The safety of higher order demand propagation

Higher Order Demand Propagation as proposed in [Pa98] provides a non-standard denotational semantics for a realistic functional language. This semantics can be used to deduce generalised strictness information for higher order polymorphic functions. This report provides the formal proof for the correctness of this strictness information with respect to the non-strict standard semantics

Does intra-firm bargaining matter for business cycle dynamics?

We analyse the implications of intra-firm bargaining for business cycle dynamics in models with large firms and search frictions. Intra-firm bargaining implies a feedback effect from the marginal revenue product to wage setting which leads firms to over-hire in order to reduce workers' bargaining position within the firm. The key to this effect are decreasing returns and/or downward-sloping demand. We show that equilibrium wages and employment are higher in steady state compared to a bargaining framework in which firms neglect this feedback. However, the effects of intra-firm bargaining on adjustment dynamics, volatility and comovement are negligible. --Strategic wage setting,search and matching frictions,business cycle propagation

Caracterización espacial de canal mediante sistemas multiantena con OFDM

A key point for satisfying the higher data rates that the new wireless communication services demand is to explore and apply several diversity schemes simultaneously. The frequency diversity given by OFDM (Orthogonal Frequency Division Multiplexing) systems increase information of received signals, i.e. Direction-of-arrival (DoA) profiles. In this paper, a proper spatial channel characterization in terms of DoA profiles is conducted using MUSIC algorithm. A MIMO-OFDM testbed is been designed to carried out a measurement campaign in several propagation environments. In order to facilitate the repeatability of taking measurements in the experimental campaign, an automatic positioning system is presented. Several virtual array geometries are studied in terms of DoA resolutio

Using the general link transmission model in a dynamic traffic assignment to simulate congestion on urban networks

This article presents two new models of Dynamic User Equilibrium that are particularly suited for ITS applications, where the evolution of vehicle flows and travel times must be simulated on large road networks, possibly in real-time. The key feature of the proposed models is the detail representation of the main congestion phenomena occurring at nodes of urban networks, such as vehicle queues and their spillback, as well as flow conflicts in mergins and diversions. Compared to the simple word of static assignment, where only the congestion along the arc is typically reproduced through a separable relation between vehicle flow and travel time, this type of DTA models are much more complex, as the above relation becomes non-separable, both in time and space. Traffic simulation is here attained through a macroscopic flow model, that extends the theory of kinematic waves to urban networks and non-linear fundamental diagrams: the General Link Transmission Model. The sub-models of the GLTM, namely the Node Intersection Model, the Forward Propagation Model of vehicles and the Backward Propagation Model of spaces, can be combined in two different ways to produce arc travel times starting from turn flows. The first approach is to consider short time intervals of a few seconds and process all nodes for each temporal layer in chronological order. The second approach allows to consider long time intervals of a few minutes and for each sub-model requires to process the whole temporal profile of involved variables. The two resulting DTA models are here analyzed and compared with the aim of identifying their possible use cases. A rigorous mathematical formulation is out of the scope of this paper, as well as a detailed explanation of the solution algorithm. The dynamic equilibrium is anyhow sought through a new method based on Gradient Projection, which is capable to solve both proposed models with any desired precision in a reasonable number of iterations. Its fast convergence is essential to show that the two proposed models for network congestion actually converge at equilibrium to nearly identical solutions in terms of arc flows and travel times, despite their two diametrical approaches wrt the dynamic nature of the problem, as shown in the numerical tests presented here

Cloud/fog computing resource management and pricing for blockchain networks

The mining process in blockchain requires solving a proof-of-work puzzle, which is resource expensive to implement in mobile devices due to the high computing power and energy needed. In this paper, we, for the first time, consider edge computing as an enabler for mobile blockchain. In particular, we study edge computing resource management and pricing to support mobile blockchain applications in which the mining process of miners can be offloaded to an edge computing service provider. We formulate a two-stage Stackelberg game to jointly maximize the profit of the edge computing service provider and the individual utilities of the miners. In the first stage, the service provider sets the price of edge computing nodes. In the second stage, the miners decide on the service demand to purchase based on the observed prices. We apply the backward induction to analyze the sub-game perfect equilibrium in each stage for both uniform and discriminatory pricing schemes. For the uniform pricing where the same price is applied to all miners, the existence and uniqueness of Stackelberg equilibrium are validated by identifying the best response strategies of the miners. For the discriminatory pricing where the different prices are applied to different miners, the Stackelberg equilibrium is proved to exist and be unique by capitalizing on the Variational Inequality theory. Further, the real experimental results are employed to justify our proposed model.Comment: 16 pages, double-column version, accepted by IEEE Internet of Things Journa

DVB-RCS return link radio resource management for broadband satellite systems using fade mitigation techniques at ka band

Current Broadband Satellite systems supporting DVB-RCS at Ku band have static physical layer in order not to complicate their implementation. However at Ka band frequencies and above an adaptive physical layer wherein the physical layer parameters are dynamically modified on a per user basis is necessary to counteract atmospheric attenuation. Satellite Radio Resource Management (RRM) at the Medium Access Control (MAC) layer has become an important issue given the emphasis placed on Quality of Service (QoS) provided to the Users. The work presented here tackles the problem of Satellite RRM for Broadband Satellite systems using DVB-RCS where a fully adaptive physical layer is envisaged at Ka band frequencies. The impact of adaptive physical layer and user traffic conditions on the MAC layer functions is analyzed and an algorithm is proposed for the RRM process. Various physical layer issues associated with the resource management problem are also analyzed

A search-theoretic monetary business cycle model with capital formation

Search-theory has become the main paradigm for the micro-foundation of money. But no comprehensive business cycle analysis has been undertaken yet with a search-based monetary model. We extend the model with divisible goods and divisible money of Shi (JET, 1998) to allow for capital formation, analyze the monetary propagation mechanism and contrast the model's implications with US business cycle stylized facts. With empirically plausible adjustment costs the model features a persistent propagation of monetary shocks and is able to replicate fairly well the volatility and cross-correlation with output of key US time series, including sales and inventory investment. We find that monetary policy shocks are unlikely to be an important source of business cycle fluctuations but discover another dimension where money matters: the very frictions that make money essential shape also the responses of variables to real shocks