A unified sequential identification structure based on convergence considerations

This paper presents a unified approach to sequential identification methods, via identification-convergence considerations, such that a fixed-structure identifier of stable and unstable processes is derived. It is shown that various identification algorithms can be derived by a proper choice of identifier parameters subject to simple constraints. Specifically, stochastic approximation and sequential learning identification algorithms are shown to be special cases of the above unified sequential structure, as are other algorithms.     

Mixed-mode fracture angle and fracture locus of materials subjected to compressive loading

The incipient fracture angle and fracture loci of prenotched brittle-like material subjected to compressive loading are investigated analytically and experimentally.The analysis of the problem includes parameters whose effects on fracture were pronounced via laboratory tests, namely: notch-tip curvature, subcritical microcracks emanating from the notch and crack closure process. Such considerations, jointly with the well-established fracture criteria in tensile loading (like the critical energy release rate, the critical energy density, J-integral and critical maximum stress used in this work) yielded an associated fracture locus for each criterion. Due to the mixed mode nature of the situation (K₁ and K₂) preevaluation of the fracture angle was instrumental.Data on critical (far-field) compressive load along with measured fracture angles performed on PMMA and Tungsten Carbide specimens are used to depict the most suitable fracture locus and thus to distinguish between the various fracture criteria when extended to fracture under compressive loading. An exact expression for the threshold load for complete closure of 2D elliptical cracks is used to delimit the fracture locus.     

Post Transmission Digital Video Enhancement for People with Visual Impairments

Image enhancement has been shown to improve the perceived quality of images and videos for people with visual impairments. The MPEG coding scheme makes spatial filtering, likely to help those with such impairments, possible at the decoding stage. We implemented a real-time platform for testing and improving contrast enhancement algorithms for MPEG video, with controls appropriate for the target population. The necessary additional processing runs efficiently on a general-purpose PC and can be integrated easily into existing MPEG-2 decoders. The system has enabled us to substantially improve the previous filtering algorithm; reducing artifacts exhibited in the previous implementation and should facilitate individual user-selection of enhancement parameters in evaluation studies.     

Online auctions enabling the secondary computer market

The Internet is enabling new forms of commerce and novel markets. One example is the secondary computer market, facilitating exchange between quality sensitive sellers, oftentimes businesses, and price sensitive buyers. As this market does not have a viable physical counterpart with reference prices, it is developing via online auctions. One question of interest in the evolution of this market is the determinants of prices. Using a dataset of 2,000 laptop auctions in a seven-month period, this research provides support for accepted auction theory while raising questions that deserve further explanation. The negative relationship between supply and auction price supports standard supply and demand theory, while higher prices for better features is consistent with vertical differentiation. Even within accepted theory this research broadens the understanding of auction behavior. There is clear support for the “price decline anomaly” where prices in sequential auctions decline, violating the “law of one price.” One result that deserves further attention is that midweek auctions realize higher prices. A second is that price changes over time are not monotonic. Future research should replicate and explain these results, as well as extend them to other auction settings. As the secondary computer market evolves it will impact the primary computer market.     

Microstructure and cutting performance investigation of Ti(C, N)-based cermets containing various types of secondary carbides

In this paper, the effects of type and amount of various secondary carbides on the microstructure and cutting performance of Ti(C_0.7N_0.3)–12Co system have been investigated. Nine alloys with different amounts of WC, Mo₂C and Ta_0.7Nb_0.3C additives were studied, using scanning electron microscopy (SEM), Vickers hardness (HV), transverse rupture strength (TRS) and continuous turning tests. Alloys including Mo₂C and WC presented finer carbonitride grain structure, as well as higher wear resistance resulting from their higher hardness and highly solution hardened binder phase.     

On-line measurements in pig carcass classification: Repeatability and variation caused by the operator and the copy of instrument

For nearly all pigs slaughtered in the EU, the lean meat content is assessed on-line at the slaughter line. The assessment is made indirectly by an instrument performing a number of informative measurements including the thickness of back fat as one of the most important and common measurements. Several types of instruments are used for making the measurements. The quality of the calibration (the prediction ability) has to be approved by the EU Commission. However, the maintenance of instruments, training of operators, working conditions and other factors influencing the routine are quite as important for the accuracy as the calibration. As a part of an EU funded project, partners representing thirteen European countries have investigated the instruments used in their countries focusing on the precision of indirect measurements. The preconditions have differed considerably between the countries resulting in a wide range of estimates of the repeatability and the reproducibility (precision) of fat and muscle thickness. Totally, there have been three different types of manual instruments - invasive probe instruments from three manufacturers, non-invasive ultrasound and callipers. Furthermore, the precision of two automatic instruments with respect to lean meat content has partly been estimated. Even though neither the aim nor the design of the experiments was set for a direct comparison between different instruments, none of them seemed to deviate notably from the others with respect to the precision of fat thickness. In this study, the only investigated influencing factors were the variations in operators and copies of instruments. Generally, the variations between operators were more important than the variation between copies of the same type of instrument.     

Neutrino astronomy and gamma-ray bursts

The construction of large-volume detectors of high energy, greater than 1TeV, neutrinos is mainly driven by the search for extragalactic neutrino sources. The existence of such sources is implied by the observations of ultra-high-energy, greater than or equal to 1019eV, cosmic rays, the origin of which is a mystery. In this lecture, I briefly discuss the expected extragalactic neutrino signal and the current state of the experimental efforts. Neutrino emission from gamma-ray bursts (GRBs), which are probably sources of both high-energy protons and neutrinos, is discussed in some detail. The detection of the predicted GRB neutrino signal, which may become possible in the coming few years, will allow one to identify the sources of ultra-high-energy cosmic rays and to resolve open questions related to the underlying physics of GRB models. Moreover, detection of GRB neutrinos will allow one to test for neutrino properties (e.g. flavour oscillations and coupling to gravity) with an accuracy many orders of magnitude better than is currently possible.     

聚(三羟甲基丙烷-二庚酸-单丙烯酸酯)的合成及润滑性能

以三羟甲基丙烷-二庚酸-单丙烯酸酯为单体,以偶氮二异丁腈为引发剂,在乙酸乙酯中聚合得到聚酯。该聚酯具有聚α烯烃和酯类合成油的复合结构,具有良好的氧化安定性和剪切稳定性,其氧化诱导期高于常见基础油(矿物油和合成酯),起始热分解温度为259℃;同时,聚酯具有良好的润滑性能,可以作为润滑基础油或添加剂使用。     

Do two-dimensional "noble gas atoms" produce molecular honeycombs at a metal surface?

Anthraquinone self-assembles on Cu(111) into a giant honeycomb network with exactly three molecules on each side. Here we propose that the exceptional degree of order achieved in this system can be explained as a consequence of the confinement of substrate electrons in the pores, with the pore size tailored so that the confined electrons can adopt a noble-gas-like two-dimensional quasi-atom configuration with two filled shells. Formation of identical pores in a related adsorption system (at different overall periodicity due to the different molecule size) corroborates this concept. A combination of photoemission spectroscopy with density functional theory computations (including van der Waals interactions) of adsorbate-substrate interactions allows quantum mechanical modeling of the spectra of the resultant quasi-atoms and their energetics.