Comparison of forecast estimates of seabed subsidence of the Yuzhno-Kirinskoye field

The geodynamic consequences of the field development process include the subsidence of the earth’s surface. Monitoring of deformations in offshore fields is difficult and it is necessary to evaluate them by various methods. It is important to investigate how much the calculated amplitude of the seabed subsidence is reduced by taking into account changes in the porosity and compressibility of the pore space with a decrease in reservoir pressure. The analysis of changes in the petrophysical parameters of the reservoirs of the Daginsky horizon during the projected development of the Yuzhno-Kirinskoye hydrocarbon field for depletion and a decrease in formation pressure by 10 MPa showed that the porosity decrease will be 0.038 absolute percent, the compressibility of the pore space will decrease by 0,08 10-3 1/MPa. With the help of the Petrel software, changes in the thickness of the productive layer from 80 to 120 cm were obtained, which can be taken as an estimate of the seabed subsidence in the area of the field. The application of the genetic model of the deformable formation by Kuzmin Yu showed that the maximum amplitude of the seabed subsidence to be 101 cm. Comparison of these estimates of the seabed subsidence indicates their proximity. Taking into account the dynamics of tectonophysical and petrophysical characteristics due to the long-term development of hydrocarbon deposits significantly changes the intensity of the deformation state of the rock mass and the earth’s surface above the field.

2D perfusion angiography as quantitative method to evaluate iloprost effect on foot circulation

Summary: Background: Two-dimensional (2D) perfusion angiography is useful for the evaluation of foot perfusion in patients with critical limb-threatening ischemia (CLTI). Iloprost is a synthetic prostacyclin analogue presenting vasodilating properties. Aim of this study was to demonstrate the utility of 2D perfusion angiography as quantitative method to evaluate iloprost effect on foot circulation. Patients and methods: Between January 2020 and June 2020 25 patients with CLTI underwent below-the-knee (BTK) endovascular revascularization, intra-arterial administration of iloprost, and assessment of foot perfusion by 2D perfusion angiography. Iloprost was administered as an intra-arterial bolus of 3 μg over 1–3 minutes immediately after BTK revascularization. The 2D perfusion angiography was performed in a standardized manner with a 5-F catheter placed into the popliteal artery. A wide region of interest (ROI) was identified to assess the foot perfusion. Time–density curves were calculated by the perfusion software. Changes of the overall time-density curves before and after the administration of iloprost were evaluated. Results: Endovascular revascularization was successful in all cases. The mean reduction of systolic pressure value after iloprost administration was 23.1 mmHg. Eight patients (32%) experienced a minor complication (6 cutaneous rush, 2 symptomatic hypotension >40 mmHg). In 20 patients the time-density curves under ROI increased after the intra-arterial administration of iloprost (+31.6%, range from +4.9% to +78.7%). Five patients had no modification or a slight decrease of foot perfusion after iloprost administration (non-responders patients). Conclusions: Patients undergoing intra-arterial administration of iloprost accounted for a not negligible rate of minor complications. 2D perfusion angiography was valuable as quantitative method to evaluate the iloprost effect on foot circulation. This technique could be useful to classify the patients in responders or non-responders to iloprost therapy.

Collaborative Reengineering and Modularization of Software Systems

Software systems evolve over their lifetime. Changing requirements make it inevitable to modify and extend the underlying source code. Understanding software systems embodies a crucial task, which needs to be addressed in an appropriate way to face inevitable challenges while performing software changes. In this thesis, we introduce three complementary approaches to support the evolution and particularly understanding of software systems in different aspects. Our main contributions are (i) an approach named CORAL for enabling collaborative reengineering and modularization of software systems, (ii) a gesture-based, collaborative, and multi-user-featuring Virtual Reality approach named ExplorViz VR for the software city metaphor, and (iii) a database behavior live-visualization approach named RACCOON for database comprehension of software systems. An extensive case study shows that our CORAL approach is capable of supporting reengineering and modularization processes. Furthermore, several evaluations demonstrate the high usability, and efficiency and effectiveness for solving comprehension tasks when using our multi-user VR approach ExplorViz VR.

Predicting the time-to-deliver of software changes

In this thesis we examine the application of survival analysis on time-to-deliver data. Successful prediction of the time necessary to deliver a new feature or fix a reported defect can assist in various phases and aspects of software development. We identify and try to overcome limitations when dealing with time-to-event data. Our proposed methodological framework includes use of survival analysis, utilization of incomplete information that might be available as censored data, and incorporation of random-effects through mixed-effects models for identification of hierarchical/clustered data within our dataset. We explore and experiment with a dataset from a large scale commercial software over a twelve year period of time. We show that we can successfully implement survival analysis, and that incorporation of random-effects provides a considerable advantage, however, incorporation of censored information is not proven to be advantageous in this case.

Predicting the time-to-deliver of software changes

In this thesis we examine the application of survival analysis on time-to-deliver data. Successful prediction of the time necessary to deliver a new feature or fix a reported defect can assist in various phases and aspects of software development. We identify and try to overcome limitations when dealing with time-to-event data. Our proposed methodological framework includes use of survival analysis, utilization of incomplete information that might be available as censored data, and incorporation of random-effects through mixed-effects models for identification of hierarchical/clustered data within our dataset. We explore and experiment with a dataset from a large scale commercial software over a twelve year period of time. We show that we can successfully implement survival analysis, and that incorporation of random-effects provides a considerable advantage, however, incorporation of censored information is not proven to be advantageous in this case.

Improving the Accuracy of Static Source Code Based Software Change Impact Analysis Through Hybrid Techniques: A Review

Change is an inevitable phenomenon of life. This inevitability of change in the real world has made a software change an indispensable characteristic of software systems and a fundamental task of software maintenance and evolution. The continuous evolution process of software systems can greatly affect the systems’ quality and reliability if proper mechanisms to manage them are not adequately provided. Therefore, there is a need for automated techniques to effectively make an assessment of proposed software changes that may arise due to bug fixes, technological advancements, changing user requirements etc., before their implementation. Software Change Impact Analysis (CIA) is an essential activity for comprehending and identifying potential change impacts of software changes that can help prevent the system from entering into an erroneous state. Despite the emergence of different CIA techniques, they are yet to reach an optimal level of accuracy desired by software engineers. Consequently, researchers in recent years have come up with hybrid CIA techniques which are a blend of multiple CIA approaches, as a way of improving the accuracy of change impacts analysis techniques. This study presents these hybrid CIA techniques and how they improve accuracy. They are also compared and areas for further research are identified.

Survey on Software Changes: Reasons and Remedies

Software systems play a key role in most businesses nowadays. Building robust, reliable and scalable software systems require going through a software production cycle (or process). However, it has been noticed that software systems are subjected to changes, whether those amendments are important or not. Those changes to software systems are viewed as a considerable issue in software engineering; they are considered as a burden and cost a lot, especially in cases such as enterprises and large-scale software systems. This study aims to identify the reasons that cause software changes and suggest remedies for those reasons. We survey the opinions of experts such as technical managers, team leaders, and senior developers. We collected 81 responses to our questionnaire, which aimed to establish common software development practices in the local industry. We also conducted 16 semi-structured interviews targeting the most senior experts, in which we directly discussed the reasons and remedies for software changes. Our results highlight the most influential reasons that cause changes to software systems, such as changes to user requirements, requests for new features, software development methodology, solving bugs, refactoring, and weak user experience design. Most importantly, the study solicited solutions that can reduce the need for software changes