shape memory alloys by experimental and ab-initio techniques

This paper summarizes some of our recent results on crystal structure, microstructure, orientation relationship between martensitic variants and crystallographic features of martensitic transformation in Ni-Mn-Ga FSMAs. It was shown that Ni53Mn25Ga22 has a tetragonal I4/mmm martensitic structure at room temperature. The neighboring martensitic variants in Ni53Mn25Ga22 have a compound twinning relationship with the twinning elements K1={112}, K2={11-2}, η1=<11-1>, η2=<111>, P={1-10} and s=0.379. The ratio of the relative amounts of twins within the same initial austenite grain is ~1.70. The main orientation relationship between austenite and martensite is Kurdjumov-Sachs (K-S) relationship. Based on the crystallographic phenomenological theory, the calculated habit plane is {0.690 -0.102 0.716}A (5.95° from {101}A), and the magnitude, direction and shear angle of the macroscopic transformation shear are 0.121, <-0.709 0.105 0.698>A (6.04° from <-101>A) and 6.88°, respectively.

Wikis : transactive memory systems in digital form

Wikis embed information about authors, tags, hyperlinks and other metadata into the information they create. Wiki functions use this metadata to provide pointers which allow users to track down, or be informed of, the information they need. In this paper we provide a firm theoretical conceptualization for this type of activity by showing how this metadata provides a digital foundation for a Transactive Memory System (TMS). TMS is a construct from group psychology which defines directory-based knowledge sharing processes to explain the phenomenon of "group mind". We analyzed the functions and data of two leading Wiki products to understand where and how they support the TMS. We then modeled and extracted data from these products into a network analysis product. The results confirmed that Wikis are a TMS in digital form. Network analysis highlights its characteristics as a "knowledge map", suggesting useful extensions to the internal "TMS" functions of Wikis.

Adaptive autobiographical memory in younger and older adults : the indirect association of integrative and instrumental reminiscence with depressive symptoms

Despite the established effectiveness of reminiscence-based interventions for depression, little research exists into the pathways through which specific reminiscence functions are related to depressive symptoms. Drawing on theory of the mechanisms of change in cognitive-reminiscence therapy, the current study tests the hypothesised indirect associations of adaptive integrative and instrumental reminiscence functions with depressive symptoms and whether these relationships might differ among younger and older adults. Questionnaires were completed by a large community sample of the Australian population. Multiple mediation models were tested in two groups: younger adults (n=730, M age=52.24, SD=9.84) and older adults (n=725, M age= 73.59, SD=6.29). Results were consistent across age groups, indicating that there was direct relationship between these reminiscence functions and depressive symptoms, but that integrative reminiscence is indirectly associated with depressive symptoms through meaning in life, self-esteem, and optimism, and that instrumental reminiscence is indirectly associated with depressive symptoms through primary control and self-efficacy. This study provides support for the relationships between constructs underlying the proposed mechanisms of change in cognitive-reminiscence therapy for the treatment of depression, and suggests these relationships are similar for younger and older adults.

Organizational memory and empowerment

Purpose – The aim of this paper is to test a model of the relationship between organizational memory and empowerment. The model posited that organizational memory would be related to requests to share knowledge, psychological empowerment in the workplace (meaning, competence, self-determination and impact), and organization-based self-esteem. Design/methodology/approach – The model was tested with 134 employees representing six companies using hierarchical regression analysis. Findings – Significant relationships were found between organizational memory and requests to share knowledge, empowerment, and organization-based self-esteem. Findings indicated that a positive stereotype may exist towards older workers and the frequency they are requested to share knowledge, and that a halo-type effect may operate, where knowledge of an organization's history is generalized to other knowledge domains. Research limitations/implications – Causal implications cannot be made as this was correlational research. Some of the research measures while achieving acceptable to good reliability were in an early development stage. The study utilized a convenience sample that may limit how the results can be generalized. Practical implications – The paper indicates that organizations can emphasize positive outcomes for those who are knowledge repositories and mentors. It is also important to consider possible “positive stereotypes” which may be operating when organizational members evaluate older workers as knowledge repositories and mentors. Originality/value – The paper addresses the assumptions in the human resources literature concerning the role of older workers as repositories of organizational memory and suitable mentors. The study introduces the “requests to share knowledge scale”.

Reminiscence-based therapies for depression: should they be used only with older adults?

Reminiscence-based therapies have been reliably evidenced to be an effective intervention for depression. However, to date, their use has been restricted primarily to older adults. This article reviews empirical findings related to the various functions of reminiscence and their correlates with mental health. Reminiscence-based interventions and their effectiveness are then reviewed, with a particular focus on recent evaluations of structured reminiscence-based therapies that utilize preexisting therapeutic frameworks for the treatment for depression. The exclusive use of reminiscence-based therapies with older adult populations is then challenged, and it is argued that these approaches may be useful for reducing depression symptomatology for young and middle-aged adults also. Considerations for the use of reminiscence-based therapies in these populations are discussed, and future directions for research are presented.

Dividing traffic sub-areas based on a parallel K-means algorithm

In order to alleviate the traffic congestion and reduce the complexity of traffic control and management, it is necessary to exploit traffic sub-areas division which should be effective in planing traffic. Some researchers applied the K-Means algorithm to divide traffic sub-areas on the taxi trajectories. However, the traditional K-Means algorithms faced difficulties in processing large-scale Global Position System(GPS) trajectories of taxicabs with the restrictions of memory, I/O, computing performance. This paper proposes a Parallel Traffic Sub-Areas Division(PTSD) method which consists of two stages, on the basis of the Parallel K-Means(PKM) algorithm. During the first stage, we develop a process to cluster traffic sub-areas based on the PKM algorithm. Then, the second stage, we identify boundary of traffic sub-areas on the base of cluster result. According to this method, we divide traffic sub-areas of Beijing on the real-word (GPS) trajectories of taxicabs. The experiment and discussion show that the method is effective in dividing traffic sub-areas.

Effective methods and strategies for massive small files processing based on Hadoop

The Hadoop framework provides a powerful way to handle Big Data. Since Hadoop has inherent defects of high memory overhead and low computing performance in processing massive small files, we implement three methods and propose two strategies for solving small files problem in this paper. First, we implement three methods, i.e., Hadoop Archives (HAR), Sequence Files (SF) and CombineFileInputFormat (CFIF), to compensate the existing defects of Hadoop. Moreover, we propose two strategies for meeting the actual needs of different users. Finally, we evaluate the efficiency of the implemented methods and the validity of the proposed strategies. The experimental results show that our methods and strategies can improve the efficiency of massive small files processing, thereby enhancing the overall performance of Hadoop. © 2014 ISSN 1881-803X.

Tree-based iterated local search for Markov random fields with applications in image analysis

The maximum a posteriori assignment for general structure Markov random fields is computationally intractable. In this paper, we exploit tree-based methods to efficiently address this problem. Our novel method, named Tree-based Iterated Local Search (T-ILS), takes advantage of the tractability of tree-structures embedded within MRFs to derive strong local search in an ILS framework. The method efficiently explores exponentially large neighborhoods using a limited memory without any requirement on the cost functions. We evaluate the T-ILS on a simulated Ising model and two real-world vision problems: stereo matching and image denoising. Experimental results demonstrate that our methods are competitive against state-of-the-art rivals with significant computational gain.

Improved processing speed: online computer-based cognitive training in older adults

In an increasingly aging population, a number of adults are concerned about declines in their cognitive abilities. Online computer-based cognitive training programs have been proposed as an accessible means by which the elderly may improve their cognitive abilities; yet, more research is needed in order to assess the efficacy of these programs. In the current study, a commercially available 21-day online computer-based cognitive training intervention was administered to 34 individuals aged between 53 and 75 years. The intervention consisted of computerized training in reaction time, inspection time, short-term memory for words, executive function, visual spatial acuity, arithmetic, visual spatial memory, visual scanning/discrimination, and n-back working memory. An active solitaire control group was also included. Participants were tested at baseline, posttraining and at three-weeks follow-up using a battery of neuropsychological outcome measures. These consisted of simple reaction time, complex reaction time, digit forwards and backwards, spatial working memory, digit symbol substitution, RAVLT, and trail making. Significant improvement in simple reaction time and choice reaction time task was found in the cognitive training group both posttraining and at three-weeks follow-up. However, no significant improvements on the other cognitive tasks were found. The training program was found to be successful in achieving transfer of trained cognitive abilities in speed of processing to similar untrained tasks. © 2012 Copyright Taylor and Francis Group, LLC.

Development of high performance materials based on smart elastomer nanocomposites

 The present thesis explores the fabrication of technologically relevant nanocomposites out of a few elastomers and conducting fillers like carbon nanotubes, graphene and polyaniline. The developed materials have good applications in sensors, shape memory devices and capacitors. Different characterization methods reveal the influence of filler-elastomer interactions on the various properties of the obtained nanocomposites as well.

Schooling duration rather than chronological age predicts working memory between 6 and 7 years: memory maestros study

OBJECTIVE: Low working memory (WM) is strongly linked with poor academic outcomes. WM capacity increases across childhood but how exposure to school is associated with WM development is not known. We aimed to determine extent to which chronological age and schooling duration are associated with WM at the population level. METHODS: In 2012, children in Grade 1 (the second year of formal schooling in Victoria, Australia) from 44 schools in metropolitan Melbourne were recruited. Assessments occurred over the entire school year, with schools quasi-randomly allocated to one of the 4 school terms. WM (primary outcome) was measured using 2 subtests from the computerized Automated Working Memory Assessment: Backwards Digit Recall (verbal) and Mister X (visuospatial). Linear regression was used to examine relationships of WM with time in school and age. RESULTS: Of the 1765 who provided consent, 1727 children (97.9%) had WM assessed throughout the 2012 school year. WM scores became steadily higher over the course of the year. Thus, scores were .77 and .53 SDs higher in Term 4 than Term 1 for verbal and visuospatial WM, respectively (p values for trend for both scores <.001); conclusions were unchanged when adjusted for age and potential confounders. Conversely, age associations attenuated fully once adjusted for school duration. CONCLUSIONS: Our results demonstrate, for the first time, that the developmental increases in WM are strongly associated with time spent in the classroom, above and beyond chronological age.

Two maximum entropy-based algorithms for running quantile estimation in nonstationary data streams

The need to estimate a particular quantile of a distribution is an important problem that frequently arises in many computer vision and signal processing applications. For example, our work was motivated by the requirements of many semiautomatic surveillance analytics systems that detect abnormalities in close-circuit television footage using statistical models of low-level motion features. In this paper, we specifically address the problem of estimating the running quantile of a data stream when the memory for storing observations is limited. We make the following several major contributions: 1) we highlight the limitations of approaches previously described in the literature that make them unsuitable for nonstationary streams; 2) we describe a novel principle for the utilization of the available storage space; 3) we introduce two novel algorithms that exploit the proposed principle in different ways; and 4) we present a comprehensive evaluation and analysis of the proposed algorithms and the existing methods in the literature on both synthetic data sets and three large real-world streams acquired in the course of operation of an existing commercial surveillance system. Our findings convincingly demonstrate that both of the proposed methods are highly successful and vastly outperform the existing alternatives. We show that the better of the two algorithms (data-aligned histogram) exhibits far superior performance in comparison with the previously described methods, achieving more than 10 times lower estimate errors on real-world data, even when its available working memory is an order of magnitude smaller.

Nanoscale variation in energy dissipation in austenitic shape memory alloys in ultimate loading cycles

Wavy behaviours of hysteresis energy variation in nanoscale bulk of thermomechanical austenitic NiTi shape memory alloy are reported in ultimate nanoindentation loading cycles. One sharp and two spherical tips were used while two loading-unloading rates were applied. For comparison, another austenitic copper-based shape memory alloy, CuAlNi shape memory alloy, and a metal with no phase transition, elastoplastic Cu, were investigated. In shape memory alloys, the hysteresis energy variation ultimately undergoes a linear decrease with internal wavy fluctuations and no stabilisation was observed. The internal energy fluctuation in these alloys was found dissimilar depending on the loading-unloading rate and the indentation tip geometry. In contrast, there was an absence of both overall and internal variations in hysteresis energy for Cu after the second loading cycle. The underlying physics of these variations is discussed and found to be attributed to both the created dislocations and ratcheting thermal-mechanical behaviour of the phase-transformed volume in shape memory alloys.

Understanding the critical distance in sparse distributed memory

Modelos de tomada de decisão necessitam refletir os aspectos da psi- cologia humana. Com este objetivo, este trabalho é baseado na Sparse Distributed Memory (SDM), um modelo psicologicamente e neuro- cientificamente plausível da memória humana, publicado por Pentti Kanerva, em 1988. O modelo de Kanerva possui um ponto crítico: um item de memória aquém deste ponto é rapidamente encontrado, e items além do ponto crítico não o são. Kanerva calculou este ponto para um caso especial com um seleto conjunto de parâmetros (fixos). Neste trabalho estendemos o conhecimento deste ponto crítico, através de simulações computacionais, e analisamos o comportamento desta “Critical Distance” sob diferentes cenários: em diferentes dimensões; em diferentes números de items armazenados na memória; e em diferentes números de armazenamento do item. Também é derivada uma função que, quando minimizada, determina o valor da “Critical Distance” de acordo com o estado da memória. Um objetivo secundário do trabalho é apresentar a SDM de forma simples e intuitiva para que pesquisadores de outras áreas possam imaginar como ela pode ajudá-los a entender e a resolver seus problemas.