Longitudinal Analysis of Technical Debt for Strategic Platform Adoption

Increasingly, software producing organizations utilize a common software platform, joining an ecosystem; however, little expertise exists on selecting which platform to use when presented a number of different platforms. While technical debt can be used to examine the quality of a software platform by the organization that produces the software, a single discrete data point does not provide sufficient context for analysis. In this paper, we seek to resolve this difficulty by applying linear regression analysis to technical debt data collected by the SonarQube static analyzer. We apply this method to a case study on Cytoscape network analysis platform to perform a pedagogical investigation on the longitudinal technical debt found in that platform. We present our case study on the longitudinal technical debt in the form of arguments for and against the adoption of the Cytoscape network analysis platform, utilizing the data and analysis generated from our method

Whole-System Worst-Case Energy-Consumption Analysis for Energy-Constrained Real-Time Systems

Although internal devices (e.g., memory, timers) and external devices (e.g., transceivers, sensors) significantly contribute to the energy consumption of an embedded real-time system, their impact on the worst-case response energy consumption (WCRE) of tasks is usually not adequately taken into account. Most WCRE analysis techniques, for example, only focus on the processor and therefore do not consider the energy consumption of other hardware units. Apart from that, the typical approach for dealing with devices is to assume that all of them are always activated, which leads to high WCRE overestimations in the general case where a system switches off the devices that are currently not needed in order to minimize energy consumption. In this paper, we present SysWCEC, an approach that addresses these problems by enabling static WCRE analysis for entire real-time systems, including internal as well as external devices. For this purpose, SysWCEC introduces a novel abstraction, the power-state-transition graph, which contains information about the worst-case energy consumption of all possible execution paths. To construct the graph, SysWCEC decomposes the analyzed real-time system into blocks during which the set of active devices in the system does not change and is consequently able to precisely handle devices being dynamically activated or deactivated

SoftSystem: Smart Edge Computing Device Selection Method for IoT Based on Soft Set Technique

The Internet of Things (IoT) is growing day by day, and new IoT devices are introduced and interconnected. Due to this rapid growth, IoT faces several issues related to communication in the edge computing network. The critical issue in these networks is the effective edge computing IoT device selection whenever there are several edge nodes to carry information. To overcome this problem, in this paper, we proposed a new framework model named SoftSystem based on the soft set technique that recommends useful IIoT devices. Then, we proposed an algorithm named Softsystemalgo. For the proposed system, three different parameters are selected: IoT Device Security (IDSC), IoT Device Storage (IDST), and IoT Device Communication Speed (IDCS). We also find out the most significant parameters from the given set of parameters. It is evident that our proposed system is effective for the selection of edge computing devices in the IoT network

Virtual HSM: Building a Hardware-backed Dependable Cryptographic Store

Cloud computing is being used by almost everyone, from regular consumer to IT specialists, as it is a way to have high availability, geo-replication, and resource elasticity with pay-as-you-go charging models. Another benefit is the minimal management effort and maintenance expenses for its users. However, security is still pointed out as the main reason hindering the full adoption of cloud services. Consumers lose ownership of their data as soon as it goes to the cloud; therefore, they have to rely on cloud provider’s security assumptions and Service Level Agreements regarding privacy and integrity guarantees for their data. Hardware Security Modules (HSMs) are dedicated cryptographic processors, typically used in secure cloud applications, that are designed specifically for the protection of cryptographic keys in all steps of their life cycles. They are physical devices with tamperproof resistance, but rather expensive. There have been some attempts to virtualize HSMs. Virtual solutions can reduce its costs but without much success as performance is incomparable and security guarantees are hard to achieve in software implementations. In this dissertation, we aim at developing a virtualized HSM supported by modern attestation-based trusted hardware in commodity CPUs to ensure privacy and reliability, which are the main requirements of an HSM. High availability will also be achieved through techniques such as cloud-of-clouds replication on top of those nodes. Therefore virtual HSMs, on the cloud, backed with trusted hardware, seem increasingly promising as security, attestation, and high availability will be guaranteed by our solution, and it would be much cheaper and as reliable as having physical HSMs

Walk line drawing

The idea is to suggest a hiking trip or a city sightseeing tour based on an input line drawing. The program should evaluate the plausibility of walking a certain trail defined by the line drawing and suggest a place in a predefined geographical region to carry out the walk. Furthermore the application should be used during the hike for navigating and capturing the trail.La idea es sugerir un viaje de senderismo o un recorrido por la ciudad basado en un dibujo de línea de entrada. El programa debe evaluar la plausibilidad de caminar un cierto sendero definido por el dibujo lineal y sugerir un lugar en una región geográfica predefinida para realizar la caminata. Además, la aplicación debe utilizarse durante la caminata para navegar y capturar el sendero.La idea és suggerir un viatge de senderisme o un recorregut per la ciutat basat en un dibuix de línia d'entrada. El programa ha d'avaluar la plausibilitat de caminar una certa sender definit pel dibuix lineal i suggerir un lloc en una regió geogràfica predefinida per realitzar la caminada. A més, l'aplicació s'ha d'utilitzar durant la caminada per navegar i capturar la sendera

Exploring Written Artefacts

This collection, presented to Michael Friedrich in honour of his academic career at of the Centre for the Study of Manuscript Cultures, traces key concepts that scholars associated with the Centre have developed and refined for the systematic study of manuscript cultures. At the same time, the contributions showcase the possibilities of expanding the traditional subject of ‘manuscripts’ to the larger perspective of ‘written artefacts’

Automating Topology Aware Mapping for Supercomputers

Petascale machines with hundreds of thousands of cores are being built. These machines have varying interconnect topologies and large network diameters. Computation is cheap and communication on the network is becoming the bottleneck for scaling of parallel applications. Network contention, specifically, is becoming an increasingly important factor affecting overall performance. The broad goal of this dissertation is performance optimization of parallel applications through reduction of network contention. Most parallel applications have a certain communication topology. Mapping of tasks in a parallel application based on their communication graph, to the physical processors on a machine can potentially lead to performance improvements. Mapping of the communication graph for an application on to the interconnect topology of a machine while trying to localize communication is the research problem under consideration. The farther different messages travel on the network, greater is the chance of resource sharing between messages. This can create contention on the network for networks commonly used today. Evaluative studies in this dissertation show that on IBM Blue Gene and Cray XT machines, message latencies can be severely affected under contention. Realizing this fact, application developers have started paying attention to the mapping of tasks to physical processors to minimize contention. Placement of communicating tasks on nearby physical processors can minimize the distance traveled by messages and reduce the chances of contention. Performance improvements through topology aware placement for applications such as NAMD and OpenAtom are used to motivate this work. Building on these ideas, the dissertation proposes algorithms and techniques for automatic mapping of parallel applications to relieve the application developers of this burden. The effect of contention on message latencies is studied in depth to guide the design of mapping algorithms. The hop-bytes metric is proposed for the evaluation of mapping algorithms as a better metric than the previously used maximum dilation metric. The main focus of this dissertation is on developing topology aware mapping algorithms for parallel applications with regular and irregular communication patterns. The automatic mapping framework is a suite of such algorithms with capabilities to choose the best mapping for a problem with a given communication graph. The dissertation also briefly discusses completely distributed mapping techniques which will be imperative for machines of the future.published or submitted for publicationnot peer reviewe

Exploring Written Artefacts

This collection, presented to Michael Friedrich in honour of his academic career at of the Centre for the Study of Manuscript Cultures, traces key concepts that scholars associated with the Centre have developed and refined for the systematic study of manuscript cultures. At the same time, the contributions showcase the possibilities of expanding the traditional subject of ‘manuscripts’ to the larger perspective of ‘written artefacts’

Effective field theories for strongly correlated fermions - Insights from the functional renormalization group

'There are very few things that can be proved rigorously in condensed matter physics.' These famous words, brought to us by Nobel laureate Anthony James Leggett in 2003, summarize very well the challenging nature of problems researchers find themselves confronted with when entering the fascinating field of condensed matter physics. The former roots in the inherent many-body character of several quantum mechanical particles with modest to strong interactions between them: their individual properties might be easy to understand, while their collective behavior can be utterly complex. Strongly correlated electron systems, for example, exhibit several captivating phenomena such as superconductivity or spin-charge separation at temperatures far below the energy scale set by their mutual couplings. Moreover, the dimension of the respective Hilbert space grows exponentially, which impedes the exact diagonalization of their Hamiltonians in the thermodynamic limit. For this reason, renormalization group (RG) methods have become one of the most powerful tools of condensed matter research - scales are separated and dealt with iteratively by advancing an RG flow from the microscopic theory into the low-energy regime. In this thesis, we report on two complementary implementations of the functional renormalization group (fRG) for strongly correlated electrons. Functional RG is based on an exact hierarchy of coupled differential equations, which describe the evolution of one-particle irreducible vertices in terms of an infrared cutoff Lambda. To become amenable to numerical solutions, however, this hierarchy needs to be truncated. For sufficiently weak interactions, three-particle and higher-order vertices are irrelevant at the infrared fixed point, justifying their neglect. This one-loop approximation lays the foundation for the N-patch fRG scheme employed within the scope of this work. As an example, we study competing orders of spinless fermions on the triangular lattice, mapping out a rich phase diagram with several charge and pairing instabilities. In the strong-coupling limit, a cutting-edge implementation of the multiloop pseudofermion functional renormalization group (pffRG) for quantum spin systems at zero temperature is presented. Despite the lack of a kinetic term in the microscopic theory, we provide evidence for self-consistency of the method by demonstrating loop convergence of pseudofermion vertices, as well as robustness of susceptibility flows with respect to occupation number fluctuations around half-filling. Finally, an extension of pffRG to Hamiltonians with coupled spin and orbital degrees of freedom is discussed and results for exemplary model studies on strongly correlated electron systems are presented

Earth imaging with microsatellites: An investigation, design, implementation and in-orbit demonstration of electronic imaging systems for earth observation on-board low-cost microsatellites.

This research programme has studied the possibilities and difficulties of using 50 kg microsatellites to perform remote imaging of the Earth. The design constraints of these missions are quite different to those encountered in larger, conventional spacecraft. While the main attractions of microsatellites are low cost and fast response times, they present the following key limitations: Payload mass under 5 kg, Continuous payload power under 5 Watts, peak power up to 15 Watts, Narrow communications bandwidths (9.6 / 38.4 kbps), Attitude control to within 5°, No moving mechanics. The most significant factor is the limited attitude stability. Without sub-degree attitude control, conventional scanning imaging systems cannot preserve scene geometry, and are therefore poorly suited to current microsatellite capabilities. The foremost conclusion of this thesis is that electronic cameras, which capture entire scenes in a single operation, must be used to overcome the effects of the satellite's motion. The potential applications of electronic cameras, including microsatellite remote sensing, have erupted with the recent availability of high sensitivity field-array CCD (charge-coupled device) image sensors. The research programme has established suitable techniques and architectures necessary for CCD sensors, cameras and entire imaging systems to fulfil scientific/commercial remote sensing despite the difficult conditions on microsatellites. The author has refined these theories by designing, building and exploiting in-orbit five generations of electronic cameras. The major objective of meteorological scale imaging was conclusively demonstrated by the Earth imaging camera flown on the UoSAT-5 spacecraft in 1991. Improved cameras have since been carried by the KITSAT-1 (1992) and PoSAT-1 (1993) microsatellites. PoSAT-1 also flies a medium resolution camera (200 metres) which (despite complete success) has highlighted certain limitations of microsatellites for high resolution remote sensing. A reworked, and extensively modularised, design has been developed for the four camera systems deployed on the FASat-Alfa mission (1995). Based on the success of these missions, this thesis presents many recommendations for the design of microsatellite imaging systems. The novelty of this research programme has been the principle of designing practical camera systems to fit on an existing, highly restrictive, satellite platform, rather than conceiving a fictitious small satellite to support a high performance scanning imager. This pragmatic approach has resulted in the first incontestable demonstrations of the feasibility of remote sensing of the Earth from inexpensive microsatellites