Preparation of monodispersed oil-in-water emulsions through semi-metal microfluidic EDGE systems

EDGE (Edge-based Droplet GEneration) emulsification systems with the ability to produce multiple droplets simultaneously from a single nozzle, were used for the preparation of monodispersed oil-in-water emulsions. The devices (with plateau height of 1 µm) were coated with metals (Cu, CuNi and CuNi/Cu) and had different surface roughness and wettability properties. This influenced the emulsification behavior significantly. The large surface roughness of the CuNi/Cu coated system resulted in stronger non-uniform filling of the plateau as compared to the smoother surfaces of Cu and less rough CuNi, and less droplet formation points in the CuNi/Cu coated system relative to the Cu and CuNi systems. The less hydrophilic CuNi surface, however, provided wider pressure stability than the more hydrophilic Cu and CuNi/Cu surface. A narrower pressure stability (Cu surface) and lower number of droplet formation points (CuNi/Cu surface) resulted in lower overall droplet formation frequency when compared with CuNi system. All metal coated EDGE systems reliably produced monodispersed droplets (with sizes being 6 times the plateau height), similar to the silicon-based EDGE systems having much smoother surfaces. The pressure stability for CuNi coated surfaces was wider, while the droplet formation frequency was comparable to that with the silicon system. This indicated that the use of metal is not a limitation in these systems as initially expected, but may be used for more robust and productive emulsification systems, which lend themselves well for scale-out to practical productivity rates.     

Designing energy efficient communication runtime systems: a view from PGAS models

As the march to the exascale computing gains momentum, energy consumption of supercomputers has emerged to be the critical roadblock. While architectural innovations are imperative in achieving computing of this scale, it is largely dependent on the systems software to leverage the architectural innovations. Parallel applications in many computationally intensive domains have been designed to leverage these supercomputers, with legacy two-sided communication semantics using Message Passing Interface. At the same time, Partitioned Global Address Space Models are being designed which provide global address space abstractions and one-sided communication for exploiting data locality and communication optimizations. PGAS models rely on one-sided communication runtime systems for leveraging high-speed networks to achieve best possible performance. In this paper, we present a design for Power Aware One-Sided Communication Llibrary – PASCoL. The proposed design detects communication slack, leverages Dynamic Voltage and Frequency Scaling (DVFS), and Interrupt driven execution to exploit the detected slack for energy efficiency. We implement our design and evaluate it using synthetic benchmarks for one-sided communication primitives, Put, Get, and Accumulate and uniformly noncontiguous data transfers. Our performance evaluation indicates that we can achieve significant reduction in energy consumption without performance loss on multiple one-sided communication primitives. The achieved results are close to the theoretical peak available with the experimental test bed.     

Complexity of Rational and Irrational Nash Equilibria

We introduce two new natural decision problems, denoted as ? RATIONAL NASH and ? IRRATIONAL NASH, pertinent to the rationality and irrationality, respectively, of Nash equilibria for (finite) strategic games. These problems ask, given a strategic game, whether or not it admits (i) a rational Nash equilibrium where all probabilities are rational numbers, and (ii) an irrational Nash equilibrium where at least one probability is irrational, respectively. We are interested here in the complexities of ? RATIONAL NASH and ? IRRATIONAL NASH. Towards this end, we study two other decision problems, denoted as NASH-EQUIVALENCE and NASH-REDUCTION, pertinent to some mutual properties of the sets of Nash equilibria of two given strategic games with the same number of players. The problem NASH-EQUIVALENCE asks whether or not the two sets of Nash equilibria coincide; we identify a restriction of its complementary problem that witnesses ? RATIONAL NASH. The problem NASH-REDUCTION asks whether or not there is a so called Nash reduction: a suitable map between corresponding strategy sets of players that yields a Nash equilibrium of the former game from a Nash equilibrium of the latter game; we identify a restriction of NASH-REDUCTION that witnesses ? IRRATIONAL NASH. As our main result, we provide two distinct reductions to simultaneously show that (i) NASH-EQUIVALENCE is co- $\mathcal{NP}$ -hard and ? RATIONAL NASH is $\mathcal{NP}$ -hard, and (ii) NASH-REDUCTION and ? IRRATIONAL NASH are both $\mathcal{NP}$ -hard, respectively. The reductions significantly extend techniques previously employed by Conitzer and Sandholm (Proceedings of the 18th Joint Conference on Artificial Intelligence, pp. 765–771, 2003; Games Econ. Behav. 63(2), 621–641, 2008).     

Kinematic design of a redundant parallel mechanism for maskless lithography optical instrument manipulations

A new precision parallel mechanism having actuation redundancy will be introduced in this paper. Physical contribution of the actuation redundancy for the precision parallel mechanism is reviewed. In addition, several kinematic configurations have been analyzed for degrees of freedom verification and actuation redundancy. A new kinematic configuration which is 4-[P P]PS is suggested. The suggested 4-[P P]PS mechanism which has actuation redundancy provides six degrees of freedom to the mobile platform. For position control and path planning of the mobile platform, the inverse and the forward kinematics are solved for closed-form solutions. In order to verify the inverse and the forward kinematics, a numerical simulation result is presented. In addition to the inverse and forward accuracy proof, the numerical analysis provides other information such as independent translation motion, calibrated rotation arm at tilting motion, and symmetric motion at rotating motion.     

A relation extraction method of Chinese named entities based on location and semantic features

Named entity relations are a foundation of semantic networks, ontology and the semantic Web, and are widely used in information retrieval and machine translation, as well as automatic question and answering systems. In named entity relations, relational feature selection and extraction are two key issues. The location features possess excellent computability and operability, while the semantic features have strong intelligibility and reality. Currently, relation extraction of Chinese named entities mainly adopts the Vector Space Model (VSM), a traditional semantic computing or the classification method, and these three methods use either the location features or the semantic features alone, resulting in unsatisfactory extraction. A relation extraction method of Chinese named entities called LaSE is proposed to combine the information gain of the positions of words and semantic computing based on HowNet. LaSE is scalable, semi-supervised and domain independent. Extensive experiments show that LaSE is superior, with an F-score of 0.879, which is at least 0.113 better than existing extraction methods that use either the location features or the semantic features alone.     

Spatio-temporal polygonal clustering with space and time as first-class citizens

Detecting spatio-temporal clusters, i.e. clusters of objects similar to each other occurring together across space and time, has important real-world applications such as climate change, drought analysis, detection of outbreak of epidemics (e.g. bird flu), bioterrorist attacks (e.g. anthrax release), and detection of increased military activity. Research in spatio-temporal clustering has focused on grouping individual objects with similar trajectories, detecting moving clusters, or discovering convoys of objects. However, most of these solutions are based on using a piece-meal approach where snapshot clusters are formed at each time stamp and then the series of snapshot clusters are analyzed to discover moving clusters. This approach has two fundamental limitations. First, it is point-based and is not readily applicable to polygonal datasets. Second, its static analysis approach at each time slice is susceptible to inaccurate tracking of dynamic cluster especially when clusters change over both time and space. In this paper we present a spatio-temporal polygonal clustering algorithm known as the Spatio-Temporal Polygonal Clustering (STPC) algorithm. STPC clusters spatial polygons taking into account their spatial and topological properties, treating time as a first-class citizen, and integrating density-based clustering with moving cluster analysis. Our experiments on the drought analysis application, flu spread analysis and crime cluster detection show the validity and robustness of our algorithm in an important geospatial application.     

Deciding floating-point logic with abstract conflict driven clause learning

We present a bit-precise decision procedure for the theory of floating-point arithmetic. The core of our approach is a non-trivial, lattice-theoretic generalisation of the conflict-driven clause learning algorithm in modern sat solvers to lattice-based abstractions. We use floating-point intervals to reason about the ranges of variables, which allows us to directly handle arithmetic and is more efficient than encoding a formula as a bit-vector as in current floating-point solvers. Interval reasoning alone is incomplete, and we obtain completeness by developing a conflict analysis algorithm that reasons natively about intervals. We have implemented this method in the mathsat5 smt solver and evaluated it on assertion checking problems that bound the values of program variables. Our new technique is faster than a bit-vector encoding approach on 80 % of the benchmarks, and is faster by one order of magnitude or more on 60 % of the benchmarks. The generalisation of cdcl we propose is widely applicable and can be used to derive abstraction-based smt solvers for other theories.     

Evolutionary Algorithms for Quantum Computers

In this article, we formulate and study quantum analogues of randomized search heuristics, which make use of Grover search (in Proceedings of the 28th Annual ACM Symposium on Theory of Computing, pp. 212–219. ACM, New York, 1996) to accelerate the search for improved offsprings. We then specialize the above formulation to two specific search heuristics: Random Local Search and the (1+1) Evolutionary Algorithm. We call the resulting quantum versions of these search heuristics Quantum Local Search and the (1+1) Quantum Evolutionary Algorithm. We conduct a rigorous runtime analysis of these quantum search heuristics in the computation model of quantum algorithms, which, besides classical computation steps, also permits those unique to quantum computing devices. To this end, we study the six elementary pseudo-Boolean optimization problems OneMax, LeadingOnes, Discrepancy, Needle, Jump, and TinyTrap. It turns out that the advantage of the respective quantum search heuristic over its classical counterpart varies with the problem structure and ranges from no speedup at all for the problem Discrepancy to exponential speedup for the problem TinyTrap. We show that these runtime behaviors are closely linked to the probabilities of performing successful mutations in the classical algorithms.     

Exploiting a hypergraph model for finding Golomb rulers

Golomb rulers are special rulers where for any two marks it holds that the distance between them is unique. They find applications in radio frequency selection, radio astronomy, data encryption, communication networks, and bioinformatics. An important subproblem in constructing “compact” Golomb rulers is Golomb Subruler  (GSR), which asks whether it is possible to make a given ruler Golomb by removing at most \(k\) marks. We initiate a study of GSR from a parameterized complexity perspective. In particular, we consider a natural hypergraph characterization of rulers and investigate the construction and structure of the corresponding hypergraphs. We exploit their properties to derive polynomial-time data reduction rules that reduce a given instance of GSR to an equivalent one with \({{\mathrm{O}}}(k^3)\)  marks. Finally, we complement a recent computational complexity study of GSR by providing a simplified reduction that shows NP-hardness even when all integers are bounded by a polynomial in the input length.     

SNEE: a query processor for wireless sensor networks

A wireless sensor network (WSN) can be construed as an intelligent, large-scale device for observing and measuring properties of the physical world. In recent years, the database research community has championed the view that if we construe a WSN as a database (i.e., if a significant aspect of its intelligent behavior is that it can execute declaratively-expressed queries), then one can achieve a significant reduction in the cost of engineering the software that implements a data collection program for the WSN while still achieving, through query optimization, very favorable cost:benefit ratios. This paper describes a query processing framework for WSNs that meets many desiderata associated with the view of WSN as databases. The framework is presented in the form of compiler/optimizer, called SNEE, for a continuous declarative query language over sensed data streams, called SNEEql. SNEEql can be shown to meet the expressiveness requirements of a large class of applications. SNEE can be shown to generate effective and efficient query evaluation plans. More specifically, the paper describes the following contributions: (1) a user-level syntax and physical algebra for SNEEql, an expressive continuous query language over WSNs; (2) example concrete algorithms for physical algebraic operators defined in such a way that the task of deriving memory, time and energy analytical cost-estimation models (CEMs) for them becomes straightforward by reduction to a structural traversal of the pseudocode; (3) CEMs for the concrete algorithms alluded to; (4) an architecture for the optimization of SNEEql queries, called SNEE, building on well-established distributed query processing components where possible, but making enhancements or refinements where necessary to accommodate the WSN context; (5) algorithms that instantiate the components in the SNEE architecture, thereby supporting integrated query planning that includes routing, placement and timing; and (6) an empirical performance evaluation of the resulting framework.     

The PSurface library

We describe PSurface, a C $++$ library that allows to store and access piecewise linear maps between simplicial surfaces in $\mathbb{R }^2$ and $\mathbb{R }^3$ . Piecewise linear maps can be used, e.g., to construct boundary approximations for finite element grids, and grid intersections for domain decomposition methods. In computer graphics the maps allow to build level-of-detail representations as well as texture- and bump maps. The PSurface library can be used as the basis for the implementation of a wide range of algorithms that use piecewise linear maps between triangulated surfaces. A few simple examples are given in this work. We document the data structures and algorithms and show how PSurface is used in the numerical analysis framework Dune and the visualization software Amira.     

Amplifying circuit lower bounds against polynomial time, with applications

We give a self-reduction for the Circuit Evaluation problem (CircEval) and prove the following consequences.

1. Amplifying size–depth lower bounds. If CircEval has Boolean circuits of n ^k size and n ^1?δ depth for some k and δ, then for every ${\epsilon > 0}$ , there is a δ′ > 0 such that CircEval has circuits of ${n^{1 + \epsilon}}$ size and ${n^{1- \delta^{\prime}}}$ depth. Moreover, the resulting circuits require only ${\tilde{O}(n^{\epsilon})}$ bits of non-uniformity to construct. As a consequence, strong enough depth lower bounds for Circuit Evaluation imply a full separation of P and NC (even with a weak size lower bound).
2. Lower bounds for quantified Boolean formulas. Let c, d > 1 and e < 1 satisfy c < (1 ? e + d )/d. Either the problem of recognizing valid quantified Boolean formulas (QBF) is not solvable in TIME[n ^c ], or the Circuit Evaluation problem cannot be solved with circuits of n ^d size and n ^e depth. This implies unconditional polynomial-time uniform circuit lower bounds for solving QBF. We also prove that QBF does not have n ^c -time uniform NC circuits, for all c < 2.

     

Small Space Analogues of Valiant’s Classes and the Limitations of Skew Formulas

In the uniform circuit model of computation, the width of a boolean circuit exactly characterizes the “space” complexity of the computed function. Looking for a similar relationship in Valiant’s algebraic model of computation, we propose width of an arithmetic circuit as a possible measure of space. In the uniform setting, we show that our definition coincides with that of VPSPACE at polynomial width. We introduce the class VL as an algebraic variant of deterministic log-space L; VL is a subclass of VP. Further, to define algebraic variants of non-deterministic space-bounded classes, we introduce the notion of “read-once” certificates for arithmetic circuits. We show that polynomial-size algebraic branching programs (an algebraic analog of NL) can be expressed as read-once exponential sums over polynomials in ${{\sf VL}, {\it i.e.}\quad{\sf VBP} \in \Sigma^R \cdot {\sf VL}}$ . Thus, read-once exponential sums can be viewed as a reasonable way of capturing space-bounded non-determinism. We also show that Σ ^R ·VBP = VBP, i.e. VBPs are stable under read-once exponential sums. Though the best upper bound we have for Σ ^R ·VL itself is VNP, we can obtain better upper bounds for width-bounded multiplicatively disjoint (md-) circuits. Without the width restriction, md- arithmetic circuits are known to capture all of VP. We show that read-once exponential sums over md- constant-width arithmetic circuits are within VP and that read-once exponential sums over md- polylog-width arithmetic circuits are within VQP. We also show that exponential sums of a skew formula cannot represent the determinant polynomial.     

A secure wireless communication system integrating RSA,Diffie–Hellman PKDS,intelligent protection-key chains and a Data Connection Core in a 4G environment

In broadband wireless technology, due to having many salient advantages, such as high data rates, quality of service, scalability, security, mobility, etc., LTE-A currently has been one of the trends of wireless system development. This system provides several sophisticated authentication and encryption techniques to enhance its system security. However, LTE-A still suffers from various attacks, like eavesdropping and replay attacks. Therefore, in this paper, we propose a novel security scheme, called the security system for a 4G environment (Se4GE for short), which as an LTE-A-based system integrates the RSA and Diffie–Hellman algorithms to solve some of LTE-A’s security drawbacks where LTE-A stands for LTE-Advance which is a 4G system. The Se4GE is an end-to-end ciphertext transfer mechanism which dynamically changes encryption keys to enforce the security of data transmission in an LTE-A system. The Se4GE also produces several logically connected random keys, called the intelligent protection-key chain, which invokes two encryption/decryption techniques to provide users with broader demands for security services. The analytical results show that the Se4GE has higher security level than that of an LTE-A system.     

Two-Way Automata Versus Logarithmic Space

We strengthen a previously known connection between the size complexity of two-way finite automata ( ) and the space complexity of Turing machines (tms). Specifically, we prove that

every s-state has a poly(s)-state that agrees with it on all inputs of length ≤s if and only if NL?L/poly, and

every s-state has a poly(s)-state that agrees with it on all inputs of length ≤2 ^s if and only if NLL?LL/polylog.

Here, and are the deterministic and nondeterministic , NL and L/poly are the standard classes of languages recognizable in logarithmic space by nondeterministic tms and by deterministic tms with access to polynomially long advice, and NLL and LL/polylog are the corresponding complexity classes for space O(loglogn) and advice length poly(logn). Our arguments strengthen and extend an old theorem by Berman and Lingas and can be used to obtain variants of the above statements for other modes of computation or other combinations of bounds for the input length, the space usage, and the length of advice.     

Activity of the integrated on-line trypsin microreactor and nanoelectrospray emitter in acetonitrile–water co-solvent mixtures

The on-line trypsin microreactor and nanoelectrospray emitter for peptide mass mapping was demonstrated to be functional under aqueous conditions, but it is well known that electrospray ionization works more efficiently with organic co-solvents. Here, an activity assay was developed to determine the activity of this integrated device with acetonitrile as a co-solvent. Trypsin was immobilized onto fused silica capillaries pulled to fine tips as integrated microreactors coupled as nanoelectrospray ionization emitters. The model substrate N _α-benzoyl-l-arginine ethyl ester (2.5–20 μM) and an internal standard (N _α-Z-l-arginine (Z-Arg)) were dissolved in acetonitrile/water at various ratios and infused through the immobilized trypsin microreactor. The trypsin digestion product N _α-benzoyl-l-arginine (B-Arg) was detected by nanoelectrospray ionization coupled to an ion trap mass spectrometer, and its abundance compared to Z-Arg for quantification. The activity of immobilized trypsin in the microreactor was determined by measuring the ratio of the peak intensities of the hydrolysis product B-Arg to Z-Arg internal standard (three replicates). Kinetic parameters determined from Lineweaver–Burk analysis indicate an enhancement of trypsin activity upon immobilization and the addition of increasing ratios of acetonitrile up to 80 %, where K _m is 0.14 mM and V _max = 1.2 μM/s. Much lower immobilized trypsin activities were noted at 100 % ammonium acetate or 100 % acetonitrile than when the two solvents were mixed. The results clearly indicate that immobilized trypsin retains high biocatalytic activity in 20–80 % acetonitrile and is highly compatible with nanoelectrospray ionization mass spectrometry.     

The clock constraint specification language for building timed causality models

The uml Profile for Modeling and Analysis of Real-Time and Embedded (RTE) systems has recently been adopted by the OMG. Its Time Model extends the informal and simplistic Simple Time package proposed by Unified Modeling Language (UML2) and offers a broad range of capabilities required to model RTE systems including discrete/dense and chronometric/logical time. The Marte specification introduces a Time Structure inspired from several time models of the concurrency theory and proposes a new clock constraint specification language (ccsl) to specify, within the context of the uml, logical and chronometric time constraints. A semantic model in ccsl is attached to a (uml) model to give its timed causality semantics. In that sense, ccsl is comparable to the Ptolemy environment, in which directors give the semantics to models according to predefined models of computation and communication. This paper focuses on one historical model of computation of Ptolemy [Synchronous Data Flow (SDF)] and shows how to build SDF graphs by combining uml models and ccsl.     

Log-Space Algorithms for Paths and Matchings in k-Trees

Reachability and shortest path problems are NL-complete for general graphs. They are known to be in L for graphs of tree-width 2 (Jakoby and Tantau in Proceedings of FSTTCS’07: The 27th Annual Conference on Foundations of Software Technology and Theoretical Computer Science, pp. 216–227, 2007). In this paper, we improve these bounds for k-trees, where k is a constant. In particular, the main results of our paper are log-space algorithms for reachability in directed k-trees, and for computation of shortest and longest paths in directed acyclic k-trees. Besides the path problems mentioned above, we also consider the problem of deciding whether a k-tree has a perfect matching (decision version), and if so, finding a perfect matching (search version), and prove that these two problems are L-complete. These problems are known to be in P and in RNC for general graphs, and in SPL for planar bipartite graphs, as shown in Datta et al. (Theory Comput. Syst. 47:737–757, 2010). Our results settle the complexity of these problems for the class of k-trees. The results are also applicable for bounded tree-width graphs, when a tree-decomposition is given as input. The technique central to our algorithms is a careful implementation of the divide-and-conquer approach in log-space, along with some ideas from Jakoby and Tantau (Proceedings of FSTTCS’07: The 27th Annual Conference on Foundations of Software Technology and Theoretical Computer Science, pp. 216–227, 2007) and Limaye et al. (Theory Comput. Syst. 46(3):499–522, 2010).     

On Rewriting Rules in Mizar

This paper presents some tentative experiments in using a special case of rewriting rules in Mizar (Mizar homepage: http://www.mizar.org/): rewriting a term as its subterm. A similar technique, but based on another Mizar mechanism called functor identification (Korni?owicz 2009) was used by Caminati, in his paper on basic first-order model theory in Mizar (Caminati, J Form Reason 3(1):49–77, 2010, Form Math 19(3):157–169, 2011). However for this purpose he was obligated to introduce some artificial functors. The mechanism presented in the present paper looks promising and fits the Mizar paradigm.     

Verification and validation meet planning and scheduling

A planning and scheduling (P&S) system takes as input a domain model and a goal, and produces a plan of actions to be executed, which will achieve the goal. A P&S system typically also offers plan execution and monitoring engines. Due to the non-deterministic nature of planning problems, it is a challenge to construct correct and reliable P&S systems, including, for example, declarative domain models. Verification and validation (V&V) techniques have been applied to address these issues. Furthermore, V&V systems have been applied to actually perform planning, and conversely, P&S systems have been applied to perform V&V of more traditional software. This article overviews some of the literature on the fruitful interaction between V&V and P&S.