On the computational complexity of bisimulation, redux

Paris Kanellakis and the second author (Smolka) were among the first to investigate the computational complexity of bisimulation, and the first and third authors (Moller and Srba) have long-established track records in the field. Smolka and Moller have also written a brief survey about the computational complexity of bisimulation [ACM Comput. Surv. 27(2) (1995) 287]. The authors believe that the special issue of Information and Computation devoted to PCK50: Principles of Computing and Knowledge: Paris C. Kanellakis Memorial Workshop represents an ideal opportunity for an up-to-date look at the subject.     

Design of multistandard adaptive voltage-controlled oscillators

A multistandard/multiband adaptive voltage-controlled oscillator (VCO) satisfying the phase-noise requirements of both second- and third-generation wireless standards is described in this paper (1.8-GHz DCS1800, 2.1-GHz wide-band code division multiple access, and 2.4-GHz wireless local area network, Bluetooth, and digital enhanced cordless telecommunications standards). The design procedure for the VCO is based on an adaptive phase-noise model. A factor of 12 reduction in power consumption with a phase-noise tuning range of 20 dB is demonstrated by adapting the VCO bias to the desired application. The VCO achieves -123-, -110-, and -103-dBc/Hz phase noise at 1-MHz offset in a 2.1-GHz band at supply currents of 6, 1.2, and 0.5 mA, respectively     

Effect of some manufacturing variables on formaldehyde release from particleboard: Relationship between different test methods

Different standard methods were used to determine the formaldehyde emission (FE) from particleboard; some of them were defined as European, Japanese and American standards. This study aimed to determine the effect of some manufacturing variables on FE of particleboards produced using melamine–urea–formaldehyde (MUF) adhesive with low content of free formaldehyde. The FE from the two types of particleboard (uncoated and laminated of 16–19 mm thickness) was measured with gas analysis method (EN 717-2) as well as the formaldehyde content (FC) with perforator method (EN 120). The European chamber (EN 717-1), Japanese desiccator method (JIS A 1460) and American large chamber (ASTM E 1333-96) values were measured by the conversion factor. The two types of particleboard studies showed differences in their formaldehyde parameters. It was concluded that the amount of formaldehyde emitted from the most of the manufactured boards resulted in the emission class El. In addition, laminating and decreasing the board thickness had a highly significant effect (p < 0.001) on decreasing the formaldehyde parameters. The particleboard E1-emission class had approximately the same value according to the test methods and similar behavior was observed in the relationship between the EN 120 values and EN 717-1, JIS A 1460, the proposed California Air Resource Board (CARB) Phase 1 and 2. This article considers how to estimate the FE values of the international test methods using the conversion factor to eliminate the need for time consuming and expensive equipment.     

Undecidability of domino games and hhp-bisimilarity

History preserving bisimilarity (hp-bisimilarity) and hereditary history preserving bisimilarity (hhp-bisimilarity) are behavioural equivalences taking into account causal relationships between events of concurrent systems. Their prominent feature is that they are preserved under action refinement, an operation important for the top-down design of concurrent systems. It is shown that, in contrast to hp-bisimilarity, checking hhp-bisimilarity for finite labelled asynchronous transition systems is undecidable, by a reduction from the halting problem of 2-counter machines. To make the proof more transparent a novel intermediate problem of checking domino bisimilarity for origin constrained tiling systems is introduced and shown undecidable. It is also shown that the unlabelled domino bisimilarity problem is undecidable, which implies undecidability of hhp-bisimilarity for unlabelled finite asynchronous systems. Moreover, it is argued that the undecidability of hhp-bisimilarity holds for finite elementary net systems and 1-safe Petri nets.     

Surface treatment of indomethacin agglomerates with eudragit

Indomethacin is a widely used anti-inflammatory drug with serious side-effects. This drug was used as a model drug for the coating of agglomerates with a permeable film (Eudragit NE). The agglomeration of the crystals increased the flowability of the bulk crystals. The coating further improved the flowability, and also the uniformity of the mass of the filled capsules. The coating film also influenced the wetting of the samples. The coating decreased the surface free energy and therefore reduced the adhesion forces between both the dry and the wet particles. The modification of the flow properties and the even capsule filling can be explained by this phenomenon. Since coating film does not dissolve in the artificial gastric juice, the dissolution test was performed only in the artificial intestinal juice. The dissolution of indomethacin from the coated sample was changed significantly. Accordingly, coating of the crystals can be performed in order to protect the mucosa of the gastrointestinal tract or to promote the preparation of solid dosage form.     

Automation of a precision temperature calibration laboratory

The objective of the paper is to discuss the automation of a precision calibration laboratory in the view of achieving maximal quality of metrological performance. Besides automation of measurement equipment for ease of operation, communication and data processing, basic emphasis is given to reliability of operation, flexibility, and possibility of achieving minimal uncertainty for given measurement equipment. Several software design guidelines are discussed in the case of automation of a high-precision temperature calibration laboratory     

A Novel Approach to Data Encryption Based on Matrix Computations

In this paper, we provide a new approach to data encryption using generalized inverses. Encryption is based on the implementation of weighted Moore–Penrose inverse A^†_MN(nxm) over the nx8 constant matrix. The square Hermitian positive definite matrix N_8x8 p is the key. The proposed solution represents a very strong key since the number of different variants of positive definite matrices of order 8 is huge. We have provided NIST (National Institute of Standards and Technology) quality assurance tests for a random generated Hermitian matrix (a total of 10 different tests and additional analysis with approximate entropy and random digression). In the additional testing of the quality of the random matrix generated, we can conclude that the results of our analysis satisfy the defined strict requirements. This proposed MP encryption method can be applied effectively in the encryption and decryption of images in multi-party communications. In the experimental part of this paper, we give a comparison of encryption methods between machine learning methods. Machine learning algorithms could be compared by achieved results of classification concentrating on classes. In a comparative analysis, we give results of classifying of advanced encryption standard (AES) algorithm and proposed encryption method based on Moore–Penrose inverse.     

The influence of different components on interpenetrating polymer network's (IPN's) characteristics as automotive top coats

The aim of this study was to investigate the influence of different components of interpenetrating polymer networks (IPNs) on their behavior in dual curing automotive applications. Dual curing is one of possible ways to obtain fast curing, scratch resistant coatings for use in OEM and car refinish applications. Dual curing systems, upon hardening, represent interpenetrating networks (IPNs) [1]. IPN's were obtained using novel acrylate-terminated hyperbranched polyester with high functionality and compared to classical 2-pack polyurethane clear coat.     

Effect of the sample sizes and the sampling conditions on the results of chemical analysis of castings of Cu−Sn and Cu−Sn−Pb alloys

In horizontal continuous casting of semifinished products made of alloys of the Cu−Sn and Cu−Sn−Pb systems segregation of tin and lead complicates the problem of obtaining the specified composition. The aim of this work consists in determining the size of the sample and the conditions for taking it in casting for which the specified chemical composition of the casting will be uniform over the entire volume. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 10, pp. 34–35, October, 1998.