Fleet management in free-floating bike sharing systems using predictive modelling and explorative tools

For redistribution and operating bikes in a free-floating systems, two measures are of highest priority. First, the information about the expected number of rentals on a day is an important measure for service providers for management and service of their fleet. The estimation of the expected number of bookings is carried out with a simple model and a more complex model based on meterological information, as the number of loans depends strongly on the current and forecasted weather. Secondly, the knowledge of a service level violation in future on a fine spatial resolution is important for redistribution of bikes. With this information, the service provider can set reward zones where service level violations will occur in the near future. To forecast a service level violation on a fine geographical resolution the current distribution of bikes as well as the time and space information of past rentals has to be taken into account. A Markov Chain Model is formulated to integrate this information. We develop a management tool that describes in an explorative way important information about past, present and predicted future counts on rentals in time and space. It integrates all estimation procedures. The management tool is running in the browser and continuously updates the information and predictions since the bike distribution over the observed area is in continous flow as well as new data are generated continuously

Reputation in multi agent systems and the incentives to provide feedback

The emergence of the Internet leads to a vast increase in the number of interactions between parties that are completely alien to each other. In general, such transactions are likely to be subject to fraud and cheating. If such systems use computerized rational agents to negotiate and execute transactions, mechanisms that lead to favorable outcomes for all parties instead of giving rise to defective behavior are necessary to make the system work: trust and reputation mechanisms. This paper examines different incentive mechanisms helping these trust and reputation mechanisms in eliciting users to report own experiences honestly. --Trust,Reputation

Cracking the Network Code: Four Principles for Grantmakers

As grantmakers and nonprofits are looking for ways to collaborate more effectively, many are experimenting working with and through networks to achieve greater impact. Because networks are by definition loosely controlled and emergent, understanding how to effectively support them feels like a mystery to many grantmakers.GEO's newest publication sets out to crack the code behind the network mystique. In fact, there is a method to working more efficiently and effectively through networks, and a critical first step for grantmakers is adopting a network mindset, which may require dramatic shifts in attitude and behavior for some. "Cracking the Network Code" outlines four principles that comprise the network mindset, illustrates the principles with a range of examples of networks that have achieved real results, and offers practical questions and recommendations to help grantmakers achieve the benefits and avoid common pitfalls of working through networks

A particle filter to reconstruct a free-surface flow from a depth camera

We investigate the combined use of a Kinect depth sensor and of a stochastic data assimilation method to recover free-surface flows. More specifically, we use a Weighted ensemble Kalman filter method to reconstruct the complete state of free-surface flows from a sequence of depth images only. This particle filter accounts for model and observations errors. This data assimilation scheme is enhanced with the use of two observations instead of one classically. We evaluate the developed approach on two numerical test cases: a collapse of a water column as a toy-example and a flow in an suddenly expanding flume as a more realistic flow. The robustness of the method to depth data errors and also to initial and inflow conditions is considered. We illustrate the interest of using two observations instead of one observation into the correction step, especially for unknown inflow boundary conditions. Then, the performance of the Kinect sensor to capture temporal sequences of depth observations is investigated. Finally, the efficiency of the algorithm is qualified for a wave in a real rectangular flat bottom tank. It is shown that for basic initial conditions, the particle filter rapidly and remarkably reconstructs velocity and height of the free surface flow based on noisy measurements of the elevation alone

Burying the palaces? Ideologies in the Shaft Grave period

The ‘Shaft Grave Phenomenon’ is often seen as a straightforward development caused by increased access to precious (‘prestige’) items. It shall be argued here that it rather mirrors a gradual transformation of the self-identity of the mainland élites. The Shaft Grave chiefs strongly took over symbols from Crete, where the palatial élite had a strong religious connotation. This points to the conclusion that the mainland élite tried to establish a more sophisticated system of religious control, unlike the individual and personal cult visible in the MH burials. They realized the potential institutionalized religious authority had as a means of domination, connected with complex and standardised systems of representation, centralization and administration of cult, and tried to introduce this idea to the mainland. However, the symbols had to be modified and translated into a language mainland people would understand, and placed in contexts traditionally used as arenas of social display. These contexts were different from the ones the symbols originally were associated with, since on the MH mainland the grave (as opposed to the Minoan palace) was the place where transcendental ideas were articulated through material actions and expressions

Modélisation du prétraitement des textes

Dans cet article, nous définissons un modèle pour l'étape de prétraitement des textes dans le cadre de la fouille de textes et plus généralement de l'extraction d'informations à partir de textes. Cet article ne contient pas les détails de l'implémentation. L'objectif est d'obtenir un modèle générique de normalisation des textes bruts. La motivation de cet article est de généraliser les travaux assez confidentiels et spécialisés qui existent pour cette étape de prétraitement. Cette étape est pourtant incontournable et d'elle dépend grandement la qualité des analyses obtenues à toutes les étapes ultérieures

A Low-Distortion Map Between Triangle and Square

We introduce a low-distortion map between triangle and square. This mapping yields an area-preserving parameterization that can be used for sampling random points with a uniform density in arbitrary triangles. This parameterization presents two advantages compared to the square-root param-eterization typically used for triangle sampling. First, it has lower distortions and better preserves the blue-noise properties of the input samples. Second, its computation relies only on arithmetic operations (+, *), which makes it faster to evaluate

La solitude dans le cinéma de Carlos Sorín

Cet article se propose d'étudier le thème de la solitude dans trois films du cinéaste argentin Carlos Sorín, solitude brisée par l'abolition d'un temps de l'urgence, urgence inconnue des êtres qui peuplent les immenses espaces patagoniens. La solitude est brisée aussi par la solidarité des êtres (humains et animaux), filmés avec tendresse et humour, et par la poursuite sereine des rêves intime