API Failures in Openstack Cloud Environments

Des histoires sur les pannes de service dans les environnements infonuagiques ont fait les manchettes récemment. Dans de nombreux cas, la fiabilité des interfaces de programmation d’applications (API) des infrastructures infonuagiques étaient en défaut. Par conséquent, la compréhension des facteurs qui influent sur la fiabilité de ces APIs est importante pour améliorer la disponibilité des services infonuagiques. Dans cette thèse, nous étudions les défaillances des APIs de la plateforme OpenStack ; qui est la plate-forme infonuagique à code source ouvert la plus populaire à ce jour. Nous examinons les bogues de 25 modules contenus dans les 5 APIs les plus importantes d’OpenStack, afin de comprendre les défaillances des APIs infonuagiques et leurs caractéristiques. Nos résultats montrent que dans OpenStack, un tiers de tous les changements au code des APIs a pour objectif la correction de fautes ; 7% de ces changements modifiants l’interface des APIs concernés (induisant un risque de défaillances des clients de ces APIs). Grâce à l’analyse qualitative d’un échantillon de 230 défaillances d’APIs et de 71 défaillances d’APIs ayant eu une incidence sur des applications tierces, nous avons constaté que la majorité des défaillances d’APIs sont attribuables à de petites erreurs de programmation. Nous avons également observé que les erreurs de programmation et les erreurs de configuration sont les principales causes des défaillances ayant une incidence sur des applications tierces. Nous avons mené un sondage auprès de 38 développeurs d’OpenStack et d’applications tierces, dans lequel les participants étaient invités à se prononcer sur la propagation de défaillances d’APIs à des applications tierces. Parmi les principales raisons fournies par les développeurs pour expliquer l’apparition et la propagation des défaillances d’APIs dans les écosystèmes infonuagiques figurent : les petites erreurs de programmation, les erreurs de configuration, une faible couverture de test, des examens de code peu fréquents, et une fréquence de production de nouvelles versions trop élevé. Nous avons exploré la possibilité d’utiliser des contrôleurs de style de code, pour détecter les petites erreurs de programmation et les erreurs de configuration tôt dans le processus de développement, mais avons constaté que dans la plupart des cas, ces outils sont incapables de localiser ces types d’erreurs. Heureusement, le sujet des rapports de bogues, les messages contenues dans ces rapports, les traces d’exécutions, et les délais de réponses entre les commentaires contenues dans les rapports de bogues se sont avérés très utiles pour la localisation des fautes conduisant aux défaillances d’APIs.----------ABSTRACT: Stories about service outages in cloud environments have been making the headlines recently. In many cases, the reliability of cloud infrastructure Application Programming Interfaces (APIs) were at fault. Hence, understanding the factors affecting the reliability of these APIs is important to improve the availability of cloud services. In this thesis, we investigate API failures in OpenStack ; the most popular open source cloud platform to date. We mine the bugs of 25 modules within the 5 most important OpenStack APIs to understand API failures and their characteristics. Our results show that in OpenStack, one third of all API-related changes are due to fixing failures, with 7% of all fixes even changing the API interface, potentially breaking clients. Through a qualitative analysis of 230 sampled API failures, and 71 API failures that impacted third parties applications, we observed that the majority of API-related failures are due to small programming faults. We also observed that small programming faults and configuration faults are the most frequent causes of failures that propagate to third parties applications. We conducted a survey with 38 OpenStack and third party developers, in which participants were asked about the causes of API failures that propagate to third party applications. These developers reported that small programming faults, configuration faults, low testing coverage, infrequent code reviews, and a rapid release frequency are the main reasons behind the appearance and propagation of API failures. We explored the possibility of using code style checkers to detect small programming and configuration faults early on, but found that in the majority of cases, they cannot be localized using the tools. Fortunately, the subject, message and stack trace as well as the reply lag between comments included in the failures’ bug reports provide a good indication of the cause of the failure

Effect of foliar application of salicylic acid and mycorrhiza on quantitative and qualitative traits of maize

Abstract An experiment was performed to investigate the effect of mycorrhizal symbiosis and foliar application of salicylic acid on quantitative and qualitative traits of maize during 2018 and 2019 in the research farm of Islamic Azad University, Chalous Branch. Split plot in a randomized complete block design with three replications was used. Experimental factors included mycorrhiza species of (G. mosseae), (G. geosporum) and (G. intraradices) at two levels (no consumption and consumption of mycorrhiza) and salicylic acid at two levels (no consumption and consumption of 1 mμ of salicylic acid). Results of interaction effects of mycorrhiza and salicylic acid on the measured traits revealed that the maximum 1000-grain weight, grain yield, biological yield, phosphorus, potassium, nitrogen percentage and yield of maize grain protein were observed in G. mosseae treatment under foliar application of salicylic acid. Foliar application of salicylic acid increases the root length and provides the necessary conditions for increasing water and nutrient uptake alongwith increase in photosynthesis and thus allocates more photosynthetic substance for development of reproductive organs. Hence, it increases maize grain weight and accordingly grain yield. In general, the results revealed that mycorrhiza and foliar application of salicylic acid increase growth indicators, yield and yield components. It also improved the quality traits of the maize plant. Based on results, the interaction effect of G. mosseae treatment and foliar application of salicylic acid yielded better results than other treatments. Mycorrhiza increases the number of grain in the ear, the number of rows in the ear, increases the plant's ability to absorb phosphorus, and the increase of mycorrhiza along with salicylic acid shows the maximum grain yield in maize. Finally, it can be concluded that the use of mycorrhiza and salicylic acid can be effective in increasing grain in the plant

Numerical Approximation of Internal Temperature in the Cylinder of an IC Engine

In this study, mollification and marching methods are used to solve an inverse problem in combustion engines. With the benefit of 2D mollification, we first propose an algorithm, and then prove some theorems, which ensure us the proposed method in stable and reliable, and then some numerical experiment has been done to show the efficiency of the method

AN X-RAY IMAGING AND NUMERICAL SIMULATION MODELLING OF DIFFERENT IMMISCIBLE WATER ALTERNATING GAS INJECTION SCHEMES FOR OPTIMUM DISPLACEMENT EFFICIENCY

Water Alternating Gas (WAG) injection is a well-known Enhanced Oil Recovery process to improve sweep and displacement efficiency by gas trapping and controlling the mobility of gas. The main aim of the WAG injection is to maximize the three�phase flow region in the reservoir and minimize non-swept areas. The physics of the displacement processes during WAG injection is, however, complex due to three�phase flow in porous media. In this research, to better understand the active mechanisms of immiscible WAG (I-WAG), a series of visual experiments has been conducted on a 2-D sand pack using an X-Ray image technique with an industrial type of CT-Scan-high resolution�machine. The sand-pack is designed to simulate different schemes of I-WAG with considering the effects of viscous, gravity, and capillary forces in different injection orientations (horizontal and tilted) under ambient and elevated pressure and temperature conditions. The experiments are conducted in up-dip and down-dip orientations for injection. 2-D dynamic injection front profiles are captured that help to understand the swept area, three phase flow region, and mechanisms of I-WAG under the different schemes were studied. Simulation studies are also conducted based on the physical parameters of the sand-pack to simulate the experiments and to be able to run more sensitivity analysis. The trained simulation parameters were validated against the experimental results guide the field simulation of the same process

LABORATORY INVESTIGATION AND SIMULATION MODELING OF DIFFERENT I-WAG SCHEMES TOWARDS OPTIMUM DISPLACEMENT EFFICIENCY

Water alternating gas (WAG) injection is a well-known Enhance Oil Recovery process to improve sweep and displacement efliciency by gas trapping and controlling the mobility of gas. The main aim of the WAG injection is to maximize the three�phase flow region in the reservoir and minimize non-swept areas. The physics of the displacement processes during WAG injection is, however, complex due to three�phase flow in porous media. In this research, to better understand the active mechanisms of immiscible WAG (I-WAG), a series of visual experiments have been conducted on a 20 sandpack by using an X-Ray image technique with an industrial type of CT-Scan-high resolution�machine. The sand-pack is designed to simulate different schemes of 1-WAG with considering the effects of viscous, gravity, and capillary forces in different injection orientations (horizontal and tilted) at ambient and elevated pressure and temperature conditions. The experiments are conducted in up dip and down dip orientations for injection. 20 dynamic injection front profiles are captured that help to understand the swept area, three phase flow region, and mechanisms of 1-WAG under the different schemes were studied. Simulation studies are also conducted based on the physical parameters of the sand-pack to simulate the experiments and to be able to run more sensitivity analysis. The trained simulation parameters validated against the experimental results guide the field simulation of the same process. The efficiency of three different I-WAG injection schemes towards the improvement of recovery factor are investigated by conducting numerical simulation studies on one homogeneous model and one highly heterogeneous real field sector models. The studied first scheme (Scheme I) is up dip gas injection and down dip water injection and the second scheme (Scheme II) is the down dip gas injection and up dip water injection

AN X-RAY IMAGING AND NUMERICAL SIMULATION MODELLING OF DIFFERENT IMMISCIBLE WATER ALTERNATING GAS INJECTION SCHEMES FOR OPTIMUM DISPLACEMENT EFFICIENCY

Water Alternating Gas (WAG) injection is a well-known Enhanced Oil Recovery process to improve sweep and displacement efficiency by gas trapping and controlling the mobility of gas. The main aim of the WAG injection is to maximize the three�phase flow region in the reservoir and minimize non-swept areas. The physics of the displacement processes during WAG injection is, however, complex due to three�phase flow in porous media. In this research, to better understand the active mechanisms of immiscible WAG (I-WAG), a series of visual experiments has been conducted on a 2-D sand pack using an X-Ray image technique with an industrial type of CT-Scan-high resolution�machine. The sand-pack is designed to simulate different schemes of I-WAG with considering the effects of viscous, gravity, and capillary forces in different injection orientations (horizontal and tilted) under ambient and elevated pressure and temperature conditions. The experiments are conducted in up-dip and down-dip orientations for injection. 2-D dynamic injection front profiles are captured that help to understand the swept area, three phase flow region, and mechanisms of I-WAG under the different schemes were studied. Simulation studies are also conducted based on the physical parameters of the sand-pack to simulate the experiments and to be able to run more sensitivity analysis. The trained simulation parameters were validated against the experimental results guide the field simulation of the same process

LABORATORY INVESTIGATION AND SIMULATION MODELING OF DIFFERENT I-WAG SCHEMES TOWARDS OPTIMUM DISPLACEMENT EFFICIENCY

Water alternating gas (WAG) injection is a well-known Enhance Oil Recovery process to improve sweep and displacement efliciency by gas trapping and controlling the mobility of gas. The main aim of the WAG injection is to maximize the three�phase flow region in the reservoir and minimize non-swept areas. The physics of the displacement processes during WAG injection is, however, complex due to three�phase flow in porous media. In this research, to better understand the active mechanisms of immiscible WAG (I-WAG), a series of visual experiments have been conducted on a 20 sandpack by using an X-Ray image technique with an industrial type of CT-Scan-high resolution�machine. The sand-pack is designed to simulate different schemes of 1-WAG with considering the effects of viscous, gravity, and capillary forces in different injection orientations (horizontal and tilted) at ambient and elevated pressure and temperature conditions. The experiments are conducted in up dip and down dip orientations for injection. 20 dynamic injection front profiles are captured that help to understand the swept area, three phase flow region, and mechanisms of 1-WAG under the different schemes were studied. Simulation studies are also conducted based on the physical parameters of the sand-pack to simulate the experiments and to be able to run more sensitivity analysis. The trained simulation parameters validated against the experimental results guide the field simulation of the same process. The efficiency of three different I-WAG injection schemes towards the improvement of recovery factor are investigated by conducting numerical simulation studies on one homogeneous model and one highly heterogeneous real field sector models. The studied first scheme (Scheme I) is up dip gas injection and down dip water injection and the second scheme (Scheme II) is the down dip gas injection and up dip water injection

Incentives in project contracts and their effects on Product Uncertainty

Industries across world use different methods to secure the quality of the contract deliverables. These deliverables are carefully defined in an agreement between project owner and agent (buyer and seller) however, there are several reasons that the quality of the outcome does not fulfill the desired pre-agreed quality. In aerospace as well as power & energy industries, the delivered products (outcome of the contracts) should endure a long lifespan. Although guarantee and warrantees are being used in contracts to secure the quality of the outcome for a short period of time after delivery, in several cases, the quality of the delivered product fails right after guarantee expiration date. Therefore, guarantee and warrantee are not considered to be a preventive means while the requirement for such preventive tool is undeniable. This case study gathers data from aerospace as well as power and energy industries on how these two industries shape up their agreements and what sort of incentives they use and if these applied incentives have assisted them to reach the target. These data will be analyzed in comparison to similar conducted research in this field