Sleep Mode Analysis via Workload Decomposition

The goal of this paper is to establish a general approach for analyzing queueing models with repeated inhomogeneous vacations. The server goes on for a vacation if the inactivity prolongs more than the vacation trigger duration. Once the system enters in vacation mode, it may continue for several consecutive vacations. At the end of a vacation, the server goes on another vacation, possibly with a different probability distribution; if during the previous vacation there have been no arrivals. However the system enters in vacation mode only if the inactivity is persisted beyond defined trigger duration. In order to get an insight on the influence of parameters on the performance, we choose to study a simple M/G/1 queue (Poisson arrivals and general independent service times) which has the advantage of being tractable analytically. The theoretical model is applied to the problem of power saving for mobile devices in which the sleep durations of a device correspond to the vacations of the server. Various system performance metrics such as the frame response time and the economy of energy are derived. A constrained optimization problem is formulated to maximize the economy of energy achieved in power save mode, with constraints as QoS conditions to be met. An illustration of the proposed methods is shown with a WiMAX system scenario to obtain design parameters for better performance. Our analysis allows us not only to optimize the system parameters for a given traffic intensity but also to propose parameters that provide the best performance under worst case conditions

Promoting Bicycle Commuter Safety, Research Report 11-08

We present an overview of the risks associated with cycling to emphasize the need for safety. We focus on the application of frameworks from social psychology to education, one of the 5 Es—engineering, education, enforcement, encouragement, and evaluation. We use the structure of the 5 Es to organize information with particular attention to engineering and education in the literature review. Engineering is essential because the infrastructure is vital to protecting cyclists. Education is emphasized since the central focus of the report is safety

It's Time for Summer: An Analysis of Recent Policy and Funding Opportunities

Recommends ways to improve and expand summer learning programs by better coordinating federal, state and local programs, including ensuring that federal program regulations explicitly allow spending for summer programs and creating funding collaboratives

The Contribution of Rural Tourism to the Sustainable Development of the Rural Areas

There are some elements related to the concept of rural tourism which has nowadays become very important around the world. The rural tourism can revitalize the conventional concepts and views on tourism, and bring in a new dimension to the sustainable development of tourism. It has been realized that tourism can play a major role in many countries economies, especially in developing ones, where it can substantially contribute to the increase of the national income. In this respect, mention should be made that Romania has a lot of resources to develop this tourism branch: villages with well conserved traditions, folklore, wildlife, natural heritage. All these natural elements put in value together with investments in infrastructure have determined an increasing demand for the Romanian rural destinations.sustainable development, rural tourism, sustainability

Workloads and waiting times in single-server systems with multiple customer classes

One of the most fundamental properties that single-server multi-class service systems may possess is the property of work conservation. Under certain restrictions, the work conservation property gives rise to a conservation law for mean waiting times, i.e., a linear relation between the mean waiting times of the various classes of customers. This paper is devoted to single-server multi-class service systems in which work conservation is violated in the sense that the server's activities may be interrupted although work is still present. For a large class of such systems with interruptions, a decomposition of the amount of work into two independent components is obtained; one of these components is the amount of work in the corresponding systemwithout interruptions. The work decomposition gives rise to a (pseudo)conservation law for mean waiting times, just as work conservation did for the system without interruptions

Deregulated Wholesale Electricity Prices in Italy.

In this paper we analyze the time series of daily average prices generated in the Italian electricity market, which started to operate as a Pool in April 2004. The objective is to characterize the high degree of autocorrelation and multiple seasonalities in the electricity prices. We use periodic time series models with GARCH disturbances and leptokurtic distributions and compare their performance with more classical ARMA-GARCH processes. The within-year seasonal variation is modelled using the low frequencies components of physical quantities, which are very regular throughout the sample. Results reveal that much of the variability of the price series is explained by deterministic multiple seasonalities which interact with each other. Periodic AR-GARCH models seem to perform quite well in mimicking the features of the stochastic part of the price process.Electricity auctions, Periodic Time Series, Conditional Heteroskedasticity, Multiple Seasonalities

Flexibilization and precarization of working conditions and labor relations in the perspective of app-based drivers

Purpose – The challenges of the growth of the sharing economy are becoming more and more noticeable and urgent, especially concerning labor relations (e.g. uberization). The purpose of this paper is to understand what app-based drivers think of working conditions and labor relations. Design/methodology/approach – The research was carried out in three stages: bibliographical and documental research, and two empirical research, a quantitative one with the application of a questionnaire in a sample of 54 respondents and another qualitative one using an interview script with ten drivers. For data analysis, the abductive method and the content analysis technique were used. Findings – The results reveal they have an exhausting labor routine, by checking that they work more hours per week than those who have a formal job. They are driven mainly by the extra income and flexibility that digital platforms of the sector of shared private transportation can offer, although the costs intrinsic to the activity often affect their revenues significantly. Research limitations/implications – The number of answers from women was very small, which hinders the analysis of the potential specificities of women app-based drivers. Future studies could focus on this public for a more precise analysis, to bring the discussion on gender to the working context of app-based drivers. Practical implications – The authors’ intention with the research reports was to make them relevant, leading to effective policies concerning working conditions and labor relations in the sharing economy, and to stimulate other surveys to understand the activity of an app-based driver of shared private transportation. Originality/value – The authors’ research and this article contribute to the discussion on new work relationships, motivations and (dis)satisfaction with the activity, from the perspective of app-based drivers