Extending hoare logic to real-time

Classical Hoare triples are modified to specify and design distributed real-time systems. The assertion language is extended with primitives to express the timing of observable actions. Further the interpretation of triples is adapted such that both terminating and nonterminating computations can be specified. To verify that a concurrent program, with message passing along asynchronous channels, satisfies a real-time specification, we formulate a compositional proof system for our extended Hoare logic. The use of compositionality during top-down design is illustrated by a process control example of a chemical batch processing system.     

Extending hoare logic to real-time

Classical Hoare triples are modified to specify and design distributed real-time systems. The assertion language is extended with primitives to express the timing of observable actions. Further the interpretation of triples is adapted such that both terminating and nonterminating computations can be specified. To verify that a concurrent program, with message passing along asynchronous channels, satisfies a real-time specification, we formulate a compositional proof system for our extended Hoare logic. The use of compositionality during top-down design is illustrated by a process control example of a chemical batch processing system.     

Effect of sintering parameters (time and temperature) upon the fabrication process of organic binder-based metallic hollow sphere

Metallic hollow spheres (MHSs) are developed to be used in structural applications in syntactic and metal foams. These foams are lightweight and energy-absorbing structures which also can be used for acoustic insulation. In this study, the fabrication process of MHSs with optimum mechanical properties has been investigated. To achieve this goal, polystyrene spheres were coated with iron powder and an organic binder. During the multi-stage heat treatment, the green spheres were sintered into MHSs. Sintering was done at various temperatures (1125, 1150, 1175 and 1200°C) at different durations (3:30, 4:30 and 5:30?h). The influence of the different sintering durations and temperatures on mechanical features, microstructure and density was studied as well. The obtained results indicate that samples that were sintered at the temperature of 1175°C for 4:30?h resulted in superior mechanical and physical properties.     

Harmonic cancellation characteristics of specially connected transformers

Specially connected transformers such as V–V, Scott and Le-Blanc transformers are used to convert a three-phase supply into one or two single-phase supplies. These transformers are commonly used in the electro locomotive traction systems. This paper investigates the harmonic cancellation characteristics of such transformers. The results show that when two harmonic-producing loads are connected to each single-phase side of the transformers, the harmonics produced by the loads will cancel out at the primary sides of the transformers. The amount of cancellation is affected by transformer type and harmonic order. The study is performed for seven types of specially connected transformers.     

Invited review: Microbiota of the bovine udder: Contributing factors and potential implications for udder health and mastitis susceptibility

Various body sites of vertebrates provide stable and nutrient-rich ecosystems for a diverse range of commensal, opportunistic, and pathogenic microorganisms to thrive. The collective genomes of these microbial symbionts (the microbiome) provide host animals with several advantages, including metabolism of indigestible carbohydrates, biosynthesis of vitamins, and modulation of innate and adaptive immune systems. In the context of the bovine udder, however, the relationship between cow and microbes has been traditionally viewed strictly from the perspective of host-pathogen interactions, with intramammary infections by mastitis pathogens triggering inflammatory responses (i.e., mastitis) that are often detrimental to mammary tissues and cow physiology. This traditional view has been challenged by recent metagenomic studies indicating that mammary secretions of clinically healthy quarters can harbor genomic markers of diverse bacterial groups, the vast majority of which have not been associated with mastitis. These observations have given rise to the concept of “commensal mammary microbiota,” the ecological properties of which can have important implications for understanding the pathogenesis of mastitis and offer opportunities for development of novel prophylactic or therapeutic products (or both) as alternatives to antimicrobials. Studies conducted to date have suggested that an optimum diversity of mammary microbiota is associated with immune homeostasis, whereas the microbiota of mastitic quarters, or those with a history of mastitis, are considerably less diverse. Whether disruption of the diversity of udder microbiota (dysbiosis) has a role in determining mastitis susceptibility remains unknown. Moreover, little is known about contributions of various biotic and abiotic factors in shaping overall diversity of udder microbiota. This review summarizes current understanding of the microbiota within various niches of the udder and highlights the need to view the microbiota of the teat apex, teat canal, and mammary secretions as interconnected niches of a highly dynamic microbial ecosystem. In addition, host-associated factors, including physiological and anatomical parameters, as well as genetic traits that may affect the udder microbiota are briefly discussed. Finally, current understanding of the effect of antimicrobials on the composition of intramammary microbiota is discussed, highlighting the resilience of udder microbiota to exogenous perturbants.     

A modified moment resisting connection for ductile steel frames (Numerical and experimental investigation)

The seismic behavior of steel moment resisting building systems are directly affected by the local behavior of beam to column connections. In welded connections, severe stress concentrations at the connection edge coupled with imperfections of the weld roots, may contribute to significant reduction of the seismic performance. In this study, a reduced plate section connection is proposed to shift the stress concentration from the connection face. With this aim, the authors propose drilled holes at cover plates to create an intentional weak point. Applying this method, the stress concentration at the weld roots is significantly diminished and the failure mechanism is altered from premature weld fracture to ductile plate yielding around the holes. This technique eliminates unfavorable local beam failures present in some similar methods and also forces the cover plate to behave as the replaceable fuse of the connection system. As it is revealed from the finite element and experimental investigations, the strength and ductility capacity of the considered connection type is significantly improved and the behavior of the connection seems to be far less dependant of the weld root quality. This might improve the structural reliability of the connection due to the guided failure mechanism.     

A new approach to accurate measurement of uniaxial joint angles based on a combination of accelerometers and gyroscopes

A new method of measuring joint angle using a combination of accelerometers and gyroscopes is presented. The method proposes a minimal sensor configuration with one sensor module mounted on each segment. The model is based on estimating the acceleration of the joint center of rotation by placing a pair of virtual sensors on the adjacent segments at the center of rotation. In the proposed technique, joint angles are found without the need for integration, so absolute angles can be obtained which are free from any source of drift. The model considers anatomical aspects and is personalized for each subject prior to each measurement. The method was validated by measuring knee flexion-extension angles of eight subjects, walking at three different speeds, and comparing the results with a reference motion measurement system. The results are very close to those of the reference system presenting very small errors (rms = 1.3, mean = 0.2, SD = 1.1 deg) and excellent correlation coefficients (0.997). The algorithm is able to provide joint angles in real-time, and ready for use in gait analysis. Technically, the system is portable, easily mountable, and can be used for long term monitoring without hindrance to natural activities.     

An introduction to compositional methods for concurrency and their application to real-time

Formal methods to specify and verify concurrent programs with synchronous message passing are discussed. We stress the development towards compositional methods, i.e. methods in which the specification of a compound program can be inferred from specifications of its constituents without reference to the internal structure of those parts. Compositionality enables verification during the process of (top-down) design — the derivation of correct programs — instead of the more familiar a-posteriori verification based on already completed program codes. We sketch the transition from non-compositional towards compositional methods for concurrent programs, indicating the main principles behind compositionality. Having achieved a compositional framework based on classical Hoare triples, we discuss extensions to achieve a convenient formalism to specify and verify reactive systems that have an intensive interaction with their environment. Next this Hoare-style framework is adapted to specify and verify real-time properties, and a compositional proof method is formulated for real-time distributed computing. Compositional reasoning during top-down development of a real-time program is illustrated by an example concerning a watchdog timer. This work was partially supported by Esprit-bra project 3096: Formal Methods and Tools for the Development of Distributed and Real-Time Systems (spec).     

L∞ Parameter estimates for volumetric error in models of machine tools

Software error compensation is becoming an increasingly important aspect of numerically controlled machine tools. Currently, the error models are identified using the least-squares criterion. This criterion does not necessarily reflect the evaluation criteria of a machine's performance. In this paper, we develop a method for identifying the error model of a machine tool using a Chebyshev norm. The model parameter identification procedure becomes a linear program, and the resulting error models minimize the maximum error of the machine across its workspace thus affording strict on the errors produced by the machine.     

Laboratory-Scale Optimization of Roasting Conditions Followed by Aqueous Extraction of Oil from Wild Almond

The effects of roasting and aqueous extraction conditions for oil recovery from wild almond were optimized using response surface methodology (RSM). Optimum conditions for oil extraction were obtained at 142 °C roasting temperature, 16.5 min roasting time, 5.67 extraction pH and 4.6 h extraction time. Under these conditions, the extraction yield of 34.5% (w/w, based on the original weight of the sample) was obtained, which is equivalent to 80.0% of the total oil in the kernel. This was lower than that obtained by hexane Soxhlet (HS) extraction (43.1%, w/w, considered as 100% of total oil) but higher than that of cold pressing (CP) (18.5%, w/w; i.e., 42.9% of total oil). The refractive indices and saponification values of the oils were not affected by the extraction method. However, fatty acid and tocopherol compositions and DPPH radical scavenging capacities as well as unsaponifiable matter, iodine, peroxide and acid values of the obtained oils were impacted by the extraction method. The results showed that the quality attributes (omega-6 fatty acid content, peroxide and acid values, total tocopherol contents and antioxidant activity) of the oil obtained by AEP were somewhat similar to those of the oil extracted by CP and much superior to those of the oil obtained by HS.