A study on performance measures for auto-scaling CPU-intensive containerized applications

Autoscaling of containers can leverage performance measures from the different layers of the computational stack. This paper investigate the problem of selecting the most appropriate performance measure to activate auto-scaling actions aiming at guaranteeing QoS constraints. First, the correlation between absolute and relative usage measures and how a resource allocation decision can be influenced by them is analyzed in different workload scenarios. Absolute and relative measures could assume quite different values. The former account for the actual utilization of resources in the host system, while the latter account for the share that each container has of the resources used. Then, the performance of a variant of Kubernetes’ auto-scaling algorithm, that transparently uses the absolute usage measures to scale-in/out containers, is evaluated through a wide set of experiments. Finally, a detailed analysis of the state-of-the-art is presented

Optimal mobility-aware admission control in content delivery networks

This paper addresses the problem of mobility management in Content Delivery Networks (CDN). We introduce a CDN architecture where admission control is performed at mobility aware access routers. We formulate a Markov Modulated Poisson Decision Process for access control that captures the bursty nature of data and packetized traffic together with the heterogeneity of multimedia services. The optimization of performance parameters, like the blocking probabilities and the overall utilization, is conducted and the structural properties of the optimal solutions are also studied. Heuristics are proposed to encompass the computational difficulties of the optimal solution when several classes of multimedia traffic are considered

A Fiber Optical Sensor For Non-Contact Vibration Measurements

This paper describes an intensity based optical sensor for the evaluation of accelerations from non-contact displacement measurements. Plastic optical fibers are used to collect the reflected light from several points on the vibrating surface, allowing the reconstruction of the vibration distribution. Two compensation techniques to reduce systematic effects due to the target reflectivity are also described and compared: one is based on the spectral analysis of the received optical signal and the other takes advantage of a reference displacement sensor. Experimental results in real conditions during vibration tests have demonstrated the capability to measure sub-micrometer vibration amplitudes up to about 40 kH

Nominal Agreement in L2 Speakers of Italian: Suggestions for a Teaching Plan

This paper addresses the topic of adult acquisition of nominal agreement in Italian, a crucial issue in teaching Italian as Second/Foreign Language. Building on a corpus containing spontaneous and semi-spontaneous production data from two advanced L2-speakers of Italian, I show that nominal agreement can be problematic even in the last stages of the acquisition process. The discussion of the instances of missing agreement in the corpus suggests that these are not due to a missing knowledge of the agreement rules in Italian, but instead on processing and production. In particular, some contexts prove to be more difficult than others: gender agreement (i.e., agreement with feminine nouns) is more difficult than number agreement, and the presence of two or more modifiers that refer to the same noun increases the error rate. Another difficulty is offered by the cases in which an item external to the determiner phrase (DP) has to agree with the subject of the clause. All these issues are tackled from a teacher’s perspective: I highlight how the various contexts could be addressed and considered in the classroom, in order to help the learners to improve their production. Therefore, this paper argues that the best way to tackle this issue is by coupling knowledge of the formal rules of the language and of the acquisitional process with practical application in the context of second/foreign language teaching

Assessment of a Dual-Wavelength Compensation Technique for Displacement Sensors Using Plastic Optical Fibers

The paper analyzes the performance of a dual-wavelength technique devised to compensate power fluctuations in intensity-modulated plastic optical fiber sensors, which were specifically conceived for the measurement of displacements in industrial and civil applications. These sensors retrieve the displacement from the variation of the attenuation along the light path and use two signals at different wavelengths to compensate for the effects of parasitic quantities, such as temperature and strains along the fiber. The theoretical behavior of the compensation technique is presented, and the results of experiments carried out with different combinations of signal wavelengths and plastic fibers are reported. The experimental setup has proved that, by proper choice of the compensation signal wavelength, it is possible to monitor displacements in the range (0 to 10) mm, even for low received power and under severe perturbation conditions, thus significantly improving the long-term stability of the sensor

Innovative Plastic Optical Fiber Sensors

This thesis describes the development of new types of fiber optic sensors for the measurement of mechanical quantities such as displacement, vibration and acceleration. Also, it describes the realization of specific acquisition systems designed to interrogate the developed sensors. Since optical fibers have been historically associated with high speed telecommunication links because of their very large bandwidth and low attenuation, there is a great interest for their employment in sensor applications. Fiber sensors represent a promising solution in many fields since fibers can be used for the measurement of several quantities, not only mechanical as those investigated in this work, but also chemical with the possibility to detect specific chemical or bio-chemical molecules. Among the physical quantities to be detected, the displacement measurement is required in some applications, especially in structural civil and mechanical fields, where it is possible to evaluate the cracks evolution, providing information about the safety of the structure under monitoring in order to detect eventually risky situations. All the developed sensors are able to measure the displacement along one or two axis, that can be employed also during vibration tests especially at high frequencies, and also acceleration sensors to monitor acceleration at low frequencies. The developed sensors are based on plastic optical fibers instead of the traditional glass fibers, which are traditionally employed in optical communications. This change is related to the aim of realizing sensors maintaining the excellent typical characteristics of the fibers, such as electromagnetic immunity, intrinsically fire safety and flexibility of applications, but with costs comparable to those of commercial electromechanical sensors. Indeed, nowadays, the commercial fiber optic sensors are based on glass fibers because they have very good performance. However, they find limited applications due to the high costs of their complex interrogation systems and also for the procedure required to splice the fibers. On the other hand, plastic optical fibers represent a promising alternative because of their geometrical and optical properties that allow employing low-cost non coherent sources such as LED and also simplifying the procedure for the sensor connection and installation. Therefore, the design of the proposed plastic optical fiber displacement sensors is described with the sensor practical arrangement and the realized prototypes. An acquisition system has been designed and realized to characterize the sensors and the characterization results are also provided. Moreover, the development and the characterization of a plastic optical fiber sensor able to measure the displacement in two directions have been described. The main drawback of the developed sensors are stability issues and for this reason laboratory and in situ-tests have been carried out in order to verify the sensor performance over the time. I The results obtained with the stability tests have highlighted the necessity to develop displacement sensors with increased stability. To this aim, a compensation technique based on two different wavelengths has been developed. The same working principle of the developed displacement sensor has been exploited to realize a fiber vibrometer to be employed during the vibration monitoring for measuring without contact the vibrations of the device under test. The sensor development, a suitable calibration procedure developed to overcome the problem of real targets with a non uniform reflectivity, and the experimental tests have been described. Furthermore, the preliminary results concerning the feasibility study of a plastic optical fiber accelerometer are reporte

Multilabel Classification with R Package mlr

We implemented several multilabel classification algorithms in the machine learning package mlr. The implemented methods are binary relevance, classifier chains, nested stacking, dependent binary relevance and stacking, which can be used with any base learner that is accessible in mlr. Moreover, there is access to the multilabel classification versions of randomForestSRC and rFerns. All these methods can be easily compared by different implemented multilabel performance measures and resampling methods in the standardized mlr framework. In a benchmark experiment with several multilabel datasets, the performance of the different methods is evaluated.Comment: 18 pages, 2 figures, to be published in R Journal; reference correcte

A syntactic analysis of the subject clitic a in the Friulian variety of Campone

This article presents a syntactic analysis of the third person subject clitic a in Camponese, a heretofore unstudied Friulian variety. Following Poletto's (2000) map of subject clitics, we argue that it bears [+third person] features, and is, in fact, the spell-out of the functional head Subj°, located in the highest projection of TP (following Rizzi & Shlonsky 2007). In the first part of the article, we offer a detailed description of the distribution and syntactic properties of the subject clitic a, identifying its position in relation to the other elements that occur in the CP and TP. In the second part we discuss two proposals put forward to account for split clitics like a-l in the related variety of Forni di Sotto, where a and l are held to be part of a single clitic al (Manzini & Savoia 2009, Calabrese & Pescarini 2014). We show that such an account is incompatible with the case of Campone, where the clitics a and l are clearly separate: l is a [uφ]-clitic (Roberts 2010) and is located lower in the TP than the clitic a. We conclude with an analysis, which proposes the integration of Poletto's (2000) typology with a fifth type, corresponding to the clitic a of Campone

Microvariation in the Distribution of Resumptive Pronouns in the Left Dislocation Construction in Two Tyrolean Dialects of Northern Italy

In this paper we document a so-far neglected case of microvariation involving resumptive pronouns in the left-dislocation construction in Meranese, spoken in South Tyrol, and Mòcheno, spoken in the Fersina valley (Trentino). While in standard German resumptive elements in this construction belong to the class of D-pronouns, the two Tyrolean dialects considered in the paper exhibit, as resumptive pronouns, both (i) D-pronouns and (ii) pronominal usages of the distal demonstrative formed by the definite article (D) and sèll corresponding to ‘that one’. We show that in both languages D+sèll forms overlap with German D-pronouns in most contexts, whereas D-pronouns only superficially, but not functionally, correspond to German D-pronouns, and have undergone a weakening process. While the weakening process is in nuce in Meranese, it seems to be nearly completed in Mòcheno, where D-pronouns appear to have acquired a status close to that of subject clitics of Northern Italian varieties