Degradation of bipolar transistor current gain by hot holes duringreverse emitter-base bias stress

Experimental evidences are given which demonstrate that degradation of the common-emitter forward current gain h_FE of submicron silicon npn bipolar transistors at low reverse emitter-base junction applied voltage is caused by primary hot holes of the n⁺ /p emitter tunneling current rather than secondary hot electrons generated by the hot holes or thermally-generated hot electrons. Experiments also showed similar kinetic energy dependence of the generation rate of oxide/silicon interface traps by primary hot electrons and primary hot holes. Significant h_FE degradation was observed at stress voltages less than 2.4 V     

Improving Usability Perception of Error-Prone AI Speakers: Elaborated Feedback Mitigates Negative Consequences of Errors

ABSTRACT

Users of voice user interface (VUI) often encounter errors, such as when a VUI attempts to recognize a user’s voice inputs or execute tasks. Conversation is prone to errors, and in the collaborative perspective, communicators manage common ground together to handle erroneous situations. Adopting a collaborative view of conversation, we propose that a VUI can address different types of errors by providing users with feedback to aid them in developing common ground to communicate more effectively. To test this proposal, we conducted a 2 (error type: recognition vs. execution error) × 2 (feedback elaboration: present vs. absent) mixed-design experiment in which users interacted with a VUI speaker and evaluated its usability in these four modes. Participants reported greater acceptance of feedback and higher usability perception for a speaker returning execution errors than for one returning recognition errors, particularly when the speaker presented feedback articulating reasons for the errors. This finding indicates that a VUI can employ feedback explaining the causes of errors to facilitate the development of common ground and to minimize the negative consequences of errors.     

Cathodic pulse breakdown of anodic films on aluminium in alkaline silicate electrolyte – Understanding the role of cathodic half-cycle in AC plasma electrolytic oxidation

Sequential anodic and cathodic pulse voltages were applied on anodised Al micro-electrodes in alkaline silicate electrolyte to explore the role of cathodic pulse in AC or bipolar plasma electrolytic oxidation (PEO) process. SEM observation was carried out to observe the sites of anodic and cathodic breakdown and their morphologies. The prior anodic breakdown accelerated the cathodic breakdown at ?50 V, and the acceleration was associated with the preferential cathodic breakdown at the anodic breakdown sites. However, the succeeding anodic breakdown during applying anodic pulse of 420 V for 2 ms was highly suppressed at the cathodic breakdown sites. This would randomise the anodic breakdown sites. Such role may contribute to the formation of rather uniform coatings on aluminium in this electrolyte without large discharge channels when larger cathodic current is applied with respect to the anodic current in AC PEO.     

Soluble‐eggshell‐membrane‐protein‐modified porous silk fibroin scaffolds with enhanced cell adhesion and proliferation properties

In this study, a porous silk fibroin (SF) scaffold was modified with soluble eggshell membrane protein (SEP) with the aim of improving the cell affinity properties of the scaffold for tissue regeneration. The pore size and porosity of the prepared scaffold were in the ranges 200–300 μm and 85–90%, respectively. The existence of SEP on the scaffold surface and the structural and thermal stability were confirmed by energy‐dispersive X‐ray spectroscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. The cell culture study indicated a significant improvement in the cell adhesion and proliferation of mesenchymal stem cells (MSCs) on the SF scaffold modified with SEP. The cytocompatibility of the SEP‐conjugated SF scaffold was confirmed by a 3‐(4,5‐dimethyltriazol‐2‐y1)‐2,5‐diphenyl tetrazolium assay. Thus, this study demonstrated that the biomimic properties of the scaffold could be enhanced by surface modification with SEP. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40138.     

Microstructure and creep resistance of a diffusionally aluminized Ni-base superalloy

An aluminide layer was formed on a wrought Ni-base superalloy by the diffusional aluminizing method, which involves a physical vapor deposition of Al followed by two-step heat treatment in vacuum. Microstructural analysis revealed the presence of an aluminide layer, inter-diffusion zone (IDZ), and affected substrate, all of which developed due to the inter-diffusion of deposited Al and elements in the matrix. In addition, a wide carbide free zone, in which grain boundaries were mostly denuded of carbides, was found below the IDZ. Depth profiling analysis using a glow discharge spectrometer confirmed the reduced carbon content in the carbide free zone. At 900 °C, the diffusionally aluminized specimens showed a decrease in creep-rupture life caused by the presence of the carbide free zone. Fracture surface and cross-section microstructure observation confirmed the detrimental effect of the carbide free zone on the creep resistance of the diffusionally aluminized Alloy 617.     

Fast agglomerative clustering using information of k-nearest neighbors

In this paper, we develop a method to lower the computational complexity of pairwise nearest neighbor (PNN) algorithm. Our approach determines a set of candidate clusters being updated after each cluster merge. If the updating process is required for some of these clusters, k-nearest neighbors are found for them. The number of distance calculations for our method is O(N²), where N is the number of data points. To further reduce the computational complexity of the proposed algorithm, some available fast search approaches are used. Compared to available approaches, our proposed algorithm can reduce the computing time and number of distance calculations significantly. Compared to FPNN, our method can reduce the computing time by a factor of about 26.8 for the data set from a real image. Compared with PMLFPNN, our approach can reduce the computing time by a factor of about 3.8 for the same data set.     

Influence of temperature on threshold stress for reorientation of hydrides and residual stress variation across thickness of Zr-2.5Nb alloy pressure tube

Threshold stress, σ_th, for reorientation of hydrides in cold worked and stress-relieved (CWSR) Zr-2.5Nb pressure tube material was determined in the temperature range of 523-673 K. Using tapered gage tensile specimen, mean value of σ_th was experimentally determined by two methods, half thickness method and area compensation method. The difference between local values of σ_th measured across the thickness of the tube and the mean σ_th values yielded the residual stress variation across the tube thickness. It was observed that both the mean threshold stress and residual stress decrease with increase in reorientation temperature. Also, the maximum value of residual stresses was observed near the midsection of the tube.     

Thermal capture of electrons and holes at zinc centers in silicon

The thermal capture rates of electrons and holes at zinc centers in silicon are obtained in reversed biased N⁺P and P⁺N diodes from junction capacitance transients due to capture of photogenerated and injected carriers. The electric field dependence of the thermal capture rates of holes at singly ionized zinc centers is E^?1·1, while that at doubly ionized zinc centers is exp(?E/E₀). The temperature dependence of the thermal capture rate of holes at doubly ionized zinc centers is small. The thermal capture rate of electrons at neutral zinc centers is 2·0×10^?9cm³/sec with very little field dependences, while that at singly ionized zinc centers is 5·0×10^?11cm³/sec with very little field and temperature dependence below 170°K. Auger-impact emission rate of electrons trapped at doubly ionized zinc centers by electrons is 3·5×10^?10cm³/sec with very little field and temperature dependence below 170°K.     

Interface edge effect and its contribution to the frequency dispersion of metal-oxide-semiconductor admittance

Room temperature frequency dispersion of the admittance of Metal-Oxide-Semiconductor (MOS) capacitors made on non-degenerate n-type silicon substrate with (111) surface orientation was studied. A simplified lumped equivalent circuit model which takes into account the interface edge effect, i.e. carrier generation-recombination-trapping via interface states near the edge of the surface inversion region, is proposed and found to be in good agreement with experimental data. Our model also suggests another method of calculating the density of interface states. Fundamental properties of interface states are estimated from experimental data. A self-consistency check is made among the values of equivalent circuit elements to substantiate our model.