Lattice Boltzmann method study of Rayleigh instability of a charged droplet

Rayleigh instability of a charged droplet is well known. Although the instability condition was revealed by Lord Rayleigh, how the deformation develops after the unstable state still remains a question because of its dynamic nature. Therefore, a numerical simulation method will help to study the dynamics of the deformation of a charged droplet. In this paper we reported an interesting extension of the multi-phase lattice Boltzmann method to involve the electrostatic repulsive force working on the surface of an individual liquid droplet by means of momentum modification to simulate the Rayleigh instability. The method successfully simulates the Rayleigh instability, in which a droplet is stretched into an ellipsoidal shape when the electrostatic potential exceeds the Rayleigh's threshold, whilst a droplet with less potential than the threshold deforms back to a spherical shape as the static form.     

Various methods for the mapping of science

The dynamic mapping of science using the data in theScience Citation Index was put on the research agenda of science studies byDe Solla Price in the mid 1960s. Recently, proponents of ‘co-citation cluster analysis’ have claimed that in principle their methodology makes such mapping possible. The study examines this claim, both methodologically and theoretically, in relation to other means of mapping science. A detailed study of a co-citation map, its core documents' citation patterns and the related journal structures, is presented. At these three levels of possible study of aggregates of citations, an analysis is pursued for the years 1978 to 1984. The many different statistical methods which are in use for the analysis of the respective datamatrices—such as cluster analysis, factor analysis and multidimensional scalling—are assessed with a view to their potential to contribute to a better undérstanding of the dynamics at the different levels in relation to each other. This will lead to some recommendations about methods to use and to avoid when we aim at a comprehensive mapping of science. Although the study is pursued at a formal and analytical level, in the conclusions an attempt is made to reflect on the results in terms of further substantial questions for the study of the dynamics of science.     

面向多用户环境的MapReduce集群调度算法研究

针对MapReduce集群现有调度策略在多用户环境下无法根据用户的实际资源需求实现动态资源分配的问题,提出了一种基于历史执行信息(HEI)的MapReduce集群调度算法——HEI Scheduler。该算法通过建立集群作业执行信息的收集和分析机制,得到各用户组资源需求随时间变化的规律,并以作业实际占用slot的时间作为作业占用资源量的衡量标准,进而动态地确定资源池的最小共享资源以及集群剩余资源分配的权值。实验结果表明,执行信息分析机制能够更准确地表征作业对资源的需求,采用集群调度算法HEI Scheduler能够有效地缩短作业的整体执行时间。     

Chaotic dynamics and reversal statistics of the forced spherical pendulum: comparing the Miles equations with experiment

The forced spherical pendulum is of intrinsic interest to dynamicists as well as to geophysicists as a simple mechanical analogue of the polarity reversals of the Earth's magnetic field. The system displays chaotic dynamics involving irregular reversals of its direction of motion, both in terms of its angular momentum and of its direction of precession. Here, we analyse the difference between angular-momentum and precession reversals and compare the results of experimental work that has been performed on chaotic reversals in a laboratory pendulum with numerical simulations of the Miles equations that represent the pendulum dynamics; we find good agreement.     

Minimising idle times in cluster tools in the semiconductor industry

This paper is dedicated to the problem of sequencing handler's moves in cluster tools in the semiconductor industry. A suboptimal sequence of the handler's moves usually leads to long idle times in the cluster tool's chambers and hence longer makespan and lower throughput. Therefore, an effective algorithm that minimises idle times in the cluster tool's chambers is required. An algorithm called MinBIT (minimising bottleneck idle time) is presented as a new method for sequencing the handler's moves. The MinBIT algorithm gives priority to the bottleneck stage, and thus leads to a reduction in unnecessary idle times and hence a shorter makespan. We compared the MinBIT algorithm with other algorithms. Our algorithm achieved best performance in 98% of the cases. In the other 2% of the cases it achieved second or third best performance. The computational results show that the MinBIT algorithm can improve the performance of a cluster tool by up to 10%. A comparison between the MinBIT solutions and the optimal solutions found by using branch and bound, shows that the deviation between them ranged between 0% and 0.22%, which indicates that MinBIT gives optimal or near optimal results.     

Mass and velocity distributions of low energy cluster beams

We have recently generated several low energy cluster beams by using a laser vaporization source and a pulsed He stream. This has been done both for covalent (silicon and carbon) and metallic (gold) materials. In this work we present a simple procedure to carefully measure the speed and speed distribution of the obtained clusters with the help of an orthogonal time of flight mass spectrometer. Results show average speed values in the range 700–1000 m/s with a mild variation by changing the gas backing pressure and the cluster mass inside each cluster train. Detailed speed distributions for each cluster's mass will be given.     

基于数量化理论的家具造型意象设计

目的 研究从消费者角度分析家具形态特征设计的方法。方法 以新中式座椅为对象,数量化理论为基础,通过家具造型的形容词汇和语意差分法来获取消费者对家具的感性意象,再从部件要素、结构、装饰、材质等多方面,综合提取出影响造型设计的关键要素,并借助聚类分析获取代表性新中式家具样本图片,通过多元回归分析构建用户感性意象与产品造型设计要素之间的关联性模型。结论 初始模型显著性P值略大于显著水平0.05,不能非常显著地表达感性意象与造型设计之间的线性关系,为了使数据更具有科学性得到最优模型,需要采取后退的进入方式建立新的模型,最终通过理论分析为家具造型设计提供指导。     

A century of transitions in New York City's measles dynamics

Infectious diseases spreading in a human population occasionally exhibit sudden transitions in their qualitative dynamics. Previous work has successfully predicted such transitions in New York City''s historical measles incidence using the seasonally forced susceptible–infectious–recovered (SIR) model. This work relied on a dataset spanning 45 years (1928–1973), which we have extended to 93 years (1891–1984). We identify additional dynamical transitions in the longer dataset and successfully explain them by analysing attractors and transients of the same mechanistic epidemiological model.     

Surface erosion and modification by energetic ions

Surface erosion and modification by energetic highly charged and cluster ions are important in the development of semiconductor devices, TeV accelerators, fission and fusion reactors, and in the development of extreme ultra-violet lithography devices. Gas cluster ion beam (GCIB) surface treatment can significantly mitigate the high-gradient electric vacuum breakdown of rf-cavities. GCIB can also mitigate Q-slope drop in superconducting Nb-cavities. Various mechanisms of the highly charged ion (HCI) energy transfer into the solid target, such as hollow atom formation, charge screening and neutralization, shock wave generation, and sputtering were analyzed. Surface erosions caused by GCIB, HCI bombardments, and by low energy He⁺ and H⁺ ions typical for fission and fusion devices were studied by using molecular dynamics simulation. A He bubble splashing mechanism of liquid Li containing was developed, and surface erosion was simulated. The mechanism of bubble explosion could significantly contribute to the surface erosion at high ion fluxes and explain the existing experimental results.     

Analyzing topic evolution in bioinformatics: investigation of dynamics of the field with conference data in DBLP

In this paper we analyze topic evolution over time within bioinformatics to uncover the underlying dynamics of that field, focusing on the recent developments in the 2000s. We select 33 bioinformatics related conferences indexed in DBLP from 2000 to 2011. The major reason for choosing DBLP as the data source instead of PubMed is that DBLP retains most bioinformatics related conferences, and to study dynamics of the field, conference papers are more suitable than journal papers. We divide a period of a dozen years into four periods: period 1 (2000–2002), period 2 (2003–2005), period 3 (2006–2008) and period 4 (2009–2011). To conduct topic evolution analysis, we employ three major procedures, and for each procedure, we develop the following novel technique: the Markov Random Field-based topic clustering, automatic cluster labeling, and topic similarity based on Within-Period Cluster Similarity and Between-Period Cluster Similarity. The experimental results show that there are distinct topic transition patterns between different time periods. From period 1 to period 3, new topics seem to have emerged and expanded, whereas from period 3 to period 4, topics are merged and display more rigorous interaction with each other. This trend is confirmed by the collaboration pattern over time.     

SCHUMPETER IN THE CONTEXT OF TWO CANONS OF ECONOMIC THOUGHT

The publication of Schumpeter's "lost" seventh chapter--with the holistic and Faustian title "The economy as a whole", so typical of the German economic tradition--again raises the question of the ''duality'' in Schumpeter's economic thinking: On the one hand Schumpeter's typical ''Germanic'' approach, emphasizing dynamics, technical change and the entrepreneur, on the other hand his admiration for the mechanical economics of Walras. This paper attempts to explain Schumpeter's duality--his "schizophrenia"--by placing his work in the context of two different canons of economic thought, the standard mainstream canon (the ordnende and passivist-materialist tradition in Werner Sombart's terms) and what we have labelled "The Other Canon" (the verstehende and activist-idealist tradition in Sombart's terminology). The paper attempts to show that in the light of the now almost extinct Other Canon of economics, Schumpeter appears far less original than what he does to today's mainstream. It is argued that while the Harvard Economics Department during Schumpeter's tenure there moved away from the Other Canon type economics, Schumpeter found ample support and research activity in this alternative canon of economics at Harvard Business School. The paper explores the possible influences and similarities of thought on Schumpeter from three economists associated with Harvard Business School: Herbert Somerton Foxwell, Edwin Gay and Fritz Redlich.     

A Green's function approach to deriving non‐reflecting boundary conditions in molecular dynamics simulations

Computer simulations of atomic scale processes in solids are often associated with the issue of spurious reflection of elastic waves at the boundaries of a molecular dynamics domain. In this paper, we propose an approach to emulate non‐reflecting boundary conditions in atomistic simulations of crystalline solids. Harmonic response of the outer, non‐simulated, region is accurately represented by a memory function, related to the lattice dynamics Green's function. The outward wave flow is cancelled due to work done by the corresponding response forces. Performance of method, dependent on a series of method parameters, is illustrated on a benchmark problem. Copyright © 2004 John Wiley & Sons, Ltd.     

Simulation studies of a “nanogun” based on carbon nanotubes

Quantum mechanical molecular dynamics simulations show that electrically neutral carbon nanotubes or fullerene balls housed in an outer carbon nanotube can be driven into motion by charging the outer tube uniformly. Positively and negatively charged outer tube are found to have quite different actions on the initially neutral nanotubes or fullerene balls. A positively charged tube can drive out the molecule inside it out at speeds over 1 km/s, just like a “nanogun”, while a negatively charged tube can drive the molecule into oscillation inside it and can absorb inwards a neutral molecule in the vicinity of its open end, like a “nanomanipulator”. The results demonstrate that changing the charge environment in specific ways may open the door to conceptually new nano/molecular electromechanical devices.     

Fostering SME's co-development of innovative projects in biotech clusters: Extending the sets of enablers for the knowledge creation process

We explore the linkage of specific sets of enablers for the knowledge-creation process (KCP) mobilized in innovative projects co-developed by biotech SMEs and the role of industrial clusters in easing the access to enablers. Two French and one Brazilian high-tech SMEs belonging to two biotechnological clusters were investigated. Deductive and inductive approaches were applied in a complementary manner. Findings revealed a larger set of enablers at the company's level than predicted in the literature. We identified two sets of KCP enablers at the cluster's level, classified as open access and restricted access, which are used for different purposes and simultaneously. These dynamics enabled the studied SMEs to improve their co-developed innovative projects in a more effective way. Data also revealed that the enablers that benefit SMEs are more likely provided by the cluster organisations.     

Geography,Race and the Malleability of Man: Karl von Baer and the Problem of Academic Particularism in the Russian Human Sciences

The question of national specificity in science was vigorously debated in 19th century Russia and remains relevant to the geographical and cultural contextualization of scholarship. This article introduces the term academic particularism to denote this phenomenon and addresses it through an examination of the career, ideas and legacy of Karl von Baer in the fields of geography, ethnology and physical anthropology. The article traces significant shifts in Baer's interests and views after his relocation to Russia in 1835 and identifies a cluster of key ideas present in Baer's work in the mid‐19th century that were further developed by subsequent scholars in the late 19th century and came to constitute a distinctive strain in the Russian human sciences.     

Cluster‐Assembled Nanocomposites: Functional Properties by Design

The unique functional properties of nanocomposites meet many of the material requirements sought after in numerous applications of today's high‐tech industry. This, in turn, inspires material scientists to devise new methods that can further expand the palette of available nanocomposites. Precise control over the chemistry, morphology, and microstructure of nanocomposites' constituents promises the eventual ability to design any composite material for any specific requirement. However, today's synthesis methods still lack the ability to simultaneously control all chemical, morphological, and microstructural features of nanocomposites in a one‐step process. Here, an alternative approach to fabricate fully tailorable nanocomposites under well‐defined conditions is described. In particular, this progress report focuses on the combination of cluster ion beam and thin‐film deposition technologies to fabricate cluster‐assembled nanocomposites via codeposition of cluster ions and matrix materials. Emphasis is given to the state‐of‐the‐art cluster deposition system, designed and built by our research group, as well as to its unique abilities. Moreover, case studies on two cluster‐assembled nanocomposite material systems (Fe/Ag_m and Fe/Cr_m) prepared with this method are presented. Finally, an outlook on research directions for cluster‐assembled nanocomposites is discussed.     

A two-tiered model for simulating the ecological and evolutionary dynamics of rapidly evolving viruses, with an application to influenza

Understanding the epidemiological and evolutionary dynamics of rapidly evolving pathogens is one of the most challenging problems facing disease ecologists today. To date, many mathematical and individual-based models have provided key insights into the factors that may regulate these dynamics. However, in many of these models, abstractions have been made to the simulated sequences that limit an effective interface with empirical data. This is especially the case for rapidly evolving viruses in which de novo mutations result in antigenically novel variants. With this focus, we present a simple two-tiered ‘phylodynamic’ model whose purpose is to simulate, along with case data, sequence data that will allow for a more quantitative interface with observed sequence data. The model differs from previous approaches in that it separates the simulation of the epidemiological dynamics (tier 1) from the molecular evolution of the virus''s dominant antigenic protein (tier 2). This separation of phenotypic dynamics from genetic dynamics results in a modular model that is computationally simpler and allows sequences to be simulated with specifications such as sequence length, nucleotide composition and molecular constraints. To illustrate its use, we apply the model to influenza A (H3N2) dynamics in humans, influenza B dynamics in humans and influenza A (H3N8) dynamics in equine hosts. In all three of these illustrative examples, we show that the model can simulate sequences that are quantitatively similar in pattern to those empirically observed. Future work should focus on statistical estimation of model parameters for these examples as well as the possibility of applying this model, or variants thereof, to other host–virus systems.     

Study of cohabitation and interconnection effects on normal and leukaemic stem cells dynamics in acute myeloid leukaemia

On the basis of recent studies, understanding the intimate relationship between normal and leukaemic stem cells is very important in leukaemia treatment. The authors’ aim in this work is to clarify and assess the effect of coexistence and interconnection phenomenon on the healthy and cancerous stem cell dynamics. To this end, they perform the analysis of two time‐delayed stem cell models in acute myeloid leukaemia. The first model is based on decoupled healthy and cancerous stem cell populations (i.e. there is no interaction between cell dynamics) and the second model includes interconnection between both population''s dynamics. By using the positivity of both systems, they build new linear functions that permit to derive global stability conditions for each model. Moreover, knowing that most common types of haematological diseases are characterised by the existence of oscillations, they give conditions for the existence of a limit cycle (oscillations) in a particularly interesting healthy situation based on Poincare–Bendixson theorem. The obtained results are simulated and interpreted to be significant in understanding the effect of interconnection and would lead to an improvement in leukaemia treatment.Inspec keywords: cellular biophysics, cancer, blood, stability, patient treatmentOther keywords: healthy stem cell dynamics, cancerous stem cell dynamics, time‐delayed stem cell models, acute myeloid leukaemia, cancerous stem cell populations, leukaemia treatment, normal stem cells dynamics, leukaemic stem cells dynamics, intimate relationship, interconnection effects, cohabitation effects, decoupled stem cell populations, global stability conditions, haematological diseases, oscillations, limit cycle, Poincare–Bendixson theorem     

USAD: undetectable steganographic approach in DCT domain

In this work, we propose a new adaptive chaotic steganographic method based on the Discrete Cosine Transform (DCT) and a reversible mapping function. The mapping function is used to map the secret bits into their corresponding symbols. This mapping technique has to preserve the same dynamics, properties and distribution of the original DCT coefficients. The novelty of our approach is based on the adaptive selection phase of embedding spots. This selection is established through a blindness condition which is applied over each image of the database. The proposed embedding scheme within the middle DCT coefficients shows lower probability of detection and higher flexibility in extraction. We evaluate the detection of our method using the Ensemble Classifiers and a set of frequency and spatial domain feature extractors such as the Spatial domain Rich Model (SRM) features, Chen et al.'s 486-dimensional both inter- and intra-block Markov-based features and Liu's 216-dimensional adaptive steganography-based features.     

Fold and flexibility: what can proteins' mechanical properties tell us about their folding nucleus?

The determination of a protein''s folding nucleus, i.e. a set of native contacts playing an important role during its folding process, remains an elusive yet essential problem in biochemistry. In this work, we investigate the mechanical properties of 70 protein structures belonging to 14 protein families presenting various folds using coarse-grain Brownian dynamics simulations. The resulting rigidity profiles combined with multiple sequence alignments show that a limited set of rigid residues, which we call the consensus nucleus, occupy conserved positions along the protein sequence. These residues'' side chains form a tight interaction network within the protein''s core, thus making our consensus nuclei potential folding nuclei. A review of experimental and theoretical literature shows that most (above 80%) of these residues were indeed identified as folding nucleus member in earlier studies.