Conversion and hydroconversion of hydrocarbons on zeolite-based catalysts: an FT-IR study

The interaction of HZSM5 and Mo-ZSM5 with benzene, naphthalene, toluene, ortho-xylene, para-xylene, n-butane, isobutane, n-heptane, and methylcyclohexane, in the range 100–773 K has been investigated using FT-IR spectroscopy. Hydrogen bonded species with the internal bridging and the external terminal OHs has been detected. The reactivity at high temperature has also been studied. The access to the internal cavities and to the strongly acidic OHs is at least partly hindered in the case of Mo-ZSM5. The catalytic activity of ZSM5 was moderated by the addition of molybdenum, with lower cracking and higher liquid yields.     

An FT-IR study of the adsorption of aromatic hydrocarbons and of 2,6-lutidine on H-FER and H-ZSM-5 zeolites

The interaction of aromatic hydrocarbons benzene, toluene, o-, m- and p-xylene and of methyl pyridines (in particular 2,6-lutidine) with H-ZSM-5 and H-FER zeolites has been studied. Two different H-ZSM-5 samples with strongly different intensity ratios between the two main OH stretching bands have been used. Benzene, toluene and p-xylene enter easily the cavities and give rise to three different H-bonded complexes. Two of them are strongly bonded while the third is likely a very hindered and distorted one. o-Xylene enters slowly the cavities and m-xylene even more slowly. Faster diffusion occurs at higher temperatures. On the contrary, xylenes do not enter the FER cavities. In spite of its steric hindrance, supposed to be the same of m-xylene, 2,6-lutidine enters fast the ZSM channels and is protonated by the internal sites. On the contrary, it does not enter the FER cavities, but it is protonated too on the external silanols sites. Evidence is provided for some kind of heterogeneity of the internal sites of ZSM-5 zeolite. Additionally, it is concluded that other effects besides the molecular sieving effect may play a role in the access and diffusion of molecules into the zeolite channels.     

Common-Mode Response Overlapping vs. Shaping in Rail-to-Rail Op-Amp Input Stages

In this paper, a circuit technique—common-mode (CM) response overlapping—for maintaining the small-signal behavior of rail-to-rail amplifiers nearly constant over the whole input CM range, is introduced. This technique modifies the CM response of the rail-to-rail input stage adequately by means of two constant input floating voltage sources, which are adjusted by using a static tuning section. Its performance is compared with a second technique—CM response shaping—, which is also based on two variable input floating voltage sources, but relies on a dynamic feedback tuning loop. Experimental results obtained from two 3-V 0.8-m CMOS single-stage rail-to-rail amplifiers, which operate with CM response overlapping and shaping, respectively, are provided.     

An optimal decision-making approach for the management of radiotherapy patients

In this paper, novel integer programming formulations are developed for solving the optimal scheduling of patients waiting for radiotherapy treatment. In this specific clinical domain, the suitable management and control of a patients’ waiting list strongly affect both the quality of the therapeutical outcome, in terms of effectiveness, and the cost-saving use of the overall therapeutical resources, in terms of efficiency. The proposed models allow the best scheduling strategy to be devised by taking into account the quality of the health care service offered to the patient as well as the status and the preferences of the patient. The computational experiments, carried out on realistic scenarios and considering real data, are very promising and show the efficiency and robustness of the proposed models to address the problem under consideration.     

Push &; Pull: autonomous deployment of mobile sensors for a complete coverage

Mobile sensor networks are important for several strategic applications devoted to monitoring critical areas. In such hostile scenarios, sensors cannot be deployed manually and are either sent from a safe location or dropped from an aircraft. Mobile devices permit a dynamic deployment reconfiguration that improves the coverage in terms of completeness and uniformity. In this paper we propose a distributed algorithm for the autonomous deployment of mobile sensors called Push & Pull. According to our proposal, movement decisions are made by each sensor on the basis of locally available information and do not require any prior knowledge of the operating conditions or any manual tuning of key parameters. We formally prove that, when a sufficient number of sensors are available, our approach guarantees a complete and uniform coverage. Furthermore, we demonstrate that the algorithm execution always terminates preventing movement oscillations. Numerous simulations show that our algorithm reaches a complete coverage within reasonable time with moderate energy consumption, even when the target area has irregular shapes. Performance comparisons between Push & Pull and one of the most acknowledged algorithms show how the former one can efficiently reach a more uniform and complete coverage under a wide range of working scenarios.     

ATM layouts with bounded hop count and congestion

Summary. In this paper we introduce and analyze two new cost measures related to the communication overhead and the space requirements associated with virtual path layouts in ATM networks, that is the edge congestion and the node congestion. Informally, the edge congestion of a given edge e at an incident node u is defined as the number of VPs terminating at or starting from u and using e, while the node congestion of a node v is defined as the number of VPs having v as an endpoint. We investigate the problem of constructing virtual path layouts allowing to connect a specified root node to all the others in at most h hops and with maximum edge or node congestion c, for two given integers h and c. We first give tight results concerning the time complexity of the construction of such layouts for both the two congestion measures, that is we exactly determine all the tractable and intractable cases. Then, we provide some combinatorial bounds for arbitrary networks, together with optimal layouts for specific topologies such as chains, rings and grids. Received: December 1997 / Accepted: August 2000     

The effect of silicide on ESD performance of transistors

In this paper a new model for localized breakdown in NMOSTs under ESD stress is developed, which accounts for the reduced ESD strength in silicided devices. The model explains the impact of a stabilizing drain resistance on second breakdown current for both silicided and unsilicided protections.     

On the impact of mood on behavior: An integrative theory and a review.

Empirical evidence for effects of moods (both naturally occurring and experimentally manipulated) on behavior is reviewed in terms of an integrative theory: the mood-behavior model (MBM). It is posited that moods can influence behavior via 2 processes: (a) by informational effects on behavior-related judgments and appraisals, which in turn will result in behavioral adjustments (i.e., the informational mood impact on behavior), and (b) by influencing behavioral preferences and interests in compliance with a hedonic motive (i.e., the directive mood impact on behavior). The strength of the informational mood impact depends on moods' effective informational weight for behavior-related judgments and on mood-primed associations. The strength of the directive mood impact is predicted to be jointly determined by 2 variables: the strength of a hedonic motive and the instrumentality of possible acts for affect regulation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)