Synthesis of ZnO-based varistor precursor powders by means of the reaction spray process

High-purity, fine-grained oxide ceramic powders that are commonly used for ZnO-based varistors were synthesized by means of the reaction spray process. Processing steps included formation of the solutions of zinc nitrate and/or certain metal additives and spraying of the solution into a heated reaction column using a two-phase nozzle. After water evaporation from the droplets, the precursor salts were decomposed at elevated temperatures (up to 1473 K) in order to obtain homogeneous oxide powders with complex compositions corresponding to the final multicomponent varistor system. The decomposition behaviour of the precursors, as well as the characteristics of the resulting powders: crystallinity, phase composition, particle shape, morphology and particle-size distribution, were examined. It was shown that the characteristics of the reaction spray-derived powders can be controlled by adjusting the system and the solutions parameters.     

Analysis and implementation of the multiprocessor bandwidth inheritance protocol

The Multiprocessor Bandwidth Inheritance (M-BWI) protocol is an extension of the Bandwidth Inheritance (BWI) protocol for symmetric multiprocessor systems. Similar to Priority Inheritance, M-BWI lets a task that has locked a resource execute in the resource reservations of the blocked tasks, thus reducing their blocking time. The protocol is particularly suitable for open systems where different kinds of tasks dynamically arrive and leave, because it guarantees temporal isolation among independent subsets of tasks without requiring any information on their temporal parameters. Additionally, if the temporal parameters of the interacting tasks are known, it is possible to compute an upper bound to the interference suffered by a task due to other interacting tasks. Thus, it is possible to provide timing guarantees for a subset of interacting hard real-time tasks. Finally, the M-BWI protocol is neutral to the underlying scheduling policy: it can be implemented in global, clustered and semi-partitioned scheduling. After introducing the M-BWI protocol, in this paper we formally prove its isolation properties, and propose an algorithm to compute an upper bound to the interference suffered by a task. Then, we describe our implementation of the protocol for the?LITMUS ^RT real-time testbed, and measure its overhead. Finally, we compare M-BWI against FMLP and OMLP, two other protocols for resource sharing in multiprocessor systems.     

Subsumptive general solutions and parametric general solutions of Post equations

In this paper we generalize Rudeanu’s results from [13] to Post algebras. We give a necessary and sufficient condition for the existence of a Post function f such that the set of solutions of equation f(x) = 0 is a given interval. We also prove that every Post transformation is the parametric solution of some consistent Post equation.     

Request redirection paradigm in medical image archive implementation

It is widely recognized that the JPEG2000 facilitates issues in medical imaging: storage, communication, sharing, remote access, interoperability, and presentation scalability. Therefore, JPEG2000 support was added to the DICOM standard Supplement 61. Two approaches to support JPEG2000 medical image are explicitly defined by the DICOM standard: replacing the DICOM image format with corresponding JPEG2000 codestream, or by the Pixel Data Provider service, DICOM supplement 106. The latest one supposes two-step retrieval of medical image: DICOM request and response from a DICOM server, and then JPIP request and response from a JPEG2000 server. We propose a novel strategy for transmission of scalable JPEG2000 images extracted from a single codestream over DICOM network using the DICOM Private Data Element without sacrificing system interoperability. It employs the request redirection paradigm: DICOM request and response from JPEG2000 server through DICOM server. The paper presents programming solution for implementation of request redirection paradigm in a DICOM transparent manner.     

A platform for the development of patient applications in the domain of personalized health

Personalized health (p-health) systems can contribute significantly to the sustainability of healthcare systems, though their feasibility is yet to be proven. One of the problems related to their development is the lack of well-established development tools for this domain. As the p-health paradigm is focused on patient self-management, big challenges arise around the design and implementation of patient systems. This paper presents a reference platform created for the development of these applications, and shows the advantages of its adoption in a complex project dealing with cardio-vascular diseases.     

Proactive thermal management in green datacenters

The increasing demand for faster computing and high storage capacity has resulted in an increase in energy consumption and heat generation in datacenters. Because of the increase in heat generation, cooling requirements have become a critical concern, both in terms of growing operating costs as well as their environmental and societal impacts. Presently, thermal management techniques make an effort to thermally profile and control datacenters’ cooling equipment to increase their efficiency. In conventional thermal management techniques, cooling systems are triggered by the temperature crossing predefined thresholds. Such reactive approaches result in delayed response as the temperature may already be too high, which can result in performance degradation of hardware.     

The investigation of metastable ζ-hcp phase in the Ag-rich f c c region of Ag-In alloys rapidly quenched from the melt

Stacking faults, which were detected in the Ag-In system, have been examined by transmission electron microscopy and electron diffraction. An enhanced concentration of stacking faults in splat cooled specimens as well as the formation of a metastable hexagonal phase in the f c c region of the alloy was observed. As far as we know this is the first case of the terminal solid solubility being reduced by rapid quenching. Terminal solid solubility is reduced because of the high concentration of structural defects introduced by quenching, e.g. dislocations and stacking faults, which serve as the nuclei for the transformation from the f c c to the h c p structure. Our measurements and calculations show that the stacking fault energy minimum is shifted to lower electron concentrations with respect to the stacking fault energy minimum corresponding to the equilibrium phase boundary for the f c c-h c p transformation. The new metastable phase boundary for this transformation was confirmed by X-ray examinations. We explain this earlier h c p phase appearance in rapid quenched specimens as the consequence of enhanced interaction of the Fermi surface and contracted Brillouin zone. The Brillouin zone contraction we attributed to quenched-in vacancies.     

Oxidation of formic acid at a high surface area supported platinum modified by foreign metal adatoms

The anodic oxidation of formic acid was studied on platinum distributed in the form of small particles in a porous substrate modified by metal adatoms deposited at underpotentials. The rate of the reaction was greatly enhanced on the commercial catalyst Powercat 3000 (PC 3000). The hydrogen adsorption and the underpotential deposition of several metals at PC 3000 were shown to be dissimilar to that at smooth polycrystalline Pt. Steady-state and long-term experiments were performed to determine the stability of this electrode.