Bolivian Private University, Cochabamba
Cochabamba, Bolivia
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Marek L.,Charles University | Villazon A.,Bolivian Private University, Cochabamba | Zheng Y.,Shanghai JiaoTong University | Ansaloni D.,University of Lugano | And 2 more authors.
AOSD'12 - Proceedings of the 11th Annual International Conference on Aspect Oriented Software Development | Year: 2012

Many dynamic analysis tools for programs written in managed languages such as Java rely on bytecode instrumentation. Tool development is often tedious because of the use of low-level bytecode manipulation libraries. While aspect-oriented programming (AOP) offers high-level abstractions to concisely express certain dynamic analyses, the join point model of mainstream AOP languages such as AspectJ is not well suited for many analysis tasks and the code generated by weavers in support of certain language features incurs high overhead. In this paper we introduce DiSL (domain-specific language for instrumentation), a new language especially designed for dynamic program analysis. DiSL offers an open join point model where any region of byte-codes can be a shadow, synthetic local variables for efficient data passing, efficient access to comprehensive static and dynamic context information, and weave-time execution of user-defined static analysis code. We demonstrate the benefits of DiSL with a case study, recasting an existing dynamic analysis tool originally implemented in AspectJ. We show that the DiSL version offers better code coverage, incurs significantly less overhead, and eases the integration of new analysis features that could not be expressed in AspectJ. © 2012 ACM.

Moret P.,University of Lugano | Binder W.,University of Lugano | Villazon A.,Bolivian Private University, Cochabamba | Ansaloni D.,University of Lugano | Heydarnoori A.,University of Lugano
Software - Practice and Experience | Year: 2010

Calling context profiling is an important technique for analyzing the performance of object-oriented software with complex inter-procedural control flow. The Calling Context Tree (CCT) is a common data structure that stores dynamic metrics, such as CPU time, separately for each calling context. As CCTs may comprise millions of nodes, there is a need for a condensed visualization that eases the localization of performance bottlenecks. In this article, we discuss Calling Context Ring Charts (CCRCs), a compact visualization for CCTs, where callee methods are represented in ring segments surrounding the caller's ring segment. In order to reveal hot methods, their callers, and callees, the ring segments can be sized according to a chosen dynamic metric. We describe two case studies where CCRCs help us to detect and fix performance problems in applications. A performance evaluation also confirms that our implementation can efficiently handle large CCTs. Copyright © 2010 John Wiley & Sons, Ltd.

Palacios-Marques D.,Polytechnic University of Valencia | Saldana A.Z.,Bolivian Private University, Cochabamba | Vila J.E.,University of Valencia
Kybernetes | Year: 2013

Purpose: Firms are adopting Web 2.0 technologies to improve collaboration, participation and communication; however there are few empirical studies testing the impact of this adoption. The purpose of this article is to analyze if there is a linkage amongst market orientation, Web 2.0 adoption and innovativeness. Design/methodology/approach: Structural equation modeling was used to test the relationships amongst the variables. A sample of 244 firms of the hospitality industry was used. The theoretical approach is based on the market orientation and innovativeness, concepts, which have been studied by various authors in the literature. Findings: A positive relationship was found between market orientation and Web 2.0 adoption and between Web 2.0 adoption and innovativeness. Research limitations/implications: The study was developed in one industry, so in order to generalize the findings, additional testing in other industries should be developed. In addition a longitudinal study is encouraged. Practical implications: Managers are advised to adopt Web 2.0 technologies to strengthen market orientation behaviors and innovativeness. Originality/value: This article empirically tested the relationship between market orientation and Web 2.0 adoption and the impact of Web 2.0 adoption on innovativeness. Although some managers and researchers have reported some positive impacts of Web 2.0 on different aspects of the organization, there are still few empirical studies, and the authors contributed to fill this void. © Emerald Group Publishing Limited.

Schoeberl M.,Technical University of Denmark | Binder W.,University of Lugano | Villazon A.,Bolivian Private University, Cochabamba
Proceedings - 2011 14th IEEE International Symposium on Object/Component/Service-Oriented Real-Time Distributed Computing, ISORC 2011 | Year: 2011

To avoid data cache trashing between heap-allocated data and other data areas, a distinct object cache has been proposed for embedded real-time Java processors. This object cache uses high associativity in order to statically track different object pointers for worst-case execution-time analysis. However, before implementing such an object cache, an empirical analysis of different organization forms is needed. We use a cross-profiling technique based on aspect-oriented programming in order to evaluate different object cache organizations with standard Java benchmarks. From the evaluation we conclude that field access exhibits some temporal locality, but almost no spatial locality. Therefore, filling long cache lines on a miss just introduces a high miss penalty without increasing the hit rate enough to make up for the increased miss penalty. For an object cache, it is more efficient to fill individual words within the cache line on a miss. © 2011 IEEE.

Marechal A.,Bolivian Private University, Cochabamba | Marechal A.,University of Geneva | Buchs D.,University of Geneva
Fundamenta Informaticae | Year: 2015

Modularity is a mandatory principle to apply Petri nets to real world-sized systems. Modular extensions of Petri nets allow to create complex models by combining smaller entities. They facilitate the modeling and verification of large systems by applying a divide and conquer approach and promoting reuse. Modularity includes a wide range of notions such as encapsulation, hierarchy and instantiation. Over the years, Petri nets have been extended to include these mechanisms in many different ways. The heterogeneity of such extensions and their definitions makes it difficult to reason about their common features at a general level. We propose in this article an approach to standardize the semantics of modular Petri nets formalisms, with the objective of gathering even the most complex modular features from the literature. This is achieved with a new Petri nets formalism, called the LLAMAS Language for Advanced Modular Algebraic Nets (LLAMAS). We focus principally on the composition mechanism of LLAMAS, while introducing the rest of the language with an example. The composition mechanism is introduced both informally and with formal definitions. Our approach has two positive outcomes. First, the definition of new formalisms is facilitated, by providing common ground for the definition of their semantics. Second, it is possible to reason at a general level on the most advanced verification techniques, such as the recent advances in the domain of decision diagrams. © 2015, ISO Press. All rights reserved.

Villazon A.,University of Lugano | Villazon A.,Bolivian Private University, Cochabamba | Binder W.,University of Lugano | Moret P.,University of Lugano | Ansaloni D.,University of Lugano
Science of Computer Programming | Year: 2011

Aspect-oriented programming (AOP) has been successfully applied to application code thanks to techniques such as Java bytecode instrumentation. Unfortunately, with existing AOP frameworks for Java such as AspectJ, aspects cannot be woven into the standard Java class library. This restriction is particularly unfortunate for aspects that would benefit from comprehensive aspect weaving with complete method coverage, such as profiling or debugging aspects. In this article we present MAJOR, a new tool for comprehensive aspect weaving, which ensures that aspects are woven into all classes loaded in a Java Virtual Machine, including those in the standard Java class library. MAJOR includes the pluggable module CARAJillo, which supports efficient access to a complete and customizable calling context representation. We validate our approach with three case studies. Firstly, we weave existing profiling aspects with MAJOR which otherwise would generate incomplete profiles. Secondly, we introduce an aspect for memory leak detection that also benefits from comprehensive weaving. Thirdly, we present an aspect subsuming the functionality of ReCrash, an existing tool based on low-level bytecode instrumentation techniques that generates unit tests to reproduce program failures. Our aspect-based tools are concisely implemented in a few lines of code, and leverage MAJOR and CARAJillo for comprehensive aspect weaving and for efficient access to calling context information. © 2011 Elsevier B.V. All rights reserved.

Binder W.,University of Lugano | Ansaloni D.,University of Lugano | Villazon A.,Bolivian Private University, Cochabamba | Moret P.,University of Lugano
Concurrency Computation Practice and Experience | Year: 2011

Many profilers for virtual execution environments, such as the Java virtual machine (JVM), are implemented with low-level bytecode instrumentation techniques, which is tedious, error-prone, and complicates maintenance and extension of the tools. In order to reduce the development time and cost, we promote building profilers for the JVM using high-level aspect-oriented programming (AOP). We show that the use of aspects yields concise profilers that are easy to develop, extend, and maintain, because low-level instrumentation details are hidden from the tool developer. In order to build efficient profilers, we introduce inter-advice communication, an extension to common AOP languages that enables efficient data passing between advices that are woven into the same method using local variables. We illustrate our approach with two case studies. First, we show that an existing, instrumentation-based tool for listener latency profiling can be easily recast as an aspect. Second, we present an aspect for comprehensive calling context profiling. In order to reduce profiling overhead, our aspect parallelizes application execution and profile creation, resulting in a speedup of 110% on a machine with more than two cores, compared with a primitive, non-parallel approach. Copyright © 2011 John Wiley & Sons, Ltd.

Bell K.R.W.,University of Strathclyde | Nedic D.P.,Siemens AG | Salinas San Martin L.A.,Bolivian Private University, Cochabamba
IEEE Transactions on Sustainable Energy | Year: 2012

This paper describes a study conducted to address the question of how much power transfer capacity should be provided on a meshed transmission system to maintain reliability of supply to consumers in the presence of wind generation. A simulation methodology is presented that includes modeling of the available wind generation in the longer term across a quite large area taking into account correlations in available power between different locations in that area. A description is given of the results obtained in characterization of the relationship between the peak load in an area, the total generation capacity in that area, the proportion of it that is wind generation, and how much transmission import capability - "interconnection reserve" - is required for a given reliability of supply. Finally, a number of issues faced by power system investment planners are discussed and pointers given to further work to enable transmission utilities to meet the challenges presented by policy makers in respect of development of wind power to meet renewable energy targets. © 2010-2012 IEEE.

Rothlisberger D.,University of Bern | Harry M.,University of Bern | Binder W.,University of Lugano | Moret P.,University of Lugano | And 3 more authors.
IEEE Transactions on Software Engineering | Year: 2012

Modern IDEs such as Eclipse offer static views of the source code, but such views ignore information about the runtime behavior of software systems. Since typical object-oriented systems make heavy use of polymorphism and dynamic binding, static views will miss key information about the runtime architecture. In this paper, we present an approach to gather and integrate dynamic information in the Eclipse IDE with the goal of better supporting typical software maintenance activities. By means of a controlled experiment with 30 professional developers, we show that for typical software maintenance tasks, integrating dynamic information into the Eclipse IDE yields a significant 17.5 percent decrease of time spent while significantly increasing the correctness of the solutions by 33.5 percent. We also provide a comprehensive performance evaluation of our approach. © 2012 IEEE.

Brennan M.P.,Michigan Technological University | Abramase A.L.,Bolivian Private University, Cochabamba | Andrews R.W.,Queen's University | Pearce J.M.,Michigan Technological University
Solar Energy Materials and Solar Cells | Year: 2014

Although the spectral effects of direct and diffuse radiation on solar photovoltaic (PV) performance are relatively well understood, recent investigations have shown that there can be a spectral bias introduced due to albedo from common ground surfaces that can impact the optimal selection of PV materials for a known location. This paper extends analysis to the effects of spectral bias due to the specular reflectivity of 22 commonly occurring surface materials (both man-made and natural) and analyzes the albedo effects on the performance of seven PV materials covering three common PV system topologies: industrial (solar farms), commercial flat rooftops and residential pitched roof applications. An effective albedo is found for each surface material and PV material combination, which can be used in lieu of broadband albedo values in PV simulations. These results enable PV material selection for specific environments enabling geographic optimization for the micro-environment, while at the same time assisting optimal surface selection in the vicinity of existing or planned PV arrays. This analysis is of particular significance for the modeling of performance of bi-facial PV modules and vertical BIPV. © 2014 Elsevier B.V.

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