Transfer function and near-field detection of evanescent waves

We consider characterization of a near-field optical probe in terms of detection efficiency of different spatial frequencies associated with propagating and evanescent field components. The former are both detected with and radiated from an etched single-mode fiber tip, showing reciprocity of collection and illumination modes. Making use of a collection near-field microscope with a similar fiber tip illuminated by an evanescent field, we measure the collected power as a function of the field spatial frequency in different polarization configurations. Considering a two-dimensional probe configuration, numerical simulations of detection efficiency based on the eigenmode expansion technique are carried out for different tip apex angles. The detection roll-off for high spatial frequencies observed in the experiment and obtained during the simulations is fitted using a simple expression for the transfer function, which is derived by introducing an effective point of (dipolelike) detection inside the probe tip. It is found to be possible to fit reasonably well both the experimental and the simulation data for evanescent field components, implying that the developed approximation of the near-field transfer function can serve as a simple, rational, and sufficiently reliable means of fiber probe characterization.     

Influence of microalloying on the mechanical properties of medium carbon forging steels after a newly designed post forging treatment

For more than twenty years the classical quench and tempering of medium carbon Cr-alloyed steels has been substituted in the production of drop-forged parts for the automotive industry by a direct continuous cooling of less expensive V-microalloyed steels with lower carbon content. However, this simplified treatment has serious limitations concerning the yield strength and ductility if compared with the properties after quench and tempering. On a group of such V-bearing steels additionally microalloyed with Ti and Nb and with different N contents, an alternative two-step-cooling (TSC) strategy after forging, combined with an additional annealing (AN), has been applied. This new post forging treatment results in a significant improvement of the final mechanical properties. The paper is focused on the particular contributions of a different microalloying in the optimized deformation schedules to improve mechanical properties after TSC + AN. The aim of this additional microalloying is to achieve a more homogeneous distribution of ferrite in the final multi-phase microstructure due to a proper austenite conditioning as well as to make a full use of the strengthening potential of vanadium in these forging steel grades.     

Pseudo-Additive Measures and Triangular-Norm-Based Conditioning

Conditioning in the framework of fuzzy measures (monotone normalized set functions vanishing in the empty set) is introduced. For every set B with non-null measure m(B) a conditional measure m _B , based on a triangular norm T, is introduced. Universal conditioning preserving the lower semi-continuity is shown to be necessarily based on some strict triangular norm. Then also each conditional measure m _B related to a pseudo-additive measure m is pseudo-additive. However, the pseudo-addition _B operating on the measures m _B is in general different from the pseudo-addition operating on the measure m. Specific cases of universal conditioning preserving the pseudo-addition are characterized. Classical probabilistic conditioning is shown to be a special case.     

Determination of CCT diagrams by thermal analysis after simulated hot deformation processes

By use of the hot deformation simulator (Wumsi) the plane strain hot compression test permits the simulation of hot forming processes up to a logarithmic strain of 2.5, whereby the cooling rate of the specimen after the deformation can be varied within a wide range. By employing a recently developed method the (residual) strengthening S of austenite is determined during any anisothermal deformation sequence by evaluating the flow curves. In this way the effective S-value, corresponding to the transformation start, can be established. In order to determine the transformation temperatures, the stored cooling curves are differentiated numerically, whereafter the transformation temperatures are marked on each cooling curve. Such marked cooling curves are plotted on a graph with zero time taken as the moment of crossing the A₃ temperature. The transformation lines can be traced through the markings, so that a complete continuous cooling transformation (CCT) diagram of a steel after a simulated hot deformation schedule can be obtained directly on the screen of a graphic terminal.     

Size-dependent electrophoretic migration and separation of liposomes by capillary zone electrophoresis in electrolyte solutions of various ionic strengths

The size-dependent electrophoretic migration and separation of liposomes was demonstrated and studied in capillary zone electrophoresis (CZE). The liposomes were extruded and nonextruded preparations consisting of phosphatidylcholine/phosphatidylglycerol/cholesterol in various ratios and ranging from 125 to 488 nm in mean diameter. When liposomes of identical surface charge density were subjected to CZE in Tris-HCl (pH 8) buffers of various ionic strengths (0.001-0.027), they migrated in order of their size. Size-dependent electrophoretic migration and separation of liposomes in CZE can be enhanced or brought about by decreasing the ionic strength of the buffer. It was shown that size-dependent migration is primarily a function of kappaR, where kappa(-1) is the thickness of the electric double layer (which can be derived from the ionic strength, I, of the buffer) and R, the liposome radius. Liposome mobility depends on kappaR and surface charge density in a manner consistent with that expected from the Overbeek-Booth electrokinetic theory. Thus, the relaxation effect appears to be the physical mechanism underlying the size-dependent electrophoretic separation of liposomes.     

Mechanistic insights derived from retardation and peak broadening of particles up to 200 nm in diameter in electrophoresis in semidilute polyacrylamide solutions

Rigid spherical particles in the size range of 5-200 nm diameter were subjected to capillary zone electrophoresis (CZE) in semidilute solutions of uncross-linked polyacrylamide of M(r) 5, 7 and 18 x 10(6) (PA-5, -7 and -18, respectively) of varying concentrations up to 1.6% and at field strengths varying from 68 to 270 V/cm. For all particles under study, the experimental Ferguson plots, log(mobility) vs. polymer concentration, permit a linear approximation. Their slope, the retardation coefficient KR = delta log (mobility)/delta (concentration), for particles smaller than 30 nm in diameter increased with particle size in PA-5 and -7 independently of electric field strength and polymer M(r). The KR of particles of 30 nm in diameter or more was found to be independent of particle size at the lowest field strength used but to decrease with it at the higher values of field strength. The decrease was parallel but shifted to higher values of retardation when the polymer M(r) increased from 5 to 7 x 10(6). With a decreasing ratio of average mesh size of the polymer network, zeta, to particle radius, R, the approach to "continuity" of the polymeric medium (zeta/R < 1) with both increasing particle size and polymer concentration does not result in the retardation behavior expected according to the macroscopic (bulk) viscosity of the solution. These experimental observations were hypothetically interpreted in terms of a transition to a retardation mechanism comprising the formation of a polymer depletion layer near the particle surface--polymer solution interface. Peak width exhibited an overall increase with PA-7 concentration for all particles studied. For particles of 30 nm in diameter or less, the increase was steepest when the radius of the particle was approximately commensurate with zeta at a given polymer concentration. For the largest particle, 205 nm in diameter, peak broadening with polymer concentration was found to correlate linearly with peak asymmetry. CZE of the particles in PA-18 solutions revealed abnormal behavior, with both mobility and peak width remaining near-constant up to a concentration of 0.08% and sharply declining at higher concentrations. The decline of relative mobility is the same-for the entire particle size range used, while peak width declines in direct relation to particle size.     

Weighted aggregation operators based on minimization

Minimization based aggregation operators A_g,D are discussed. Special attention is paid to weighting function g based cases related to some fixed dissimilarity function D. When D₂(x,y)=(x-y)², we recognize mixture operators and we recall some sufficient conditions for g ensuring the monotonicity of A_g,D. For D₁(x,y)=|x-y| and non-decreasing (non-increasing) g, A_g,D is shown to be the upper (lower) median whenever A_g,D is an aggregation operator.     

Some realizations and instances of Yager prioritized preference frame with application in evaluation and decision making

This study first revamps Yager prioritized ordered weighted averaging operators, and condenses them into a conceptual frame with putting aside one realization from Yager's original proposal. Then, based on elicited conceptual frame called Yager prioritized preference conceptual frame, this article proposes three distinct realizations to the conceptual frame with corresponding different instances, in which some evaluation models with weights determination methods are provided. Numerical examples are also presented immediately after every instance. Lastly, this study proposes the concepts of outer monotonic, inner monotonic, and global monotonic weights functions, and discusses some related properties, which are often embodied in preferences of decision makers.     

Failure analysis of integrated circuits beyond the diffraction limit: contact mode near-field scanning optical microscopy with integrated resistance, capacitance, and UV confocal imaging

Superresolution reflection near-field scanning optical microscopy (NSOM) of ultra-large-scale integrated circuits (ULSI) that have been subjected to chemical mechanical polishing (CMP) are presented. These NSOM images are rich in contrast, unlike simultaneously recorded atomic force microscopy (AFM) images. The NSOM data are compared to reflection confocal far-field optical microscopy using ultraviolet radiation with a wavelength of 248 nm, which has a resolution close to 0.2 /spl mu/m. Even though there is a significant thickness of oxide between the tip and the layer being imaged the data recorded with visible light clearly exhibits higher resolution than those ultraviolet confocal images that have undergone computer deconvolution. The AFM images exhibit no topography representing circuit features because the CMP operation that these static random access memory chips (SRAMs) have been subjected to produces flat topographic free surfaces. In terms of NSOM imaging, this is most interesting since the contribution of topography is totally removed and index of refraction variations are the only source for these rich NSOM images. Clearly, these NSOM images with cantilevered NSOM elements are free from topographic artifacts. Furthermore, simultaneous imaging of NSOM, normal force topography, and functional electrical characteristics such as capacitance and resistance are presented on these SRAMs. This demonstrates the ability of NSOM to act as a tool that provocatively integrates the best of far-field, optical imaging on the one hand with the most advanced scanned probe electrical imaging of circuit function on the other.