Sliding‐mode control of a three‐degrees‐of‐freedom nanopositioner

This paper presents the sliding‐mode control of a three‐degrees‐of‐freedom nanopositioner (Z, θ_x, θ_y). This nanopositioner is actuated by piezoelectric actuators. Capacitive gap sensors are used for position feedback. In order to design the feedback controller, the open‐loop characteristics of this nanopositioner are investigated. Based on the results of the investigation, each pair of piezoelectric actuators and corresponding gap sensors is treated as an independent system and modeled as a first‐order linear model coupled with hysteresis. When the model is identified and the hysteresis nonlinearity is linearized, a linear system model with uncertainty is used to design the controller. When designing the controller, the sliding‐mode disturbance (uncertainty) estimation and compensation scheme is used. The structure of the proposed controller is similar to that of a proportional integral derivative controller. Thus, it can be easily implemented. Experimental results show that 3‐nm tracking resolution can be obtained. Copyright © 2008 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

Channel capacity in time sharing multiple-access flat fadingchannels employing variable rate M-QAM transmitter

An approach for obtaining channel capacity when rate adaptive transmitters with co-ordination among all users are time sharing flat fading channels for transmission is presented. This channel capacity is obtained when only the mobile that observes the best channel condition is assigned to transmit at any time. Channel capacity in general gamma fading channels is computed     

Low Complexity Antenna Selection Scheme for Multicarrier MIMO Broadcast Communication

A low complexity antenna selection scheme for multicarrier MIMO (Multiple Input Multiple Output) broadcast systems is proposed in this paper. Under special condition of single user in the system or when the number of subcarrier is only one, the system reduces to conventional MIMO-OFDM (Orthogonal Frequency Division Multiplexing) system or MIMO-BC (Broadcast Channel) system respectively. By analysing sub-optimal antenna selection schemes developed earlier for single user MIMO-OFDM systems and single carrier MIMO-BC systems, one can see many similarities which can be extended to multicarrier MIMO broadcast systems. The proposed method exploits these similarities to obtain a low complexity system design with acceptable performance. The performance of the proposed scheme is studied via extensive simulation, and the computational complexity involved is compared to the conventional scheme. A selection gain of approximately 0.5 b/s/Hz is shown to be achievable using only two out of three antennas, and the proposed scheme is able to achieve up to 90% of the gain. This is achieved at a complexity that is significantly lower than the conventional methods, hence the practical implementation of the proposed scheme can be justified.     

Effect of the combination of various NaCl levels and soy protein isolate on the quality characteristics of smoked pork loins

The objectives of this study were to evaluate the physicochemical, textural and sensory properties of smoked pork loins (PL) containing various levels of NaCl (0.0–2.0%) alone or in combination with soy protein isolates (SPI; 1.0%). The pH values, moisture, fat, and protein contents (%) of smoked PL were 5.97–6.17, 63.3–69.1%, 2.64–4.26%, and 20.2–26.6%, respectively. Increased NaCl levels increased moisture contents (%) and sensory scores, as well as reduced Hunter redness and yellowness and cooking loss (CL, %) (P < 0.05). A NaCl level of 1.0% had resulted in a CL (%) level similar to those at regular‐salt levels (1.5% and 2.0% NaCl). When 1.0% SPI was incorporated with smoked PL, the NaCl level of 0.5% was also similar to the CL (%) at higher NaCl levels and improved sensory scores. Thus, a NaCl level of at least 1.0% was required for the manufacture of smoked PL; however, smoked PL could be manufactured with 0.5% salt when 1.0% SPI was included as part of the manufacture of smoked PL to effect quality characteristics similar to those achieved with regular‐salt (1.5% and 2.0% NaCl) smoked PL.     

Designation of a GLP facility by the Korean Ministry of Environment GLP authority: the case of the Center for Occupational Toxicology.

In this report, the process of designating a GLP facility by the Korean Ministry of Environment (MOE) is described in detail using the case of the Center of Occupational Toxicology (COT). The COT, which had been prepared as a GLP facility, filed an application to the National Institute of Environmental Research (NIER) of the MOE. The GLP system of the COT was evaluated by a harmonized evaluation team that consisted of several authorities including the NIER, the National Institute of Agricultural Science and Technology (NIAST), and the National Institute of Toxicological Research (NITR). The evaluation was arranged for mutual acceptance of data among GLP authorities. The designation process, additional documents necessary for applying GLP facility, the process of test facility evaluation including reviewing the application and site inspection, and inspection results and submission of correction plans are explained by using the instance of the inspection process of the COT. COT was evaluated as a suitable GLP facility for acute oral and inhalation toxicity tests and the Ames test.     

Synthesis and properties of poly(ether imide)s derived from 2,5‐bis(3,4‐dicarboxyphenoxy)biphenyl dianhydride and aromatic ether–diamines

A series of poly(ether imide)s (PEIs) with light colors and good mechanical properties were synthesized from 2,5‐bis(3,4‐dicarboxyphenoxy)biphenyl dianhydride and various aromatic ether–diamines via a conventional two‐step polymerization technique that included ring‐opening polyaddition at room temperature to poly(amic acid)s (PAAs) followed by thermal imidization. The precursor PAAs had inherent viscosities ranging from 0.71 to 1.19 dL/g and were solution‐cast and thermally cyclodehydrated to flexible and tough PEI films. All of the PEI films were essentially colorless, with ultraviolet–visible absorption cutoff wavelengths between 377 and 385 nm and yellowness index values ranging from 10.5 to 19.9. These PEIs showed high thermal stabilities with glass‐transition temperatures of 206–262°C and decomposition temperatures (at 10% weight loss) higher than 478°C. They also showed low dielectric constants of 3.39–3.72 (at 1 MHz) and low water absorptions below 0.85 wt %. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Recurrent nasal tumor detection by dynamic MRI

The purpose of this research is to detect and enhance the recurrent nasal tumor region by computing the relative intensity difference between consecutive MR images after using a contrast agent. In this article, we apply a relative signal increase model to recognize a recurrent nasal tumor by dynamic MR images. A robust estimation technique is used to deal with matching corresponding points among different images. The active contour technique is applied to refine automatically the region of interest and obtain a more precise definition of the area of interest. The quantitative evaluation of dynamic MR data is modeled by fitting three-parameter time-intensity curves     

Carbon molecular sieve membranes derived from pseudo-interpenetrating polymer networks for gas separation and carbon capture

The design of polyimide-based pseudo-interpenetrating polymer networks (IPNs) is proposed to tailor the molecular structure of polymeric precursors for fabricating carbon molecular sieve membranes (CMSMs). To demonstrate the feasibility of this concept, pseudo-IPNs comprising of poly(2,3,5,6-phenylene-2,2′-bis(3,4-carboxylphenyl)hexafluoropropane) diimide (6FDA–TMPDA) and 2,6-bis(4-azidobenzylidene)-4-methylcyclohexanone (azide) are used to fabricate CMSMs. The gas transport properties of CMSMs are dependent on the azide loading and heat treatment temperature. During the pyrolysis, two competing processes of pore evolution from the released gases and molecular transformation are occurring simultaneously. The creation of pores determines the structural morphology of the CMSM at a low pyrolysis temperature of 550 °C while the molecular rearrangement is the governing factor for carbonization at an elevated temperature of 800 °C. The CMSMs prepared at 550 °C display good CO₂/N₂ separation performance. The 6FDA–TMPDA/azide (90–10) CMSM pyrolyzed at 550 °C shows a CO₂ permeability of 9290 ± 170 Barrer and an ideal CO₂/N₂ selectivity of 26.0 ± 0.8. CMSMs with high CO₂/CH₄ selectivity can be fabricated by carbonization at 800 °C. The 6FDA–TMPDA/azide (70–30) CMSM prepared at 800 °C has a CO₂ permeability of 280 ± 7.0 Barrer and CO₂/CH₄ selectivity of 164 ± 6.0. The CMSMs derived from polyimide/azide pseudo-IPNs exhibit potential use in pre- and post-combustion CO₂ capture.     

Effects of Ni Additions on the Growth of Cu<Subscript>3</Subscript>Sn in High-Lead Solders

In reactions between solders and Cu, additions of minor alloying elements, such as Fe, Co or Ni, to solders often reduce the Cu₃Sn growth rate. Nevertheless, the mechanism for this effect remains unresolved. To provide more experimental observations that are essential for uncovering this mechanism, growth of Cu₃Sn in the reaction between Cu and high-lead solders with or without Ni additions has been studied. The solders used for this study were 10Sn-90Pb and 5Sn-95Pb doped with 0 wt.%, 0.03 wt.%, 0.06 wt.%, 0.1 wt.% or 0.2 wt.% Ni. Reaction conditions included one reflow at 350°C for 2 min and solid-state aging at 160°C for up to 2000 h. The effect of Ni on the growth of Cu₃Sn is discussed in detail based on the experimental results.