An investigation of the SCOZA for narrow square-well potentials and in the sticky limit

We present a study of the self consistent Ornstein-Zernike approximation (SCOZA) for square-well (SW) potentials of narrow width delta. The main purpose of this investigation is to elucidate whether in the limit delta --> 0, the SCOZA predicts a finite value for the second virial coefficient at the critical temperature B2(Tc), and whether this theory can lead to an improvement of the approximate Percus-Yevick solution of the sticky hard-sphere (SHS) model due to Baxter [R. J. Baxter, J. Chem. Phys. 49, 2770 (1968)]. For SW of non vanishing delta, the difficulties due to the influence of the boundary condition at high density already encountered in an earlier investigation [E. Schoell-Paschinger, A. L. Benavides, and R. Castaneda-Priego, J. Chem. Phys. 123, 234513 (2005)] prevented us from obtaining reliable results for delta < 0.1. In the sticky limit this difficulty can be circumvented, but then the SCOZA fails to predict a liquid-vapor transition. The picture that emerges from this study is that for delta --> 0, the SCOZA does not fulfill the expected prediction of a constant B2(Tc) [M. G. Noro and D. Frenkel, J. Chem. Phys. 113, 2941 (2000)], and that for thermodynamic consistency to be usefully exploited in this regime, one should probably go beyond the Ornstein-Zernike ansatz.Comment: 40 pages, 13 figures. Previous Sec. 2 on the Yukawa potential has been removed. Only the square-well potential is considered in this versio

An Implementation of Role-Base Trust Management Extended with Weights on Mobile Devices

AbstractThis paper describes the implementation of a library for the management and evaluation of Role-based Trust Management (RT) credentials and policies written in RTML, also extended with weights, in mobile devices. In particular, it describes the implementation of the library in J2ME. It is worth noticing, that RTML credentials are XML-like documents and thus the capability of porting these features on mobile devices makes the overall framework very interoperable with other RT frameworks (as for GRID systems). As policy language, we use actually a variant of RTML, whose policies are added with weights and are able to express quantitative experience-based notions of trust. It allow also to encode certain reputation and recommendation models. The obtained results show how the implementation on mobile devices is feasible and the running time acceptable for several applications

New survey evidence: Renzi’s support is damaging the chances of a Yes vote in Italy’s referendum

When the Italian constitutional referendum was called, Italy’s Prime Minister, Matteo Renzi, linked the result to the fate of his government, suggesting that he would resign in the case of a No vote. Based on new survey evidence, Céline Colombo, Andrea De Angelis and Davide Morisi write that this strategy appears to have been counterproductive. They illustrate that voter support for the reform declines when it is explicitly linked to the government, but that if the Yes campaign focuses solely on the content of the reform, they may find consensus among a majority of voters on some of the key elements of the proposal

Surgical Strategy in Midline Tumours of the Anterior Cranial Fossa

Midline tumors of the anterior cranial fossa (ACF) are mostly represented by olfactory groove menigiomas (OGM). There are many different approaches to this complex anatomical area but only a few that allow from the beginning dural implant removal: purely endoscopic transnasal (EA), transcranial/transfrontal sinus (TFA), and combined EA-TFA (CA) approach. Despite the improvement of EA, the optimal treatment strategy for the surgical treatment of OGM is still a matter of debate. The most advocate advantages of the EA are the absence of cerebral retraction and the possibility to resect the dural implant of the tumor, thus reducing its vascularization. On the other hand, it presents several limits: an important sinonasal morbidity, the loss of olfaction as default, increased risk of postoperative CSF leakage (5-10% in referral centers), especially in anteriorly located tumors. Moreover, the EA is contraindicated in case of lateral (above the orbital floor) or anterior extension (posterior wall of frontal sinus), cerebral parenchima involvment, or in case of major nerves or artery encasement. Consequently, only little tumors extended to the tuberculum sellae or planum sphenoidalis could be safely resected through a purely EA. The TFA is performed by a bicoronal incision, creating a craniotomy on the anterior wall of the frontal sinus and drilling the posterior wall of the frontal sinus. It gives direct access to the dural attachment of the tumor and avoids any cerebral retraction. In case of bulky or far posterior tumors, the interhemispheric route is usually very effective. The TFA permits to remove OGM of any dimension, to deal with nerves of vessel encasement, and to respect meningohypophyseal arteries. The incidence of postoperative CSF leakage is minimal since the closure with the galea is of the utmost effectiveness (0% in our experience). In case of sinonasal involvement, a CA is usually preferred

Surgical Strategy in Midline Tumours of the Anterior Cranial Fossa

Midline tumors of the anterior cranial fossa (ACF) are mostly represented by olfactory groove menigiomas (OGM). There are many different approaches to this complex anatomical area but only a few that allow from the beginning dural implant removal: purely endoscopic transnasal (EA), transcranial/transfrontal sinus (TFA), and combined EA-TFA (CA) approach. Despite the improvement of EA, the optimal treatment strategy for the surgical treatment of OGM is still a matter of debate. The most advocate advantages of the EA are the absence of cerebral retraction and the possibility to resect the dural implant of the tumor, thus reducing its vascularization. On the other hand, it presents several limits: an important sinonasal morbidity, the loss of olfaction as default, increased risk of postoperative CSF leakage (5-10% in referral centers), especially in anteriorly located tumors. Moreover, the EA is contraindicated in case of lateral (above the orbital floor) or anterior extension (posterior wall of frontal sinus), cerebral parenchima involvment, or in case of major nerves or artery encasement. Consequently, only little tumors extended to the tuberculum sellae or planum sphenoidalis could be safely resected through a purely EA. The TFA is performed by a bicoronal incision, creating a craniotomy on the anterior wall of the frontal sinus and drilling the posterior wall of the frontal sinus. It gives direct access to the dural attachment of the tumor and avoids any cerebral retraction. In case of bulky or far posterior tumors, the interhemispheric route is usually very effective. The TFA permits to remove OGM of any dimension, to deal with nerves of vessel encasement, and to respect meningohypophyseal arteries. The incidence of postoperative CSF leakage is minimal since the closure with the galea is of the utmost effectiveness (0% in our experience). In case of sinonasal involvement, a CA is usually preferred

On Density Wave Instability Phenomena – Modelling and Experimental Investigation

Density Wave Oscillations (DWOs) are dealt with in this work as the most representative instabilities frequently encountered in the boiling systems. This dynamic type instability mode – resulting from multiple feedback effects between the flow rate, the vapour generation rate and the pressure drops in the boiling channel – constitutes an issue of special interest for the design of industrial systems and equipments involving vapour generation. The chapter is structured as follows. Physical insight into the distinctive features leading to DWO mechanism is provided in Section 2. Modelling and experimental investigations on instability phenomena available from the open literature are described in Section 3. Section 4 and 5 present the analytical modelling developed in this work for DWO theoretical predictions, whereas numerical modelling (using RELAP5 and COMSOL codes) is briefly discussed in Section 6. Modelling efforts start necessarily from the simplifying and sound case of straight vertical tube geometry, which is referenced for validating the whole modelling tools. Description of the experimental campaign for DWO characterization in helical coil tubes is shortly presented in Section 7. The peculiar influence of the helical shape on the instability occurrence is examined in Section 8. Suited modifications of the models are introduced in order to simulate the experimental results

On-site monitoring of the performance of innovative treatments for marble conservation in architectural heritage

Innovative nanostructured treatments for stone conservation, based on dispersions of photoactive TiO2 nanoparticles, recently studied in our research group, provided interesting results after laboratory testing. Unfortunately, it is almost impossible to accurately reproduce in the lab the complexity of field exposure conditions. It is then of crucial importance to evaluate the behaviour and durability of new treatments in situ, once they are applied to real deteriorated surfaces of the architectural heritage exposed in outdoor. In the present research, the effectiveness of a TEOS-nano-TiO2 treatment and of two nanocomposites based on nano-TiO2 dispersion in organosiloxane and functionalized SiO2 for the protection of two specific marbles—Candoglia and Crevoladossola—has been evaluated on-site. The effect of the introduction of innovative titania nanoparticles in selected commercial products has been examined focusing on compatibility and protection efficacy in real exposure condition. An on-site testing protocol has been defined and carried out for 12 months after the application, considering colour and morphology changes and water absorption by capillarity. The nano-TiO2 addition does not hinder the performance of the protective treatments while it provides a positive contribution in soiling reduction. The results will be implemented in the operative framework of the ongoing conservation project of the considered historical façade

A Fast Autotuning Method for Velocity Control of Mechatronic Systems

In this paper a fast automatic tuning methodology for velocity controllers of mechatronic systems is proposed. In order to be applicable in general, the method takes into account the position, velocity and torque constraints of the motion control system and it requires a minimum intervention of the operator. Further, it can be implemented also with small computational capabilities which makes it suitable for industrial drives. Simulation results show the effectiveness of the technique

An Hardware-in-the-Loop Tool for the Design of Complex Mechanical Systems Controllers

In this paper we propose an Hardware-In-the-Loop (HIL) system for industrial drives. The system allows the user to optimize the design of control strategies by emulating complex mechanical applications. In fact, with this approach it is possible to simulate the behavior of the real mechanical system, and therefore to verify a priori the effectiveness of a control strategy and to achieve a rapid prototyping of the mechatronic system. The structure of the system consists of a couple of brushless motor which are connected by a mechanical joint. In one drive the control functions related to a specific application are implemented while the other one is used to replicate the mechanical system model of the application. A modular approach has been selected in order to allow a rapid development of a given application. In particular, a library of components has been implemented both in Simulink and in an IEC61131-3 language