Application of the transmission line equivalent circuit model to the analysis of the PN junction admittance under d.c. bias

Exact non-equilibrium one-energy-level numerical solutions of the admittance of a p+n junction are obtained from the nonuniform transmission line equivalent circuit model. Capacitance and conductance curves for equilibrium and reverse-biased gold-doped silicon diode are calculated using experimental values of emission and capture rates. Comparisons between theoretical and experimental frequency dependences of the admittance using new experimental capture rates show good agreements over a wide range of reverse bias.     

Epitaxy-Like Protective Layers for High-Performance Low-Cost Au/Pd/Ni Preplated Cu Alloy Leadframes

In this paper, we report the performance, the crystal microstructure, and defects of Au/Pd/Ni/Cu preplated lead frames (PPF). The wire pull test, the solderability test, and high-resolution transmission electron microscopy (HRTEM) are employed to characterize the PPFs in order to understand the relationship between performance and microstructure. The electroplated PPFs are composed of Au (3 nm)/Pd (5 to 15 nm)/Ni (0.7 mum)/Cu substrate. We optimize the electroplating profile and determine the minimum thickness of the Pd layer with the PPF performance satisfying the industry standards. Further increasing the Pd layer thickness beyond the critical thickness will not enhance the performance more, but increase the product cost. With the optimized electroplating profile, the electroplated Au layer is epitaxially deposited on the Pd layer, and so does the Pd layer on the Ni layer. The interface between the Au and Pd layers is in general coherent in spite of the about 4.8% mismatch strain between the Au and Pd lattices because the Au layer thickness is only 3 nm small. Misfit dislocations and nanotwins are present at the interface between the Pd and Ni layers, which are generated to release the about 10.4% misfit strain between the Pd and Ni lattices     

A two-stage algorithm for MIMO blind deconvolution of nonstationarycolored signals

A new two-stage algorithm is proposed for the deconvolution of multi-input multi-output (MIMO) systems with colored input signals. While many blind deconvolution algorithms in the literature utilize high order statistics of the output signal for white input signals, the additional information contained in colored input signals allows the design of second-order statistical algorithms. In fact, practical signal sources such as speech signals do have distinct, nonstationary, colored power spectral densities. We present a two-stage signal separation approach in which the first step utilizes a matrix pencil between output auto-correlation matrices at different delays, whereas the second stage adopts a subspace method to identify and deconvolve MIMO systems     

A web search-centric approach to recommender systems with URLs as minimal user contexts

In service-oriented computing, a recommender system can be wrapped as a web service with machine-readable interface. However, owing to the cross-organizational privacy issue, the internal dataset of an organization is seldom exposed to external services. In this paper, we propose a higher level recommender strategy INSERT that guides the underlying external universal recommender to suggest a set of indexes. INSERT then matches the title of each top-ranked index entry with the domain-specific keywords in the organization's internal dataset, and further directs the universal recommender to verify the popularity of such matching. INSERT finally makes recommendation based on the verification results. INSERT also employs URLs taken from a client as user contexts, which is challenging because URLs contain little content. Our experiment shows that this strategy is feasible and effective.     

Understanding granular mixing to enhance coating performance in a pan coater: Experiments and simulations

The knowledge of the particle flow and mixing in a pan coater is critical to optimize the design and operation of coating equipment. Mixing is an important but poorly understood aspect of coating of pharmaceutical dosage forms (tablets). Our study focuses on the fundamental mechanisms of granular flow and mixing and their relationship to the coating performance. A quantitative method is developed and validated to characterize the mixing process throughout the mixing vessel. This method is used to establish a baseline determination of mixing homogeneity as a function of various mixing conditions. White and red non-pareils of 5–6 mesh size are loaded in the ellipsoid pan coater to check the effect of initial loading (side–side and front–back), fill level, orientation of the vessel and the vessel speed on granular mixing. Video-imaging and discrete-pocket samplers are used to quantify mixing and to finally estimate the optimal operating conditions. DEM (Discrete Element Method) based numerical model was also developed to study the effect of granular mixing in a pan coater. When the axis of rotation of the mixer is horizontal (no tilt), slower axial dispersion is observed in both the experiments and simulations, than the radial convection. However, tilt enhances axial mixing, and faster axial mixing is seen for higher tilt angles from the horizontal. The speed of the rotating vessel has a nominal effect on the rate of mixing in a coating pan, as observed from the experimental and simulation studies. Moreover, fill level has no significant effect on the rate of mixing. Coating experiments are performed in the pan coater where white non-pareils being coated by spraying Opadry II solution. DEM simulation of coating is performed with post processing particle dynamics data. The effects of various operational and spray parameters are determined on the coating performance. Optimal coating performance is attained at an optimal mixing condition.     

Physical parameters effect on ozone-initiated formation of indoor secondary organic aerosols with emissions from cleaning products

The effect of air exchange rate (ACH), temperature (T), and relative humidity (RH) on the formation of indoor secondary organic aerosols (SOAs) through ozonolysis of biogenic organic compounds (BVOCs) emitted from floor cleaner was investigated in this study. The total particle count (with D(p) of 6-225 nm) was up to 1.2 × 10(3)#cm(-3) with ACH of 1.08 h(-1), and it became much more significant with ACH of 0.36 h(-1) (1.1 × 10(4)#cm(-3)). This suggests that a higher ventilation rate can effectively dilute indoor BVOCs, resulting in a less ultrafine particle formation. The total particle count increased when temperature changed from 15 to 23 °C but it decreased when the temperature further increased to 30 °C. It could be explained that high temperature restrained the condensation of formed semi-volatile compounds resulting in low yields of SOAs. When the RH was at 50% and 80%, SOA formation (1.1-1.2 × 10(4)#cm(-3)) was the more efficient compared with that at RH of 30% (5.9 × 10(3)#cm(-3)), suggesting higher RH facilitating the initial nucleation processes. Oxidation generated secondary carbonyl compounds were also quantified. Acetone was the most abundant carbonyl compound. The formation mechanisms of formaldehyde and acetone were proposed.     

Influence of the Electron Deficient Co‐Monomer on the Optoelectronic Properties and Photovoltaic Performance of Dithienogermole‐based Co‐Polymers

A series of donor–acceptor (D–A) conjugated polymers utilizing 4,4‐bis(2‐ethylhexyl)‐4H‐germolo[3,2‐b:4,5‐b′]dithiophene ( DTG ) as the electron rich unit and three electron withdrawing units of varying strength, namely 2‐octyl‐2H‐benzo[d][1,2,3]triazole ( BTz ), 5,6‐difluorobenzo[c][1,2,5]thiadiazole ( DFBT ) and [1,2,5]thiadiazolo[3,4‐c]pyridine ( PT ) are reported. It is demonstrated how the choice of the acceptor unit ( BTz , DFBT , PT ) influences the relative positions of the energy levels, the intramolecular transition energy (ICT), the optical band gap (E_g^opt), and the structural conformation of the DTG ‐based co‐polymers. Moreover, the photovoltaic performance of poly[(4,4‐bis(2‐ethylhexyl)‐4H‐germolo[3,2‐b:4,5‐b′]dithiophen‐2‐yl)‐([1,2,5]thiadiazolo[3,4‐c]pyridine)] ( PDTG‐PT ), poly[(4,4‐bis(2‐ethylhexyl)‐4H‐germolo[3,2‐b:4,5‐b′]dithiophen‐2‐yl)‐(2‐octyl‐2H‐benzo[d][1,2,3]triazole)] ( PDTG‐BTz ), and poly[(4,4‐bis(2‐ethylhexyl)‐4H‐germolo[3,2‐b:4,5‐b′]dithiophen‐2‐yl)‐(5,6‐difluorobenzo[c][1,2,5]thiadiazole)] ( PDTG‐DFBT ) is studied in blends with [6,6]‐phenyl‐C₇₀‐butyric acid methyl ester ( PC₇₀BM ). The highest power conversion efficiency (PCE) is obtained by PDTG‐PT (5.2%) in normal architecture. The PCE of PDTG‐PT is further improved to 6.6% when the device architecture is modified from normal to inverted. Therefore, PDTG‐PT is an ideal candidate for application in tandem solar cells configuration due to its high efficiency at very low band gaps (E_g^opt = 1.32 eV). Finally, the 6.6% PCE is the highest reported for all the co‐polymers containing bridged bithiophenes with 5‐member fused rings in the central core and possessing an E_g^opt below 1.4 eV.     

Edge Computing-Based Joint Client Selection and Networking Scheme for Federated Learning in Vehicular IoT

In order to support advanced vehicular Internet-of-Things(IoT)applications,information ex-changes among different vehicles are required to find efficient soluti...     

Nanocomposite of chitosan and silver oxide and its antibacterial property

An aqueous emulsion of chitosan nanoparticles encapsulating silver oxide is prepared from silver nitrate and chitosan. The nanoparticles are positively charged with an average diameter of 300 nm. The dried particle has a spherical shape with a 100 nm diameter. The emulsion is applied onto cotton and delivers a durable antibacterial activity against S. aureus and E. coli, after 20 washings. The coefficient of friction of the treated fabric is similar to that of the untreated cotton fabric. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

The free-radically prepared copolymers of acrylonitrile with furfuryl alcohol and similar furan derivatives

The preparation of copolymers of acrylonitrile with furfuryl alcohol, furfuryl acetate, bis-2,5-hydroxymethyl furan and bis-2,5-acetoxymethyl furan by a free radical reaction is described. Proton and ¹³C-n.m.r. spectroscopy has been used to characterise the residues that form from the furan monomers by the addition reaction. The residues produced by a 5,4-addition to the furfuryl alcohol ring or by 2,3-addition to the 2,5-dihydroxyfuran ring are susceptible to acid and undergo a rearrangement which removes the olefinic structure. The copolymers are decomposed to a hard, glassy carbonaceous material by heating in nitrogen in a process that has been examined by thermogravimetric analysis and elemental analysis. The copolymers prepared from furan monomers that contain a methylol group decompose more readily at a lower temperature than those which lack the group or than those in which the alcohol has been acetylated.