A concept-driven algorithm for clustering search results

Without search engines, the Internet would be an enormous amount of disorganized information that would certainly be interesting but perhaps not very useful. Search engines help us in all kinds of tasks and are constantly improving result relevance. The Lingo algorithm combines common phrase discovery and latent semantic indexing techniques to separate search results into meaningful groups. It looks for meaningful phrases to use as cluster labels and then assigns documents to the labels to form groups.     

Single-quantum well InGaN green light emitting diode degradation under high electrical stress

We performed a degradation study of high-brightness Nichia single-quantum well AlGaN/InGaN/GaN green light-emitting diodes (LEDs). The devices were subjected to high current electrical stress with current pulse amplitudes between 1 and 7 A and voltages between 10 and 70 V with a pulse length of 100 ns and a 1 kHz repetition rate. The study showed that when the current amplitude was increased above 6 A, a fast (about 1 s) degradation occurred, with a visible discharge between the p- and n-type electrodes. Subsequent failure analysis revealed severe damage to the metal contacts, which lead to the formation of shorts in the surface plane of the diode. For currents smaller than 6 A, a slow degradation was observed as a decrease in optical power and an increase in the reverse current leakage. However, a rapid degradation occurred between 24 and 100 h which was similar to the rapid degradation observed at higher currents. The failure analysis results indicate that the degradation process begins with carbonization of the plastic encapsulation material on the diode surface, which leads to the formation of a conductive path across the LED and subsequently to the destruction of the diode itself.     

Spiral-wrapped Tubing as Electrical Insulation

Spiral wrapped tubing obtains the best characteristics of film combinations with accurate dimensional control.     

Oxidised mannan antigen conjugates preferentially stimulate T1 type immune responses

It is desirable to be able to produce either T1 or T2 responses and we have found that, in mice, mannose--coupled antigens stimulated T2 type responses antibodies and CTLs, whereas if oxidized, mannose--coupled antigens stimulated T1 responses little antibody and a potent CTL response. In addition, the cytokine profiles support the T1rT2 differentiation with these immunizations, in that oxidized mannan antigen gives IFNg, IL-2 and IL-12 production, whereas in the absence of oxidization, IL-4 and not the other cytokines is produced. A number of antigens have been examined--particularly Mucin 1 and the delivery method using mannose may be applicable to the other antigens.     

Mathematical model for gas flow through a packed bed in the presence of sources and sinks

Flow within a packed bed is normally calculated by attempting to simultaneously satisfy the continuity and Ergun equations. However, the presence of gas sources/sinks within the bed escalates the complexity of the problem, particularly when the flow is two-dimensional and a solution to the full Ergun equation is required. In quest of an efficient and dependable algorithm for the calculation of gas flow, a critical review of existing solution methods was undertaken and a new method, ‘FLOW’, is now proposed. The technique retains the viscous and inertial pressure gradient terms of the Ergun equation, and both are treated as linear functions of the flow. Solutions are approached iteratively; using finite difference techniques, the continuity and linearized Ergun equations are solved for the pressure field; a new flow field is then calculated from which is derived an adjustment to the inertial resistance term of the Ergun equation. The sequence is repeated until satisfactory convergence is obtained. Relatively few iterations are normally required and, for the case of negligible inertial pressure drop, one calculation cycle is sufficient. A comparison of results obtained using the ‘FLOW’, modified ‘SIMPLE’ and vorticity procedures is presented. The proposed method allow flexibility in the specification of boundary conditions and can be applied to compressible or incompressible flow, as well as for the case of nonisothermal beds.