bluuebunny/crossref_metadata_2025 huggingface dataset:
A dynamical quasiparticle approach for the QGP bulk and transport properties
Authors: Berrehrah Hamza , Bratkovskaya Elena , Steinert Thorsten , Cassing Wolfgang
Published: May 2016

The properties of quantum chromodynamics (QCD) nowadays are accessible by lattice QCD calculations at vanishing quark chemical potential [Formula: see text], but often lack a transparent physical interpretation. In this review, we report about results from an extended dynamical quasiparticle model (DQPM[Formula: see text]) in which the effective parton propagators have a complex self-energy that depends on the temperature [Formula: see text] of the medium as well as on the chemical potential [Formula: see text] and the parton three-momentum [Formula: see text] with respect to the medium at rest. It is demonstrated that this approach allows for a good description of QCD thermodynamics with respect to the entropy density, pressure, etc. above the critical temperature [Formula: see text] 158 MeV. Furthermore, the quark susceptibility [Formula: see text] and the quark number density [Formula: see text] are found to be reproduced simultaneously at zero and finite quark chemical potential. The shear and bulk viscosities [Formula: see text], and the electric conductivity [Formula: see text] from the DQPM[Formula: see text] also turn out in close agreement with lattice results for [Formula: see text] =0. The DQPM[Formula: see text], furthermore, allows to evaluate the momentum [Formula: see text], [Formula: see text] and [Formula: see text] dependencies of the partonic degrees of freedom also for larger [Formula: see text] which are mandatory for transport studies of heavy-ion collisions in the regime 5[Formula: see text]GeV [Formula: see text] 10[Formula: see text]GeV. We finally calculate the charm quark diffusion coefficient [Formula: see text] – evaluated from the differential cross-sections of partons in the medium for light and heavy quarks by employing the propagators and couplings from the DQPM – and compare it to the available lattice data. It is argued that the complete set of observables allows for a transparent interpretation of the properties of hot QCD.
Two-Dimensional Multi-Release Software Reliability Modeling for Fault Detection and Fault Correction Processes
Authors: Kumar Vijay , Mathur Paridhi , Sahni Ramita , Anand Mohit
Published: May 2016

With the growing competition and the demand of the customers, a software organization needs to regularly provide up-gradations and add features to its existing version of software. For the organization, creating these software upgrades means an increase in the complexity of the software which in turn leads to the increase in the number of faults. Also, the faults left undetected in the previous version need to be addressed in this phase. Many software reliability growth models have been proposed to model the phenomenon of multi-release problems using two stage failure observation and correction processes. The model proposed in this paper partitions the fault removal process into a two-stage process which includes fault detection process and fault removal process considering the joint effect of premeditated release pressure and resource restrictions using a well-known Cobb–Douglas production function for the multi release problem of a software. The faults detected in the operational phase of the previous release or left incomplete are also incorporated in the next release. A generalized framework for the multi-release problem in which fault detection follows an exponential distribution function and fault correction follows Gamma distribution function is proposed and verified on a real data set of four releases of software. The estimated parameters and comparison criteria are also given.
CHIRAL SUPRAMOLECULAR SELF-ASSEMBLY OF 2,2’:6’,2”-TERPYRIDINE-4’-CARBOXYLIC ACID MOLECULES CHEMICALLY ADSORBED ON Cu(111)
Authors: JIANG DANFENG , LU YAN , LING JIE , LENG XINLI , LIU XIAOQING , WANG LI
Published: May 2016

In this paper, large-area chiral supramolecular self-assembly of 2,2’:6’,2”-terpyridine-4’-carboxylic acid (C[Formula: see text]H[Formula: see text]N3O2; Y) molecules on Cu(111) is studied using scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. The basic building blocks of such a self-assembled monolayer are triangular vortex-shaped supramolecular structures containing three twisted Y molecules. Chirality is maintained and transferred from one vortex to the adjacent vortex in successive molecular domains within the same atomic terrace. The twisted Y molecule, bridging two nearest-neighbor Cu atoms, is stabilized by symmetric Cu–O bonds on the surface. The near perpendicularity of these bonds to the surface is the main reason for the formation of “standing-up” Y molecules.
EFFICIENT HEDGING OF PATH–DEPENDENT OPTIONS
Authors: KOLKIEWICZ ADAM W.
Published: May 2016

In this paper, we propose a novel method of hedging path-dependent options in a discrete-time setup. Assuming that prices are given by the Black–Scholes model, we first describe the residual risk when hedging a path-dependent option using only an European option. Then, for a fixed hedging interval, we find the hedging option that minimizes the shortfall risk, which we define as the expectation of the shortfall weighted by some loss function. We illustrate the method using Asian options, but the methodology is applicable to other path-dependent contacts.
Looking Forward Approach in Cooperative Differential Games
Authors: Ovanes Petrosian
Published: May 2016

New approach to the definition of solution in cooperative differential games is considered. The approach is based on artificially truncated information about the game. It assumed that at each time, instant players have information about the structure of the game (payoff functions, motion equations) only for the next fixed time interval. Based on this information they make the decision. Looking Forward Approach is applied to the cases when the players are not sure about the dynamics of the game on the whole time interval [Formula: see text] and orient themselves on the game dynamics defined on the smaller time interval [Formula: see text] ([Formula: see text]), on which they surely know that the game dynamics is not changing.
A Cooperative Dynamic Environmental Game of Subgame Consistent Clean Technology Development
Authors: Yeung David W. K. , Petrosyan Leon A.
Published: May 2016

Cooperative adoption and development of clean technology play a key role to effectively solving the continual worsening industrial pollution problem. For cooperation over time to be credible, a subgame consistency solution which requires the agreed-upon optimality principle to remain in effect throughout the collaboration duration has to hold. In this paper, we present a cooperative dynamic game of collaborative environmental management with clean technology development. A subgame consistent cooperative scheme is derived. It is the first time that cooperative dynamic environmental games with clean technology development are analyzed. Given that there exist discrete choices of production techniques and switching to clean technology brings about cost savings and improved effectiveness, the group optimal solution cannot be obtained with standard differentiable optimization techniques. To overcome this problem the joint optimal solutions for all the possible patterns of production techniques are computed and the pattern with the highest joint payoff is then selected. The analysis widens the scope of study in collaborative environmental management.
Categorical action of the extended braid group of affine type A
Authors: Gadbled Agnès , Thiel Anne-Laure , Wagner Emmanuel
Published: May 2016

Using a quiver algebra of a double cyclic quiver, we construct a faithful categorical action of the extended braid group of affine type [Formula: see text] on its bounded homotopy category of finitely generated projective modules. The algebra is trigraded and we identify the trigraded dimensions of the space of morphisms of this category with intersection numbers coming from the topological origin of the group.
Local existence, global existence, and scattering for the nonlinear Schrödinger equation
Authors: Cazenave Thierry , Naumkin Ivan
Published: May 2016

In this paper, we construct for every [Formula: see text] and [Formula: see text] a class of initial values [Formula: see text] for which there exists a local solution of the nonlinear Schrödinger equation [Formula: see text] on [Formula: see text] with the initial condition [Formula: see text]. Moreover, we construct for every [Formula: see text] a class of (arbitrarily large) initial values for which there exists a global solution that scatters as [Formula: see text].
N-expansive homeomorphisms on surfaces
Authors: Artigue A. , Pacifico M. J. , Vieitez J. L.
Published: May 2016

In this paper, we study [Formula: see text]-expansive homeomorphisms on surfaces. We prove that when [Formula: see text] is a [Formula: see text]-expansive homeomorphism defined on a compact boundaryless surface [Formula: see text] with non-wandering set [Formula: see text] being the whole of [Formula: see text] then [Formula: see text] is expansive. This condition on the non-wandering set cannot be relaxed: we present an example of a [Formula: see text]-expansive homeomorphisms on a surface with genus [Formula: see text] with wandering points that is not expansive.
Interference Effect on Stationary Aerodynamic Performance between Parallel Bridges
Authors: Zhou Rui , Yang Yongxin , Zhang Lihai , Ge Yaojun
Published: May 2016

During the operation stage, parallel bridges may become nonparallel as a result of unequal load distribution between two parallel bridges and other special conditions. Aerodynamic performance could change significantly under nonparallel positions and become different from that under parallel positions. In this paper, the stationary aerodynamic performance of two parallel bridges under various nonparallel positions during operation stage is studied through a series of wind tunnel tests. This includes the investigation of two horizontal gap distances (HGDs), five relative vertical displacements (RVD) and five relative torsional displacements (RTD). First, sectional models of two closed box girders were tested in smooth flow for stationary aerodynamic force coefficients. An optimum iteration method was then used to calculate the structural displacements and torsional divergence critical wind velocities ([Formula: see text]) of two assumed suspension bridges under stationary aerodynamic force. The research outcomes demonstrated that the changes of stationary aerodynamic force coefficients are dependent on the relative displacements of two girders and wind attack angles. In addition, it was revealed that interference effects are detrimental to stationary aerodynamic instability of two bridges with a larger gap-width ratio (i.e. D/B [Formula: see text] 1), which is related to the aerodynamic shape of girders and bridge structures. Further, the [Formula: see text] of the leeward bridge significantly decline when the vertical position of the leeward bridge become higher that of the windward bridge. Most importantly, it showed that the combination of RVD and RTD (e.g. RVD [Formula: see text][Formula: see text]mm and RTD [Formula: see text]) could potentially lead to the worst stationary aerodynamic performance by decreasing [Formula: see text] of the windward and leeward bridge with 12.03% and 7.89%, respectively.
Geographical Information Systems and Multicriteria Decisions Integration Approach for Hospital Location Selection
Authors: Eldemir Fahrettin , Onden Ismail
Published: May 2016

While establishing a new health facility, such as hospitals, multiple factors should be taken into consideration. Due to the variety, the impacts of these factors on location decision should be evaluated initially. Then, spatial effects of the location factors on the plane should be determined to reach an acceptable decision. These factors can be clustered under the main criteria that are competition, accessibility and environment. Attributable to the problem structure, the decision criteria can be represented with a hierarchical way, and evaluations of the priorities of the decision criteria can be done with the Analytic Hierarchy Process technique. On the other hand, spatial convenient levels of the decision criteria and suitability map can be created with GIS/spatial analysis. Integration of these two different approaches is proposed for locating a new hospital facility. By the integration methodology proposed here, a novel approach for a hospital location decision is brought to the literature. To test the integration process, 13 criteria are determined as decision criteria. Anatolia Region of Istanbul, Turkey is selected as the study area due to the high health care demand in that region. The alternative nodes are found with soil formation considerations. The nodes represented the convenient construction sites for the new facility. After reaching the ideal solution, a sensitivity analysis is conducted on AHP-GIS integration for measuring the effectiveness of the alternative scenarios. After completion of the study, it has been observed that the methodology is capable of measuring the land suitability levels and works with all factors without having any problem.
A Hybrid Artificial Fish Swarm Simulated Annealing Optimization Algorithm for Automatic Identification of Clusters
Authors: He Si , Belacel Nabil , Chan Alan , Hamam Habib , Bouslimani Yassine
Published: May 2016

This paper introduces an alternative fuzzy clustering method that does not require fixing the number of clusters a priori and produce reliable clustering results. This newly proposed method empowers the existing Improved Artificial Fish Swarm algorithm (IAFSA) by the simulated annealing (SA) algorithm. The hybrid approach can prevent IAFSA from unexpected vibration and accelerate convergence rate in the late stage of evolution. Computer simulations are performed to compare this new method with well-known fuzzy clustering algorithms using several synthetic and real-life datasets. Our experimental results show that our newly proposed approach outperforms some other well-known existing fuzzy clustering algorithms in terms of both accuracy and robustness.
Rational Approximations for Heat Radiation and Troesch’s Equations
Authors: Vazquez-Leal Hector , Koçak Hüseyin , Ates Inan
Published: May 2016

In this paper, a new tool for the solution of nonlinear differential equations is presented. It is named rational homotopy perturbation method (RHPM). It delivers a high precision representation of the nonlinear differential equation using a few linear algebraic terms. In order to assess the benefits of this proposal, three nonlinear problems are solved and compared against other semi-analytic methods or numerical methods. Furthermore, in order to deal with BVP problems, we propose a modification of RHPM method. The obtained results show that RHPM is a powerful tool capable to generate highly accurate rational solutions.
Frictional Characteristics of Graphene Layers Using Molecular Dynamics Simulation
Authors: Fang Te-Hua , Chang Win-Jin , Tung Fu-Yung
Published: May 2016

Molecular dynamics simulations of an atomic force microscope (AFM) probe scanning the surface of a five-layer graphene were conducted. The AFM-like scanning probe was modeled by a capped single-wall carbon nanotube. Note that interference with the graphene surface induced frictional behavior; moreover, the effects on the friction system of scanning velocity, probe direction and temperature were investigated. Wrinkling of the graphene surface became more apparent at higher temperatures, while stick-slip friction was more apparent at a lower temperature and a slower scanning velocity. The friction coefficient of the system was approximately 0.001.
High-Frequency Absorption of the Hybrid Composites with Spindle-like Fe3O4 Nanoparticles and Multiwalled Carbon Nanotubes
Authors: Xia Ruozhou , Yin Yichao , Zeng Min , Dong Hangrong , Yang Haozhe , Zeng Xiaojun , Tang Wukui , Yu Ronghai
Published: May 2016

The anisotropic spindle-like Fe3O4 hybrid nanocomposites blended with multi-wall carbon nanotubes (MWCNTs) have been prepared to function as an ideal lightweight candidate for electromagnetic (EM) wave absorption with decent performance in high frequency. The microstructure, morphology, magnetic properties, charge-transfer behavior and EM wave absorbing performance have been characterized by powder X-ray diffractometer, transmission electron microscope, vibrating sample magnetometer, Raman spectrometer and vector network analyzer, respectively. A maximum reflection loss reaches around [Formula: see text]40[Formula: see text]dB with 5% MWCNTs loading density. Compared with the monomer Fe3O4, the complex permittivity and permeability of the Fe3O4–MWCNTs nanocomposites are kept in balance, achieving a better impedance matching with a larger dielectric loss and magnetic loss. The optimization may be attributed to the synergistic effect between spindle-like Fe3O4 nanoparticles and MWCNTs. Moreover, the EM microwave absorbing performance can be optimized by tuning the Fe3O4–MWCNTs mass ratio and layer thickness of the samples, indicating promising application prospects for outstanding performance EM attenuation materials in high frequency.
Structured illumination microscopy and its new developments
Authors: Chen Jianling , Qiu Caimin , You Minghai , Chen Xiaogang , Yang Hongqin , Xie Shusen
Published: May 2016

Optical microscopy allows us to observe the biological structures and processes within living cells. However, the spatial resolution of the optical microscopy is limited to about half of the wavelength by the light diffraction. Structured illumination microscopy (SIM), a type of new emerging super-resolution microscopy, doubles the spatial resolution by illuminating the specimen with a patterned light, and the sample and light source requirements of SIM are not as strict as the other super-resolution microscopy. In addition, SIM is easier to combine with the other imaging techniques to improve their imaging resolution, leading to the developments of diverse types of SIM. SIM has great potential to meet the various requirements of living cells imaging. Here, we review the recent developments of SIM and its combination with other imaging techniques.
Deep belief network-based drug identification using near infrared spectroscopy
Authors: Yang Huihua , Hu Baichao , Pan Xipeng , Yan Shengke , Feng Yanchun , Zhang Xuebo , Yin Lihui , Hu Changqin
Published: May 2016

Near infrared spectroscopy (NIRS) analysis technology, combined with chemometrics, can be effectively used in quick and nondestructive analysis of quality and category. In this paper, an effective drug identification method by using deep belief network (DBN) with dropout mechanism (dropout-DBN) to model NIRS is introduced, in which dropout is employed to overcome the overfitting problem coming from the small sample. This paper tests proposed method under datasets of different sizes with the example of near infrared diffuse reflectance spectroscopy of erythromycin ethylsuccinate drugs and other drugs, aluminum and nonaluminum packaged. Meanwhile, it gives experiments to compare the proposed method’s performance with back propagation (BP) neural network, support vector machines (SVMs) and sparse denoising auto-encoder (SDAE). The results show that for both binary classification and multi-classification, dropout mechanism can improve the classification accuracy, and dropout-DBN can achieve best classification accuracy in almost all cases. SDAE is similar to dropout-DBN in the aspects of classification accuracy and algorithm stability, which are higher than that of BP neural network and SVM methods. In terms of training time, dropout-DBN model is superior to SDAE model, but inferior to BP neural network and SVM methods. Therefore, dropout-DBN can be used as a modeling tool with effective binary and multi-class classification performance on a spectrum sample set of small size.
Perfect codes in poset block spaces
Authors: Dass B. K. , Sharma Namita , Verma Rashmi
Published: May 2016

There is a limited class of perfect codes with respect to the classical Hamming metric. There are other kind of metrics with respect to which perfect codes have been investigated viz. poset metric, block metric and poset block metric. Given the minimal elements of a poset, a necessary and sufficient condition for [Formula: see text]-perfectness of a poset block code has been derived. A necessary and sufficient condition for a poset block code to be [Formula: see text]-perfect has also been considered. Further, for each [Formula: see text], [Formula: see text], a sufficient condition that ensures the existence of a poset block structure which turns a given code into an [Formula: see text]-perfect poset block code has been obtained. Several illustrations of well known codes to be [Formula: see text]-perfect for specific values of [Formula: see text] have been explored.
Minimizing Stack Memory for Hard Real-Time Applications on Multicore Platforms with Partitioned Fixed-Priority or EDF Scheduling
Authors: Wang Chao , Dong Chuansheng , Zeng Haibo , Gu Zonghua
Published: May 2016

Multicore processors are increasingly adopted in resource-constrained real-time embedded applications. In the development of such applications, efficient use of RAM memory is as important as the effective scheduling of software tasks. Preemption Threshold Scheduling (PTS) is a well-known technique for controlling the degree of preemption, possibly improving system schedulability, and to reduce system stack usage. In this paper, we consider partitioned multi-processor scheduling on a multicore processor with either Fixed-Priority or Earliest Deadline First scheduling algorithms with PTS and address the design optimization problem of mapping tasks to processor cores and assignment of task priorities and preemption thresholds with the optimization objective of minimizing system stack usage. We present both optimal solution techniques based on Mixed Integer Linear Programming and efficient heuristic algorithms that can achieve high-quality results. We perform extensive performance evaluations using both synthetic tasksets and industrial case studies.
Live-Out Register Fencing
Authors: Ferreira Ronaldo R. , Nazar Gabriel L. , Rolt Jean Da , Moreira Álvaro F. , Carro Luigi
Published: May 2016

This article introduces Live-Out Register Fencing (LoRF), a soft error correction mechanism that uses the novel
Spill Register File
as a container of checkpointing data. LoRF’s Spill Register File holds the values shared among basic blocks in the program, and, coupled with a new compilation strategy, LoRF allows for error correction in the same basic block where the error was detected. In LoRF, error correction is triggered by a hardware interrupt that restores the registers of a basic block from the Spill Register File. After these registers are restored, the basic block where the error was detected can just be re-executed, thus reducing the costs of error recovery. LoRF’s error correction policy eliminates the need for expensive architectural support for checkpointing and rollback, reducing the performance overhead of online soft error correction. LoRF relies on both a modified processor architecture and a corresponding compiler. The architecture was implemented in synthesizable VHDL, whereas the compiler was developed as an extension of the LLVM framework. Fault injection experiments support an error correction coverage of 99.35% and a mean performance overhead of 1.33 for the entire life cycle of an error from its occurrence to its elimination from the system.
Rethinking Computer Architectures and Software Systems for Phase-Change Memory
Authors: Wu Chengwen , Zhang Guangyan , Li Keqin
Published: May 2016

With dramatic growth of data and rapid enhancement of computing powers, data accesses become the bottleneck restricting overall performance of a computer system. Emerging phase-change memory (PCM) is byte-addressable like DRAM, persistent like hard disks and Flash SSD, and about four orders of magnitude faster than hard disks or Flash SSDs for typical file system I/Os. The maturity of PCM from research to production provides a new opportunity for improving the I/O performance of a system. However, PCM also has some weaknesses, for example, long write latency, limited write endurance, and high active energy. Existing processor cache systems, main memory systems, and online storage systems are unable to leverage the advantages of PCM, and/or to mitigate PCM’s drawbacks. The reason behind this incompetence is that they are designed and optimized for SRAM, DRAM memory, and hard drives, respectively, instead of PCM memory. There have been some efforts concentrating on rethinking computer architectures and software systems for PCM. This article presents a detailed survey and review of the areas of computer architecture and software systems that are oriented to PCM devices. First, we identify key technical challenges that need to be addressed before this memory technology can be leveraged, in the form of processor cache, main memory, and online storage, to build high-performance computer systems. Second, we examine various designs of computer architectures and software systems that are PCM aware. Finally, we obtain several helpful observations and propose a few suggestions on how to leverage PCM to optimize the performance of a computer system.
Insights from Mining Eleven Years of Scholarly Paper Publications in Requirements Engineering (RE) Series of Conferences
Authors: Sharma Richa , Aggarwal Peeyush , Sureka Ashish
Published: May 2016

We present insights from a bibliometric analysis and scientific paper publication mining of 551 papers in Requirements Engineering (RE) series of conference (11 years from 2005 to 2015). We study cross-disciplinary and interdisciplinary nature of RE re- search by analyzing the cited disciplines in the reference section of each paper. We apply topic modeling on a corpus consisting of 551 abstracts and extract topics as frequently co-occurring and connected terms. We use topic modeling to study the structure and composition of RE research and analyze popular topics in industry as well as research track. Co-authorship in papers is an indicator of collaboration and interaction between scientists as well as institutions and we analyze co-authorship data to in- vestigate university-industry collaboration, internal and external collaborations. We present results on the distribution of the num- ber of co-authors in each paper as well as distribution of authors across world regions. We present our analysis on the public or proprietary dataset as well as the domain of the dataset used in studies published in Requirements Engineering (RE) series of conferences.
Improved GUI Testing using Task Parallel Library
Authors: Öztürk Muhammed Maruf , Zengin Ahmet
Published: May 2016

While performing a software engineering project, testing is one of the effort intensive activity accounting for up to 50% of total software development cost. To reduce this cost, parallel execution of test cases is a preferred way for developers. Task Parallel Library (TPL) is a powerful and scalable library providing a wide range of methods while facilitating test harnesses. Here, we propose a novel algorithm P-GUI, thereby using TPL. Results of experiment designed on 10 web pages show that proposed algorithm achieved a speedup of 1.4 on average.
Structural Properties of Nonautoreducible Sets
Authors: Nguyen Dung , Selman Alan L.
Published: May 2016

We investigate autoreducibility properties of complete sets for NEXP under different polynomial-time reductions. Specifically, we show under some polynomial-time reductions that there are complete sets for NEXP that are not autoreducible. We obtain the following main results:

—For any positive integers
s
and
k
such that 2

s

− 1 >
k
, there is a ≤
s-T
p
-complete set for NEXP that is not ≤
k-tt
p
-autoreducible.

—For every constant
c
> 1, there is a ≤
2-T
p
-complete set for NEXP that is not autoreducible under nonadaptive reductions that make no more than three queries, such that each of them has a length between
n
1/c
and

n
c

, where
n
is input size.

—For any positive integer
k
, there is a ≤
k-tt
p
-complete set for NEXP that is not autoreducible under ≤
k-tt
p
-reductions whose truth table is not a disjunction or a negated disjunction.

Finally, we show that settling the question of whether every ≤
dtt
p
-complete set for NEXP is ≤
NOR-tt
p
-autoreducible either positively or negatively would lead to major results about the exponential time complexity classes.
Random Walk with Restart on Large Graphs Using Block Elimination
Authors: Jung Jinhong , Shin Kijung , Sael Lee , Kang U
Published: May 2016

Given a large graph, how can we calculate the relevance between nodes fast and accurately? Random walk with restart (RWR) provides a good measure for this purpose and has been applied to diverse data mining applications including ranking, community detection, link prediction, and anomaly detection. Since calculating RWR from scratch takes a long time, various preprocessing methods, most of which are related to inverting adjacency matrices, have been proposed to speed up the calculation. However, these methods do not scale to large graphs because they usually produce large dense matrices that do not fit into memory. In addition, the existing methods are inappropriate when graphs dynamically change because the expensive preprocessing task needs to be computed repeatedly.

In this article, we propose B
ear
, a fast, scalable, and accurate method for computing RWR on large graphs. B
ear
has two versions: a preprocessing method B
ear
S for static graphs and an incremental update method B
ear
D for dynamic graphs. B
ear
S consists of the preprocessing step and the query step. In the preprocessing step, B
ear
S reorders the adjacency matrix of a given graph so that it contains a large and easy-to-invert submatrix, and precomputes several matrices including the Schur complement of the submatrix. In the query step, B
ear
S quickly computes the RWR scores for a given query node using a block elimination approach with the matrices computed in the preprocessing step. For dynamic graphs, B
ear
D efficiently updates the changed parts in the preprocessed matrices of B
ear
S based on the observation that only small parts of the preprocessed matrices change when few edges are inserted or deleted. Through extensive experiments, we show that B
ear
S significantly outperforms other state-of-the-art methods in terms of preprocessing and query speed, space efficiency, and accuracy. We also show that B
ear
D quickly updates the preprocessed matrices and immediately computes queries when the graph changes.
Capturing Missing Tuples and Missing Values
Authors: Deng Ting , Fan Wenfei , Geerts Floris
Published: May 2016

Databases in real life are often neither entirely closed-world nor entirely open-world. Databases in an enterprise are typically
partially closed
, in which a part of the data is constrained by master data that contains complete information about the enterprise in certain aspects. It has been shown that, despite missing tuples, such a database may turn out to have complete information for answering a query.

This article studies partially closed databases from which
both tuples and attribute values
may be missing. We specify such a database in terms of conditional tables constrained by master data, referred to as
c
-instances. We first propose three models to characterize whether a
c
-instance
T
is
complete
for a query
Q
relative to
master data. That is, depending on how missing values in
T
are instantiated, the answer to
Q
in
T
remains unchanged when new tuples are added. We then investigate three problems, to determine (a) whether a given
c
-instance is complete for a query
Q
, (b) whether there exists a
c
-instance that is complete for
Q
relative to master data available, and (c) whether a
c
-instance is a minimal-size database that is complete for
Q
. We establish matching lower and upper bounds on these problems for queries expressed in a variety of languages in each of the three models for specifying relative completeness.
Changing the Game
Authors: Tichy Walter
Published: May 2016

Dave Schrader, known to his friends as Dr. Dave, worked for 24 years in advanced development and marketing at Teradata, a major data warehouse vendor. He actively gives talks on business analytics, and since retiring has spent time exploring the field of sports analytics. In this interview, Schrader discusses how analytics is playing a significant role in professional sports--from Major League Soccer to the NBA.
Gradual certified programming in coq
Authors: Tanter Éric , Tabareau Nicolas
Published: May 2016

Expressive static typing disciplines are a powerful way to achieve high-quality software. However, the adoption cost of such techniques should not be under-estimated. Just like gradual typing allows for a smooth transition from dynamically-typed to statically-typed programs, it seems desirable to support a gradual path to certified programming. We explore gradual certified programming in Coq, providing the possibility to postpone the proofs of selected properties, and to check "at runtime" whether the properties actually hold. Casts can be integrated with the implicit coercion mechanism of Coq to support implicit cast insertion à la gradual typing. Additionally, when extracting Coq functions to mainstream languages, our encoding of casts supports lifting assumed properties into runtime checks. Much to our surprise, it is not necessary to extend Coq in any way to support gradual certified programming. A simple mix of type classes and axioms makes it possible to bring gradual certified programming to Coq in a straightforward manner.
High-performance cross-language interoperability in a multi-language runtime
Authors: Grimmer Matthias , Seaton Chris , Schatz Roland , Würthinger Thomas , Mössenböck Hanspeter
Published: May 2016

Programmers combine different programming languages because it allows them to use the most suitable language for a given problem, to gradually migrate existing projects from one language to another, or to reuse existing source code. However, existing cross-language mechanisms suffer from complex interfaces, insufficient flexibility, or poor performance. We present the TruffleVM, a multi-language runtime that allows composing different language implementations in a seamless way. It reduces the amount of required boiler-plate code to a minimum by allowing programmers to access foreign functions or objects by using the notation of the host language. We compose language implementations that translate source code to an intermediate representation (IR), which is executed on top of a shared runtime system. Language implementations use language-independent messages that the runtime resolves at their first execution by transforming them to efficient foreign-language-specific operations. The TruffleVM avoids conversion or marshaling of foreign objects at the language boundary and allows the dynamic compiler to perform its optimizations across language boundaries, which guarantees high performance. This paper presents an implementation of our ideas based on the Truffle system and its guest language implementations JavaScript, Ruby, and C.
Language-independent storage strategies for tracing-JIT-based virtual machines
Authors: Pape Tobias , Felgentreff Tim , Hirschfeld Robert , Gulenko Anton , Bolz Carl Friedrich
Published: May 2016

Storage strategies have been proposed as a run-time optimization for the PyPy Python implementation and have shown promising results for optimizing execution speed and memory requirements. However, it remained unclear whether the approach works equally well in other dynamic languages. Furthermore, while PyPy is based on RPython, a language to write VMs with reusable components such as a tracing just-in-time compiler and garbage collection, the strategies design itself was not generalized to be reusable across languages implemented using that same toolchain. In this paper, we present a general design and implementation for storage strategies and show how they can be reused across different RPython-based languages. We evaluate the performance of our implementation for RSqueak, an RPython-based VM for Squeak/Smalltalk and show that storage strategies may indeed offer performance benefits for certain workloads in other dynamic programming languages.We furthermore evaluate the generality of our implementation by applying it to Topaz, a Ruby VM, and Pycket, a Racket implementation.
The next-generation in-stadium experience (keynote)
Authors: Narasimhan Priya , Drolia Utsav , Tan Jiaqi , Mickulicz Nathan D. , Gandhi Rajeev
Published: May 2016

YinzCam is a cloud-hosted service that provides sports fans with real-time scores, news, photos, statistics, live radio, streaming video, etc., on their mobile devices. YinzCam’s infrastructure is currently hosted on Amazon Web Services (AWS) and supports over 30 million installs of the official mobile apps of 140+ NHL/NFL/NBA/NRL/NCAA sports teams and venues. YinzCam’s workload is necessarily multi-modal (e.g., pre-game, in-game, post-game, game-day, non-gameday), with normal game-time traffic being twenty-fold of that on non-game days. This paper describes the evolution of YinzCam’s production architecture and distributed infrastructure, from its beginnings in 2009, when it was used to support thousands of concurrent users, to today’s system that supports millions of concurrent users on any game day. We also discuss key new opportunities to improve the fan experience inside the stadium of the future, without impacting the available bandwidth, by crowd-sourcing the thousands of mobile devices that are in fans’ hands inside these venues. We present Krowd, a novel distributed key-value store for promoting efficient content sharing, discovery and retrieval across the mobile devices inside a stadium. We present CHIPS, a system that ensures that users’ privacy is maintained while their devices participate in the crowdsourced infrastructure.
An empirical study on configuration-related issues: investigating undeclared and unused identifiers
Authors: Medeiros Flávio , Rodrigues Iran , Ribeiro Márcio , Teixeira Leopoldo , Gheyi Rohit
Published: May 2016

The variability of configurable systems may lead to configuration-related issues (i.e., faults and warnings) that appear only when we select certain configuration options. Previous studies found that issues related to configurability are harder to detect than issues that appear in all configurations, because variability increases the complexity. However, little effort has been put into understanding configuration-related faults (e.g., undeclared functions and variables) and warnings (e.g., unused functions and variables). To better understand the peculiarities of configuration-related undeclared/unused variables and functions, in this paper we perform an empirical study of 15 systems to answer research questions related to how developers introduce these issues, the number of configuration options involved, and the time that these issues remain in source files. To make the analysis of several projects feasible, we propose a strategy that minimizes the initial setup problems of variability-aware tools. We detect and confirm 2 undeclared variables, 14 undeclared functions, 16 unused variables, and 7 unused functions related to configurability. We submit 30 patches to fix issues not fixed by developers. Our findings support the effectiveness of sampling (i.e., analysis of only a subset of valid configurations) because most issues involve two or less configuration options. Nevertheless, by analyzing the version history of the projects, we observe that a number of issues remain in the code for several years. Furthermore, the corpus of undeclared/unused variables and functions gathered is a valuable source to study these issues, compare sampling algorithms, and test and improve variability-aware tools.
Modular interpreters for the masses: implicit context propagation using object algebras
Authors: Inostroza Pablo , Storm Tijs van der
Published: May 2016

Modular interpreters have the potential to achieve component-based language development: instead of writing language interpreters from scratch, they can be assembled from reusable, semantic building blocks. Unfortunately, traditional language interpreters are hard to extend because different language constructs may require different interpreter signatures. For instance, arithmetic interpreters produce a value without any context information, whereas binding constructs require an additional environment. In this paper, we present a practical solution to this problem based on implicit context propagation. By structuring denotational-style interpreters as Object Algebras, base interpreters can be retroactively lifted into new interpreters that have an extended signature. The additional parameters are implicitly propagated behind the scenes, through the evaluation of the base interpreter. Interpreter lifting enables a flexible style of component-based language development. The technique works in mainstream object-oriented languages, does not sacrifice type safety or separate compilation, and can be easily automated. We illustrate implicit context propagation using a modular definition of Featherweight Java and its extension to support side-effects.
Safer SDN programming through Arbiter
Authors: Lopez Michael , Casey C. Jasson , Reis Gabriel Dos , Chojnacki Colton
Published: May 2016

Software Defined Networking (SDN) programs are written with respect to assumptions on software and hardware facilities and protocol definitions. Silent mismatches between the expected feature set and implemented feature set of SDN artifacts can easily lead to hard to debug network configurations, decreased network performance, outages, or worse, security vulnerabilities. We show how the paradigm of axiomatic programming, supported by practical dependent types, provides effective support for SDN executable specifications and verification.​
Generating safe boundary APIs between typed EDSLs and their environments
Authors: Reynders Bob , Devriese Dominique , Piessens Frank
Published: May 2016

Embedded domain specific languages (EDSLs) are used to represent special-purpose code in a general-purpose language and they are used for applications like vector calculations and run-time code generation. Often, code in an EDSL is compiled to a target (e.g. GPU languages, JVM bytecode, assembly, JavaScript) and needs to interface with other code that is available at that level but uses other data representations or calling conventions. We present an approach for safely making available such APIs in a typed EDSL, guaranteeing correct conversions between data representations and the respect for calling conventions. When the code being interfaced with is the result of static compilation of host language code, we propose a way to auto-generate the needed boilerplate using meta-programming. We instantiate our technique with JavaScript as the target language, JS-Scala as the EDSL, Scala.js as the static compiler and Scala macros to generate the boilerplate, but our design is more generally applicable. We provide evidence of usefulness of our approach through a prototype implementation that we have applied in a non-trivial code base.
POP-PL: a patient-oriented prescription programming language
Authors: Florence Spencer P. , Fetscher Bruke , Flatt Matthew , Temps William H. , Kiguradze Tina , West Dennis P. , Niznik Charlotte , Yarnold Paul R. , Findler Robert Bruce , Belknap Steven M.
Published: May 2016

Medical professionals have long used algorithmic thinking to describe and implement health care processes without the benefit of the conceptual framework provided by a programming language. Instead, medical algorithms are expressed using English, flowcharts, or data tables. This results in prescriptions that are difficult to understand, hard to debug, and awkward to reuse. This paper reports on the design and evaluation of a domain-specific programming language, POP-PL for expressing medical algorithms. The design draws on the experience of researchers in two disciplines, programming languages and medicine. The language is based around the idea that programs and humans have complementary strengths, that when combined can make for safer, more accurate performance of prescriptions. We implemented a prototype of our language and evaluated its design by writing prescriptions in the new language and administering a usability survey to medical professionals. This formative evaluation suggests that medical prescriptions can be conveyed by a programming language's mode of expression and provides useful information for refining the language. Analysis of the survey results suggests that medical professionals can understand and correctly modify programs in POP-PL.
Composing code generators for C&C ADLs with Application-specific behavior languages (tool demonstration)
Authors: Ringert Jan Oliver , Rumpe Bernhard , Wortmann Andreas
Published: May 2016

Modeling software systems as component & connector architectures with application-specific behavior modeling languages enables domain experts to describe each component behavior with the most appropriate language. Generating executable systems for such language aggregates requires composing appropriate code generators for the participating languages. Previous work on code generator composition either focuses on white-box integration based on code generator internals or requires extensive handcrafting of integration code. We demonstrate an approach to black-box generator composition for architecture description languages that relies on explicit interfaces and exploits the encapsulation of components. This approach is implemented for the architecture modeling framework MontiArcAutomaton and has been evaluated in various contexts. Ultimately, black-box code generator composition facilitates development of code generators for architecture description languages with embedded behavior languages and increases code generator reuse.
Model querying with query models
Authors: Noguera Carlos , Jonckers Viviane
Published: May 2016

Model querying is an integral part of Model-Driven Engineering. Developers query models when specifying model transformations, when defining model constraints, or simply when they need to extract some information from the model. Model queries are often specified in a general-purpose programming language, with developers just navigating models through their programming interfaces. OCL is the best known model query language, and while successful, it is difficult to express complex structural properties featured in target model elements. In this paper we describe a model query facility that aims at easing the description of structural features in a query. In our approach, developers model their queries by reusing fragments of the target model to specify the invariant parts of the template, augmented with variables and special relations to specify what can vary. The query itself conforms to a meta-model that extends the meta-model under-query. By reusing the queried meta- model developers can reduce the mental overhead that comes from using a different language to specify the queries. We have developed a proof of concept tool for the Eclipse Modeling Framework (EMF) that (1) generates a query meta-model from a target meta- model, (2) allows the construction of queries using a graphical, graph-based editor and (3) executes the queries by translating them to a set of logic predicates that are then evaluated using an extension of the logic-based query language Ekeko.