Fast segmentation of porcelain images based on texture features

This study aims to segment objects within images of porcelain artifacts to help users retrieve the images in an efficient and convenient manner. Through digital archiving, a tremendous number of porcelain images have been created. To avoid interference due to the image’s background during the retrieval process, it is necessary to segment objects in advance to accommodate high-precision image retrieval. In the proposed segmentation process, four texture features, including coarseness, contrast, directionality, and gradient, are first obtained. The morphological processing, which involves PCA (principal component analysis), Otsu’s method, and object filter for opening and closing operation, is applied. Finally, regarding the objects selected by object filter, boundary extraction and watershed segmentation are performed to segment the porcelain objects from the background. In our image segmentation experiment using images of Chinese porcelain from various dynasties, featuring various shapes and colors, complete and accurate segmentation results are produced. The results can be used as a reference for future identification of the era to which the artifacts belong, and also to lay a foundation for future development of porcelain image retrieval techniques as a benefit to academic research.     

Study of start-up vibration response for oil whirl, oil whip and dry whip

Oil whip induces self-excited vibration in fluid-handling machines and causes self-excited reverse precessional full annular rub, known as “dry whip”, which is a secondary phenomenon resulting from a primary cause, that is, “coexistence of oil whip and dry whip”. For predicting these instabilities, the clues are hidden in start-up vibration signals of these kinds of machines. This paper presents a method for predicting these kinds of instabilities. First, a Hilbert spectrum combining a full spectrum, which is named the “full Hilbert spectrum”, is developed to reveal the whole process. Next, the transient position of a shaft centerline combining an acceptance region is introduced to predict instability at an early stage. The results presented in this study amply demonstrate the transition from stability to instability and the behavior of fluid-induced instability and rub in rotor systems. By this finding, bearing designers can completely understand these instability phenomena existing in fluid-handling machines. As a result, the control parameter for designing controllable bearings can be obtained and the instability problems can be resolved. Consequently, these findings are worth noting.     

Simulation of electrical characteristics of InP double-heterojunction bipolar transistors with InGaAsSb base

We study the effect of antimony (Sb) content in the InGaAsSb base layer of InP double-heterojunction bipolar transistors (DHBTs), under the condition of lattice match, by using a two-dimensional device simulator Medici. Careful calibration of physical parameters is first done to ensure that the simulation result matches data measured from a reference device. When the composition of Sb in the InGaAsSb base region is varied, the conduction band offset (ΔE_C), effective density of states in conduction band and valence band (N_C, N_V), bandgap energy (E_G), and intrinsic carrier concentration (n_i) are changed accordingly. These semiconductor material parameters are considered in the simulation to compare the electrical characteristics of the DHBT. In addition to the Sb composition, different materials of In_0.52Al_0.48As or InP in the emitter are simulated. The study on Sb content in the base and the heterostructure of E-B junction helps the development and optimization of InGaAsSb DHBTs.     

Synthesis of poly(3,7-N-alkylphenothiazinyl methylene)

Summary Polymers containing phenothiazine nuclei in the main chain were prepared by the reactions of a seriese of N-alkylphenothiazines with formaldehyde under acid conditions in dioxane. In the case of lower alkyl groups such as methyl or ethyl, significant amounts of gel accompanied the resulting polymers. ¹³C-NMR spectroscopy established the chemical structures of the polymers and UV spectroscopic studies indicated -electron interaction due to homoconjugation between neighboring phenothiazine nuclei. The polymers were readily oxidized to give colored products by photoirradiations in CHCl₃.     

Temperature-dependent memory characteristics of silicon-oxide-nitride-oxide-silicon thin-film-transistors

This study investigates the temperature-dependent memory characteristics of polycrystalline silicon thin-film transistors with oxide/nitride/oxide stack gate dielectrics and N⁺ poly-Si gate structures for nonvolatile memory application. As the device was programmed by Fowler-Nordheim tunneling at high temperature, some electrons captured in shallow traps could obtain enough thermal energy to de-trap to the gate, resulting in low programming efficiency. As the programming time increases, the hole injection through the blocking oxide from the gate would further lead the threshold voltage to decrease. In addition, the retention characteristic of the device programmed at higher temperature exhibits better charge storage ability. Because the electrons trapped in the shallow traps of the nitride layer can be easily de-trapped when temperature rises, the memory characteristics are mainly dominated by charges stored in the deep traps.     

Efficient multilayer red fluorescent polymer light-emitting diodes by host and guest blend system

Efficient red light polymer light-emitting diodes are obtained by energy transfer from host and guest blend system. Two kinds of blend systems, SPB02:(10-(2-benzothiazolyl)-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-[1] benzopyrano [6,7,8-ij]quinolizin-11-one)(C545T):4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) and SuperYellow (SY):poly(3,3^′′′-didodecylquaterthiophene) (PQT-12), are used as the active layers. C545T is a green emitter, acting as an assistant dopant to improve the energy transfer from blue SPB02 host to red DCJTB. The efficiency can achieve to 3.3 cd/A for DCJTB and 3.5 cd/A for PQT-12 system by multilayer device structure with 2,2,2^′′-(1,3,5-phenylene)-tris(1-phenyl-1H-benzimidazole) (TPBi) as electron transport layer. The SuperYellow:PQT-12 device shows great luminance of 16,930 cd/m².     

Numerical investigation on thermofluid fields induced by pen-like atmospheric non-thermal plasma torch with array type: A preliminary study

The pen-like plasma torch device, which was developed in 2002, has very simple structure and has been successfully applied for the surface treatment to improve hydrophilic properties of plastic film and polyethylene. However, due to the effective treating area of a single pen-like atmospheric plasma torch is still very limited, the current status of the device is still far from the practical applications. In view of this, the development of the new design of the “pen-like atmospheric plasma torch array”, which is composed of multiple pen-like atmospheric plasma torches, is undergoing. It is expected the array design of the plasma-torch system could increase the effective treating area and satisfy the need of practical applications. The present paper carried out the numerical simulations of the thermofluid fields induced by the devices with dual and four pen-like plasma torches. The major interest is to exploit the different flow features of single-, dual- and four-plasma torch system. The results revealed in the present study provide fundamental understanding of the thermofluid fields induced by the multiple pen-like plasma torches, which are worthwhile for the design work of the array-type devices.     

10 GHz dual-conversion low-IF downconverter with microwave and analogue quadrature generators

A 10 GHz dual-conversion low-IF downconverter using 0.18-mum CMOS technology is demonstrated. The high-frequency quadrature RF and LO₁ signals are generated by broadside-coupled quadrature couplers while a two-section polyphase filter is utilised for the low-frequency LO₂ quadrature signal generation. As a result, the demonstrated downconverter achieves a conversion gain of 7 dB, IP_{1 dB} of -16 dBm, IIP₃ of -5 dBm and noise figure of 26 dB at a 1.8 V supply. The image-rejection ratio of the first/second image signal is 33/42 dB for IF frequency ranging from 10 to 60 MHz, respectively.     

Broadband SiGe HBT Gilbert downconverter with 1.8 to 36 GHz integrated dual Marchand balun

A broadband Gilbert downconverter with an integrated dual Marchand balun (balanced to unbalanced transformer) is demonstrated by using 0.35 m SiGe heterojunction bipolar transistor (HBT) technology. A dual Marchand balun consisting of a lower band balun and an upper band balun is employed in the LO stage of the downconverter to maintain balanced LO signals from 1.8 to 36 GHz. The broadband downconverter has peak conversion gain of 3 dB at RF 3 GHz and 3 dB bandwidth of 1.8 to 20 GHz at 3.3 V DC supply.     

A numerical approach of conjugate hydrogen permeation and polarization in a Pd membrane tube

A numerical method accounting for conjugate hydrogen permeation in a dense palladium (Pd) membrane tube is developed. In the method, hydrogen permeation across the membrane is treated by introducing a source–sink pair and a gas mixture produced from water gas shift reactions serves as the feed gas of the membrane tube. The influences of flow patterns of feed gas and sweep gas as well as their flow rates on hydrogen separation are investigated. A concentration polarization index (CPI) is also conducted to indicate the extent of polarization along the membrane surface. The predicted results suggest that counter-current modes are able to give the better performance of hydrogen separation compared to co-current modes, and hydrogen can be completely recovered if the flow rate of feed gas is low to a certain extent. However, lower flow rates of feed gas and sweep gas will trigger serious concentration polarization. With counter-current modes, the feed gas sent into the membrane tube from the lumen side or the shell side is flexible. The optimum Reynolds number of sweep gas in accordance with the Reynolds number of feed gas is correlated by an arctangent function. This provides a useful reference for the operation of hydrogen separation by controlling sweep gas.