Optimal joint path computation and resource allocation policies in EPC networks

The 3GPP Evolved Packet System (EPS) is the new system for mobile communications. Such system is composed at a radio access, called Long Term Evolution (LTE), and an IP backbone architecture called Evolved Packet Core (EPC). At high-level view, flows are rep- resented by bearers. A bearer is a virtual path that connects a user equipment to the egress gateway of the EPS, that is the Packet Data Network Gateway (PDN-GW). The topic investigated within this the- sis is how to route flows in the EPC so as to meet the QoS guarantees included in the bearer while optimizing network resources. In the EPC, bearer can be pre-empted when network resources are scarce. Therefore, route computation should also be judged by the number of pre-emptions that that it forces in the network. Three different routing optimization models with different behaviours were developed within this thesis which incorporate pre-emption in different ways. We have tested these models in realistic networks as the blocking proba- bility, pre-emption probability and time overhead. Our results show that the algorithms exhibits similar behaviours as the blocking and pre-emption probability. Moreover, blocking and pre-emption seems to be contrasting goals one is reduced at the expenses of the other. As for time overhead, computations on off-the-shelf hardware show that an optimization approach is compatible with a highly-dynamic large-scale environment

Anterior-to-Posterior Migration of a Lumbar Disc Sequestration. Surgical Remarks and Technical Notes about a Tailored Microsurgical Discectomy

Extrusion of disc material within the spinal canal complicates up to 28.6% of lumbar disc herniations. Due to the anatomical "corridors" created by the anterior midline septum and lateral membranes, relocation occurs with an anterior and anterolateral axial topography. Posterior migration is an extremely rare condition and anterior-to-posterior circumferential migration is an even rarer condition. Its radiological feature can be enigmatic and since, in more than 50% of cases, clinical onset is a hyperacute cauda equina syndrome, it may imply a difficult surgical decision in emergency settings. Surgery is the gold standard but when dealing with such huge sequestrations, standard microdiscectomy must be properly modified in order to minimize the risk of surgical trauma or traction on the nerve roots

Innovative transport services in areas with weak and peculiar public transport demand

A growing demand for mobility and the deficiencies in the transport system have transformed urban centres in “unliveable” places. A prevalent use of private cars produces high levels of pollution, casualties and road congestion. The promotion of public transport is considered an effective strategy to make mobility more sustainable for people. When a public transport system serves areas with a weak transportation demand, as it happens in territories with dispersed settlements (urban outskirts, rural areas, mountains, …), the resort to unconventional forms of public transport, such as dial and ride bus services, is necessary

Analysis, characterization and minimization of IPMSMs cogging torque with different rotor structures

This paper presents the analysis, characterization and comparison of the cogging torque components generated by five different IPMSM rotor structures. More in detail, an IPMSM model (named IPMSM1), which is derived from a commercial geometry, is analyzed by using a Finite Element Method (FEM) approach. Then, four other IPMSM models, which are obtained by modifying the IPMSM1 rotor structure and by maintaining the same stator configuration, are proposed and analyzed. From the obtained simulation results, the cogging torque components for each structure are determined and compared. From this comparison, a significant cogging torque decrease is occurring for the modified geometries, without affecting the values of the generated torque. Furthermore, a meaningful relationship between the peak values of the cogging torque and the gradients of the flux density around the neutral area is reported and discussed. Therefore, simple structure modifications applied to the rotor geometry can bring significant improvements in terms of motor performances and cogging torque reductio

Contributed Review: Review of thermal methods for space charge measurement

The space charge accumulation phenomenon has garnered great interest over the last two decades because of the increased use of direct current in high voltage electrical systems. In this context, a significant relevance has been achieved by the thermal methods, used for solid dielectrics. This paper presents a review of this non-destructive measurement system used for the measurement of space charge. The thermal pulse method, the thermal step method, and the laser intensity modulation method are described. For each configuration, the principle of operation, the thicknesses analyzed, and the spatial resolution are described, reporting also the main related application

An IPMSM torque/weight and torque/moment of inertia ratio optimization

In this paper, a torque/weight and torque/moment of inertia ratio optimization procedure for interior permanent magnet syncronous motors (IPMSMs) is presented. More in detail, a performance comparison between several IPMSM rotor structures has been carried out in order to determine the optimum geometry that can maximize the torque/weight and torque/moment of inertia ratios. A commercial motor, with known electrical and mechanical characteristics, has been taken as reference. Its rotor structure has been modified several times, obtaining different rotor geometries and, therefore, many IPMSM models with different electrical and mechanical characteristics. The finite element method (FEM) analysis of each IPMSMs has been performed using the software FEMM, allowing to determine the related torque/load-angle characteristics. From the comparison between the torque/load-angle characteristics of the different IPMSM structures, it can be stated that significant performance improvements can be obtained in dependence not only of the type of permanent magnets and their direction of magnetization, but also of the PM displacement within the rotor

GM Allotypes and COVID-19. A Pilot Study Performed on Sicilian Patients

Several studies suggest that genetic variants that influence the onset, maintenance and resolution of the immune response might be fundamental in predicting the evolution of COVID-19. In the present paper, we analysed the distribution of GM allotypes (the genetic markers of immunoglobulin γ chains) in symptomatic and asymptomatic COVID-19 patients and in healthy controls, all born and residing in Sicily. Indeed, the role played by GM allotypes in immune responses and infection control is well known. Our findings show that the GM23 allotype is significantly reduced in healthy controls. Interestingly, in a previous study, Sicilians carrying the GM23 allotype were associated with the risk of developing a symptomatic Human Cytomegalovirus infection. However, a note of caution should be considered, due to the small sample size of patients and controls

Effect of Ischemia–Reperfusion on Renal Expression and Activity of <i>N</i> G-<i>N</i> G-Dimethylarginine Dimethylaminohydrolases

Background Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of nitric oxide synthase. It is degraded by the enzyme dimethylarginine dimethylaminohydrolase (DDAH). Methods Rats (n = 50) underwent to 45 min of renal ischemia followed by 30 min, 1 h, and 3 h of reperfusion. Expression of endothelial nitric oxide synthase, inducible nitric oxide synthase, DDAH-1, DDAH-2, renal DDAH activity, plasma NO2(-)/NO3(-), and ADMA levels were evaluated. Results Inducible nitric oxide synthase expression increased, as confirmed by both plasma (11.89 +/- 1.02, 15.56 +/- 0.93, 11.82 +/- 0.86, 35.05 +/- 1.28, and 43.89 +/- 1.63 nmol/ml in the control, ischemic, 30-min, 1-h, and 3-h groups, respectively) and renal (4.81 +/- 0.4, 4.85 +/- 1, 9.42 +/- 0.7, 15.42 +/- 0.85, and 22.03 +/- 1.11 nmol/mg protein) formations of NO2(-)/NO3(-). DDAH-1 expression decreased after reperfusion, whereas DDAH-2 increased after 30 min, returning to basal levels after 3 h. Total DDAH activity was reduced during all times of reperfusion. Both plasma (0.41 +/- 0.03, 0.43 +/- 0.05, 0.62 +/- 0.02, 0.71 +/- 0.02, and 0.41 +/- 0.01 nmol/ml in the control, ischemic, 30-min, 1-h, and 3-h groups, respectively) and renal (1.51 +/- 0.01, 1.5 +/- 0.01, 1.53 +/- 0.01, 2.52 +/- 0.04, and 4.48 +/- 0.03 nmol/mg protein in the control, ischemic, 30-min, 1-h, and 3-h groups, respectively) concentrations of ADMA increased. Conclusions Results suggest that ischemia-reperfusion injury leads to reduced DDAH activity and modification of different DDAH isoform expression, thus leading to increased ADMA levels, which may lead to increased cardiovascular risk