On Refining Design Patterns for Smart Contracts: A use case on water management

The need for a Blockchain Oriented Software Engineering (BOSE) has been recognized in several research papers. Design Patterns are considered among the main and compelling areas to be developed in BOSE. Anyway, design patterns need to be enhanced with some additional fields to better support the specific needs of Blockchain development. In this paper, we discuss the use of Solidity design patterns applied to a water management use case and we introduce specific fields in their description, aiming at offering to Blockchain developers more support in the critical decisions to build efficient decentralized applications

Change impact analysis: A systematic mapping study

Change Impact Analysis (CIA) is the process of exploring the tentative effects of a change in other parts of a system. CIA is considered beneficial in practice, since it reduces cost of maintenance and the risk of software development failures. In this paper, we present a systematic mapping study that covers a plethora of CIA methods (by exploring 111 papers), putting special emphasis on how the CIA phenomenon can be quantified: to be efficiently managed. The results of our study suggest that: (a) the practical benefits of CIA cover any type of maintenance request (e.g., feature additions, bug fixing) and can help in reducing relevant cost; (b) CIA quantification relies on four parameters (instability, amount of change, change proneness, and changeability), whose assessment is supported by various metrics and predictors; and (c) in this vast research field, there are still some viewpoints that remain unexplored (e.g., the negative consequences of highly change prone artifacts), whereas others are over-researched (e.g., quantification of instability based on metrics). Based on our results, we provide: (a) useful information for practitioners—i.e., the expected benefits of CIA, and a list of CIA-related metrics, emphasizing on the provision of a detailed interpretation of their relation to CIA; and (b) interesting future research directions—i.e., over- and under-researched sub-fields of CIA. © 2020 Elsevier Inc

Regulated and unregulated emissions of a euro 4 suv operated with diesel and soy-based biodiesel blends

In this study, regulated, unregulated exhaust emissions and fuel consumption with ultra low sulphur diesel and soy-based biodiesel blends at proportions of 10 and 30% v/v have been investigated. A Euro 4 compliant SUV, equipped with a 2.2 litre common-rail diesel engine and an oxidation catalyst was tested on a chassis dynamometer with constant volume sampling (CVS) technique. Emission and fuel consumption measurements were performed over the New European Driving Cycle (NEDC) and the non-legislated Artemis driving cycles which simulate urban, rural, and highway driving conditions in Europe. The regulated pollutants were characterized by determined NOx, PM, CO, and HC. CO2 was also quantified in the exhaust. Overall, 16 PAHs, 4 nitro-PAHs, 6 oxy-PAHs, 13 carbonyl compounds and particulate alkanes ranged from C13 to C35 were determined in the exhaust. The experimental results showed that the addition of biodiesel decreased the emissions of PM, CO and HC and increased NOx emissions during real-world driving. CO2 emissions and fuel consumption followed similar patterns and increased. Carbonyl compounds were increased for all fuel/cycle combinations. PAH emissions were found to decrease with biodiesel, with some exemptions in certain compounds. An increase was observed on the straight- chain alkanes composition with biodiesel over all driving cycles. © 2009 SAE International

Effects of low concentration biodiesel blends application on modern passenger cars. Part 3: Impact on PAH, nitro-PAH, and oxy-PAH emissions

This study explores the impact of five different types of methyl esters on polycyclic aromatic hydrocarbon (PAH), nitrated-PAH and oxygenated PAH emissions. The measurements were conducted on a chassis dynamometer, according to the European regulation. Each of the five different biodiesels was blended with EN590 diesel at a proportion of 10-90% v/v (10% biodiesel concentration). The vehicle was a Euro 3 compliant common-rail diesel passenger car. Emission measurements were performed over the NEDC and compared with those of the real traffic-based Artemis driving cycles. The experimental results showed that the addition of biodiesel led to some important increases in low molecular-weight PAHs (phenanthrene and anthracene) and to both increases and reductions in large PAHs which are characterised by their carcinogenic and mutagenic properties. Nitro-PAHs were found to reduce with biodiesel whereas oxy-PAH emissions presented important increases with the biodiesel blends. The impact of biodiesel source material was particularly clear on the formation of PAH compounds. It was found that most PAH emissions decreased as the average load and speed of the driving cycle increased. Cold-start conditions negatively influenced the formation of most PAH compounds. A similar trend was observed with particulate alkane emissions. © 2009 Elsevier Ltd. All rights reserved

Copper complexation in wet precipitation: Impact of different ligand sources

Cu complexation in wet precipitation samples was measured by the method of differential pulse anodic stripping voltammetry (DPASV), which presumed the existence of 1:1 Cu ion-ligand complexes. The wet precipitation samples were collected throughout the rainy period (September 2011-May 2012) from four sampling stations of central and southern Greece, two of which were located in urban coastal areas of its mainland (Athens, n=24; Elefsina, n=11) and the other two on the island of Crete (Heraklio, n=26; Ligortynos, n=12), comprising different features concerning population density, urban/rural/industrial character and influence from the sea. Total Cu (TCu), total organic and inorganic carbon (TOC, IC), pH, conductivity, several inorganic macro-constituents (Cl-, Br-, NO3-, SO42-, Na+, K+, Ca2+, Mg2+), n-alkanes and polycyclic aromatic hydrocarbons (PAHs) were determined for better characterization of the predominant sources and influences.Significant complexation of Cu ions was determined in almost all wet precipitation samples examined, with the apparent complexing capacity of Cu ions in unfiltered samples ranging between 0.07 and 1.9μM and apparent stability constants (logKapp) in the range 6.5-9.6, which corresponds to values comparable to those deriving from a limited number of studies having a common 'detection window'. The percentage in the mass of TOC complexed with copper was up to 4%.Among ligands, sources of terrestrial origin appear to be of particular importance. In terrestrial sources, vegetation and anthropogenic emissions seem to have a prominent impact. © 2013 Elsevier Ltd

On the Temporality of Introducing Code Technical Debt

Code Technical Debt (TD) is intentionally or unintentionally created when developers introduce inefficiencies in the codebase. This can be attributed to various reasons such as heavy work-load, tight delivery schedule, unawareness of good practices, etc. To shed light into the context that leads to technical debt accumulation, in this paper we investigate: (a) the temporality of code technical debt introduction in new methods, i.e., whether the introduction of technical debt is stable across the lifespan of the project, or if its evolution presents spikes; and (b) the relation of technical debt introduction and the development team’s workload in a given period. To answer these questions, we perform a case study on twenty-seven Apache projects, and inspect the number of Technical Debt Items introduced in 6-month sliding temporal windows. The results of the study suggest that: (a) overall, the number of Technical Debt Items introduced through new code is a stable metric, although it presents some spikes; and (b) the number of commits performed is not strongly correlated to the number of introduced Technical Debt Items