An alternative representation of coal composition data

The two best known coal composition charts are Seyler's plot of mass percent hydrogen versus mass percent carbon, which has been much used for coal classification, and van Krevelen's plot of atomic H/C ratio versus O/C ratio, which has proved useful in the study of coalification. For the more general problem of the study of conversion of coal to other materials it is suggested that a ternary carbon/ hydrogen/oxygen diagram be used. In particular it is advocated that the compositions be plotted as bond-equivalent percentages, i.e. with each element given a weighting appropriate to its power of combining with the other elements. The construction and use of the diagram are demonstrated, taking as an example the problem of the conversion of brown coal to oil.     

Operating system redundancy on an active,a stand-by or a passive basis

When applying redundancy, the system designer may find himself facing the dilemma of weighing the better life prospects of passive redundant hardware against the lower system complexity in the case of active redundant hardware. This dilemma is analyzed here by comparing the MTTF and the reliability obtained with active, stand-by and passive redundancy. The analysis makes use of Markov diagrams and a generalized reliability model that embraces all three types of redundancy and covers all types of failure which can occur in practice.     

Lithographically fabricated nanopore-based electrodes for electrochemistry

We report a new technique for fabricating electrodes for electrochemical applications with lateral dimensions in the range 15-200 nm and a reproducible, well-defined geometry. This technique allows determining the electrode size by electron microscopy prior to electrochemical measurements and without contamination of the metal electrode. We measured the diffusion-limited current with stepped-current voltammetry and showed that its dependence on electrode size can be quantitatively understood if the known geometry of the electrodes is explicitly taken into account.     

Occlusions and binocular stereo

Binocular stereo is the process of obtaining depth information from a pair of cameras. In the past, stereo algorithms have had problems at occlusions and have tended to fail there (though sometimes post-processing has been added to mitigate the worst effects). We show that, on the contrary, occlusions can help stereo computation by providing cues for depth discontinuities.We describe a theory for stereo based on the Bayesian approach, using adaptive windows and a prior weak smoothness constraint, which incorporates occlusion. Our model assumes that a disparity discontinuity, along the epipolar line, in one eyealways corresponds to an occluded region in the other eye thus, leading to anocclusion constraint. This constraint restricts the space of possible disparity values, thereby simplifying the computations. An estimation of the disparity at occluded features is also discussed in light of psychophysical experiments. Using dynamic programming we can find the optimal solution to our system and the experimental results are good and support the assumptions made by the model.     

A stochastic approach to consequence tree analysis

In this paper a stochastic approach to consequence tree analysis is considered. A consequence tree is a set of events logically combined by OR and AND connections that occur in sequence, some being prerequisites for others. Consequence trees are applicable to failure propagation in plants. Facilitating paths and inhibiting cuts are defined and considered. The distribution of the time the system needs to reach a certain top event is obtained. Probability weights are defined that can be used to obtain the weakest link in the consequence tree.     

A Generalised Asperity-Based Friction Model

Despite considerable research effort, the use of physics-based modelling to predict frictional behaviour is still a debatable question in modern tribological research. This article presents a dry-friction model, based on physical phenomena such as adhesion, elastic–plastic contact and deformation. This contribution offers a means to simulate all kinds of frictional behaviour that is observed in experimental research. The contact of two bodies through their surfaces is transformed into the contact of a body that is provided with asperities and containing material and geometrical information of both of the mating surfaces, and a counter profile, holding solely geometrical information. The local adhesion between the asperity tips and the counter profile, together with the elastic–plastic behaviour of the asperities themselves, form the basis for this model. The simulation results show qualitatively good agreement with experimental study. Friction and contact phenomena such as normal creep, increasing static coefficient of friction with increasing dwell time, pre-sliding hysteresis with nonlocal memory, Stribeck and viscous effect, frictional lag, stick–slip and dynamical oscillations are revealed by this model. Furthermore, future improvement and refinement of the model is possible (and ongoing) so as to incorporate lubrication and asperity wear.     

Combinatorial Strategies by Marine Cyanobacteria: Symplostatin 4, an Antimitotic Natural Dolastatin 10/15 Hybrid that Synergizes with the Coproduced HDAC Inhibitor Largazole

Combinatorial biosynthesis meets combinatorial pharmacology, cyanobacterial style : A new antimitotic natural product with features of both dolastatins 10 and 15 was isolated from the same Floridian Symploca sp. sample that produced the histone deacetylase inhibitor largazole. Both agents in combination are more effective in inhibiting cancer cell proliferation than either agent alone.