Experimental decomposition of the positive bias temperature stress‐induced instability in self‐aligned coplanar InGaZnO thin‐film transistors and its modeling based on the multiple stretched‐exponential functions

Decomposition of the positive gate‐bias temperature stress (PBTS)‐induced instability into contributions of distinct mechanisms is experimentally demonstrated at several temperatures in top‐gate self‐aligned coplanar amorphous InGaZnO thin‐film transistors by combining the stress‐time‐divided measurements and the subgap density‐of‐states (DOS) extraction. It is found that the PBTS‐induced threshold voltage shift (ΔV_T) consists of three mechanisms: (1) increase of DOS due to excess oxygen in the active region; (2) shallow; and (3) deep charge trapping in the gate insulator components. Corresponding activation energy is 0.75, 0.4, and 0.9 eV, respectively. The increase of DOS is physically identified as the electron‐capture by peroxide. Proposed decomposition is validated by reproducing the PBTS time‐evolution of I–V characteristics through the technology computer‐aided design simulation into which the extracted DOS and charge trapping are incorporated. It is also found that the quantitative decomposition of PBTS‐induce ΔV_T accompanied with the multiple stretched‐exponential models enables an effective assessment of the complex degradation nature of multiple PBTS physical processes occurring simultaneously. Our results can be easily applied universally to any device with any stress conditions, along with guidelines for process optimization efforts toward ultimate PBTS stability.     

Particle swarm optimization with mutation operations controlled by landscape modality estimation using hill-valley detection

Particle swarm optimization (PSO) is one of swarm intelligence algorithms and has been used to solve various optimization problems. Since the performance of PSO is much affected by the algorithm parameters of PSO, studies on adaptive control of the parameters have been done. Adaptive PSO (APSO) is one of representative studies. Parameters are controlled according to the evolutionary state, where the state is estimated by distance relations among a best search point and other search points. Also, a global Gaussian mutation operation is introduced to escape from local optima. In this study, a new adaptive control based on landscape modality estimation using hill-valley detection is proposed. A proximity graph is created from search points, hills and valleys are detected in the graph, landscape modality of an objective function is identified as unimodal or multimodal. Parameters are adaptively controlled as: parameters for convergence are selected in unimodal landscape and parameters for divergence are selected in multimodal landscape. Also, two mutation operations are introduced according to the modality. In unimodal landscape, a new local mutation operation is applied to the worst hill point which will be moved toward the best point for convergence. In multimodal landscape, a new adaptive global mutation operation is applied to all hill points for escaping from local optima. The advantage of the proposed method is shown by comparing the results of the method with those by PSO with fixed parameters and APSO.     

Determining comprehension and quality of TV programs using eye-gaze tracking

Currently, TV programs are evaluated by using questionnaires given after previews or by using TV ratings. There are few objective criteria useful for describing technical know-how about program production. One of the TV program producers’ concerns is how to choose expression methods that convey their ideas to viewers correctly and efficiently. Research has shown that eye-gaze direction is related to the human focus and attention. Gaze-based evaluations have been proposed for image-quality evaluations and certain usability tests. Such approaches are mainly based on how often a specific region attracted the subjects’ gaze or how long their gaze was fixed on it.To apply these approaches to TV programs, all the object regions that seem to attract a viewer's gaze need to be specified in advance. This causes several problems including the accuracy of specifying the region by using an image processing technique is not equal to the human subject's recognition ability and it is not feasible to manually specify such regions in an enormous number of frames (images) comprising the program. Further, how characteristics of well-produced TV programs appear on the viewer's gaze has not been objectively analyzed yet. There is a need to investigate the relationship between gaze and program contents which can be used as means for improving comprehension and quality of the TV programs. In this paper, we propose a new measurement and evaluating method for this purpose.This paper focuses on the relationship between a viewer's comprehension of a program and their gaze direction in a real experimental TV educational program involving 26 elementary school children and broadcast by NHK Broadcasting Corporation of Japan. Correlation between TV program comprehension and entropy is investigated. That is, variances in the gaze direction in relation to program comprehension are based on a entropy value that represents the degree of dispersion in each frame and is calculated from a probability density function estimated from the gaze directions. The results indicate that the variances of the gaze direction for scenes that gave better comprehension tended to be lower. This tendency was further noticeable after a keyword utterance were related to the answers of corresponding questions.     

On the RuO2TiO2 interlayer of PbO2 electrodeposited Ti anode

The degradation mechanism of electrodeposited β-PbO₂ on the RuO₂TiO₂ loaded Ti substrate was studied. The electric resistance of the PbO₂ anode was increased the Ti/Ru ratio of the interlayer and the current density of electrodeposition, probably due to oxidation of the interlayer at the initial stage of electrodeposition, so that the electric contact between PbO₂ and the interlayer might fail. The β-PbO₂ deposited anodes prepared carefully to avoid destructive oxidation of the interlayer were examined as the oxygen evolution electrode in 1 M H₂SO₄. The Ti substrate became passive, caused by permeation of oxygen through PbO₂ and the interlayer, when electrolysis was conducted for many hours. The service life time depended on the Ti/Ru ratio of the interlayer and the operating current density.     

Shear viscosity of the B phase of superfluid3He. III

We report the calculation of the shear viscosity in superfluid³He-B at 6, 21, and 30 bar. We have used the variational solution of the Boltzmann equation for quasiparticles. The transition probabilities are obtained within thes-p-d-wave approximation by fitting the normal state transport coefficients. The old and new Landau parameters are used to estimate the scattering amplitudes. The reduced shear viscosity does not depend very much on the choice of Landau parameters and agrees very well with experiment in the temperature range 0.5<t (=T/T _c )1.0, whereT _c is the transition temperature. We have also investigated the strong coupling corrections to the shear viscosity. Although the strong coupling corrections reduce the value of shear viscosity, the overall feature does not change from the weak coupling result. The pressure dependence of the reduced shear viscosity is found to be very small.     

Transesterification of phospholipids by acetone-dried cells of aRhizopus species immobilized on biomass support particles

Acetone-dried cells of aRhizopus species, immobilized on biomass support particles were applied to the transesterification between phosphatidylcholine and heptadecanoic acid. All eight species ofRhizopus tested exhibited good transesterification performance, with the immobilized cells ofR. niveus, R. delemar, andR. javanicus showing particularly high reaction rates which were equal to or exceeded that of a commercially available immobilized lipase preparation, Lipozyme IM60.