Analysis and efficient simulation of queueing models of telecommunications systems

In modern packet-switched telecommunication systems, information (such as email, sound, pictures) is transported in the form of small packets (or cells) of data through a network of links and routers. The Quality of Service provided by such a network can suffer from phenomena such as loss of packets (due to buffer overflow) and excessive delays. These aspects of the system are adequately described by queueing models, so the study of such models is of great relevance for designing systems such that they provide the required QoS. This thesis contributes methods for the efficient estimation of several loss probabilities in various queueing models of communications systems. The focus is on rare-event simulation using importance sampling, but some analytical, asymptotic and numerical results are also provided

The Petrov type of the five-dimensional Myers-Perry metric

We point out that the Myers-Perry metric in five dimensions is algebraically special. It has Petrov type \underline{22}, which is the Petrov type of the five-dimensional Schwarzschild metric.Comment: 4 pages, 1 figur

Analysis of State-Independent Importance-Sampling Measures for the Two-Node Tandem Queue

We investigate the simulation of overflow of the total population of a Markovian two-node tandem queue model during a busy cycle, using importance sampling with a state-independent change of measure. We show that the only such change of measure that may possibly result in asymptotically efficient simulation for large overflow levels is exchanging the arrival rate with the smallest service rate. For this change of measure, we classify the model's parameter space into regions of asymptotic efficiency, exponential growth of the relative error, and infinite variance, using both analytical and numerical techniques

The impact of EU price rules: Interchange fee regulation in retail payments. CEPS-ECRI Working Paper 4 February 2020

Debit and credit cards have gradually increased in importance as instruments for retail payments. This has prompted anti-trust authorities at both national and European levels to investigate and limit the interchange fee-based revenue model of four-party schemes. These moves were followed in 2015 by the introduction of the Interchange Fee Regulation (IFR), which introduced price rules to nurture a competitive, innovative and secure payments environment for all stakeholders. The IFR caps the interchange fees on consumer debit and credit cards and prohibits restrictions on co-badging and certain requirements to honour all cards for merchants. This paper assesses the impact of the IFR. Based on a literature review and data analysis, it concludes that the IFR has led to a drop in interchange fees – in some cases below the maximum defined in the legislation in all EU member states. The decrease in the interchange fee is largely reflected in lower charges for merchants, although the reduction is – at least partially – offset by higher scheme fees charged by international four-party card schemes and by higher fees for cardholders. The policy recommendations aim to increase transparency for a fuller understanding of the functioning of the market and to enhance competitiveness in both the market for card payments and other payment instruments

Physiocracy: Leading political and social-economic system of the XVIIIth Century in France

In France the XVIIIth century was characterized by the Enlightenment as a philosophical phenomenon and Physiocracy as an expression of new economic thinking. But the Physiocrats were not merely a school of economic thought, they were also a school of political action. Kings, princes and high public servants were among their pupils. The great French Revolution itself was influenced by their writings. And the force of their work is still not fully spent. In order to appreciate the theory and significance of the Physiocracy it is necessary to take into account the circumstances of its time. Physiocracy is a doctrine which esteems that agriculture is of more importance than industry and commerce. In the above article the following subjects of the physiocratic doctrine are dealt with: the natural order, property and liberty; the relations between the government and the individual citizen, the theory of the produit net and the Tableau Économique of François Quesnay. The evaluation also includes the question about the expansion of Physiocracy. Indeed, it had many followers in several countries of Europe and was also the first real School of economic thinking. By its systematic approach, Physiocracy established the economy as a science. All the aspects of Physiocracy which have been mentioned above are intimately bound together and are in several aspects the economic precursor of the French Revolution.the relations between the government and the individual citizen; physiocracy; the authority of individuals; the sovereign authority

A 5-MHz 11-bit delay-based self-oscillating ΣΔ modulator in 0.025 mm2

In this paper a self-oscillating Sigma Delta modulator is presented. By introducing this self-oscillation in the system, the loop filter operates at a speed significantly lower than dictated by the clock frequency. This allows for a simple and power efficient design of the opamps used in the loop filter. The self-oscillation is induced here by introducing a controlled delay in the feedback loop of the modulator. A second order CMOS prototype was constructed in a 0.18 um technology. A clock frequency of 850MHz generates a self-oscillation mode at 106.25 MHz. The modulator achieves a dynamic range (DR) of 66 dB for a signal bandwidth of 5 MHz. The power consumption is only 6mW and the chip area of the modulator core is 0.025mm^2