Error probability for reduced-state sequence estimation

The performance of ideal reduced-state sequence estimation (RSSE) (without error propagation) is known as a good approximation to the performance of real RSSE. In the literature, the minimum distance of ideal RSSE has been employed for approximating the error probability of real RSSE. However, this approximation can be very poor, even though the system has a large signal-to-noise ratio. In this work, a union upper bound on the error probability for ideal RSSE is used to approximate the true error probability. This union bound provides a better approximation than the minimum distance. A new method based on a stack algorithm and a subset-error state diagram is proposed for calculating this union bound. The stack algorithm is employed because it provides a good tradeoff between computer memory and computing time     

Cost benefit of a cooling energy storage system

Since the air conditioner (A/C) load contributes 30% of the peak demand of Taiwan Power Company (Taipower) system during the summer season, load management by A/C load clipping has become one of the most important topics in the Taipower system. Since the eutectic salt is a complete inorganic compound with a freezing point of 47°F and latent heat of 41 Btu/lb, it is a good medium for an energy storage system. An A/C system with an 1800 RT-HR eutectic salt energy storage tank was built on the campus of the National Sun Yat-Sen University (NSYSU) for demonstrating the cooling energy storage (CES) system. By computer simulation, it is found that 41.1% of the electric peak demand has been reduced and 56% of the energy consumption has been shifted from peak hours to off-peak hours by the CES-system. In this paper, the mathematical model of the eutectic salt CES-system has been developed for computer simulation of the energy storage system. It is found that the optimal capacity of the storage tank is determined by the off-peak time period and the largest annual electricity charge saving could be obtained by applying the smallest nominal chiller size under the optimal operating conditions     

Numerical methods for second-order shape sensitivity analysis with applications to heat conduction problems

In this paper, two finite-element-based schemes for second-order shape sensitivity analysis are presented. In the first formulation, the AV-DD method, the first-order shape sensitivity equation is derived and expressed in terms of state and adjoint variables. The resultant equation is then directly differentiated to obtain the second-order shape sensitivity equation. In the second formulation, the DD-AV method, the functional of concern is differentiated twice to yield the second-order sensitivity equation in which the second-order shape derivatives can be eliminated by introducing a proper adjoint equation. A thermal fin problem and a thermal insulation layer problem have been studied to validate the proposed schemes. It is shown that both methods yield identical results, though the DD-AV method is computationally more efficient.     

The detection of sodium vapor bubble collapse in a liquid metal fast breeder reactor

Sodium boiling detection utilizing the sound pressure emanated during the collapse of a sodium vapor bubble in a subcooled media is discussed in terms of the sound characteristic, the reactor ambient noise background, transmission loss considerations and performance criteria. Data obtained in several loss of flow experiments on Fast Test Reactor Fuel Elements indicate that the collapse of the sodium vapor bubble depends on the presence of a subcooled structure or sodium. The collapse pressure pulse was observed in all cases to be on the order of a kPa, indicating a soft type of cavitational collapse. Spectral examination of the pulses indicates the response function of the test structure and geometry is important. The sodium boiling observed in these experiments was observed to occur at a low (<50°C) liquid superheat with the rate of occurrence of sodium vapor bubble collapse in the 3 to 30 Hz range. Reactor ambient noise data were found to be due to machinery induced vibrations, flow induced vibrations, and flow noise. These data were further found to be weakly stationary enhancing the possibility of acoustic surveillance of an operating Liquid Metal Fast Breeder Reactor. Based on these noise characteristics and extrapolating the noise measurements from the Fast Flux Test Facility Pump (FFTP), one would expect a signal to noise ratio of up to 20 dB in the absence of transmission loss. The requirement of a low false alarm probability is shown to necessitate post detection analysis of the collapse event sequence and the cross correlation with the second derivative of the neutronic boiling detection signal. Sodium boiling detection using the sounds emitted during sodium vapor bubble collapse are shown to be feasible but a need for in-reactor demonstration is necessary.     

The 4‐acetylantroquinonol B isolated from mycelium of Antrodia cinnamomea inhibits proliferation of hepatoma cells

BACKGROUND: Antrodia cinnamomea is known for its antihepatoma activity, yet the identity of its active compound was unclear. In this study, a 5‐ton fermenter was used to prepare sufficient mycelium of A. cinnamomea for active compound isolation and identification. RESULTS: Using antiproliferative activity toward HepG2 cells as guidance in the isolation process, 4‐acetylantroquinonol B was purified and identified to be the major bioactive compound of A. cinnamomea cultivated by submerged fermentation. The median effective doses (EC₅₀) of 4‐acetylantroquinonol B for HepG2 cells were 0.10 ± 0.00 and 0.08 ± 0.00 µg mL^?1 for 72 and 96 h treatments, respectively. The selective indices of 4‐acetylantroquinonol B were 100 and 125 for 72 and 96 h treatments, respectively, indicating that this compound had high selective activity for hepatoma cells. CONCLUSION: 4‐Acetylantroquinonol B is the major antihepatoma constituent of Antrodia cinnamomea mycelium produced by submerged fermentation. Copyright © 2010 Society of Chemical Industry     

Ethanolic extracts of Antrodia cinnamomea mycelia fermented at varied times and scales have differential effects on hepatoma cells and normal primary hepatocytes

Mycelia of Antrodia cinnamomea (AC), an edible fungus native to Taiwan, were produced by submerged fermentation with various fermentation times in 250 mL, 5 and 500 L fermentors and were evaluated for the effect of fermentation products on the viabilities of Hep3B and HepG2 hepatoma cells and normal primary rat hepatocytes. The results showed that the ethanolic extracts of AC mycelia (from 250 mL fermentation for 8 wk and 5 and 500 L fermentations for 4 wk) possessed high antihepatoma activity. The IC(50) of ethanolic extract of AC mycelia fermented for 8 wk in a 250 mL fermentor against Hep3B and HepG2 cells were 82.9 and 54.2 microg/mL, respectively. Furthermore, the IC(50) for Hep3B and HepG2, treated with ethanolic extract of AC mycelia fermented for 4 wk in the 5 L fermentor were 48.7 and 3.8 microg/mL, respectively. Those treated with ethanolic extract of AC mycelia fermented for 4 wk in the 500 L fermentor were 36.9 and 3.1 microg/mL, respectively. No adverse effects of all samples on normal primary rat hepatocytes were observed.     

An impulse-response extracting method from the modulated signal in a roller bearing

In this paper, a signal processing method is proposed to derive the impulse responses of the defect impacts for a roller bearing, and is carried out in two steps. First, the envelope detection for the vibration signal with amplitude modulation is implemented through the linear least square analysis under the assumption of a stepwise function for the envelope signal. Secondly, the signal processing of impulse-response enhancement is applied to eliminate the sidebands around the defect frequencies. The impulse responses of the defect impacts could be derived and the sidebands in the impulse-response spectrum could be theoretically eliminated. Accordingly, the spectrum would be helpful to apply in the bearing defect diagnosis, especially under the condition of non-uniform loading. From the theoretical analysis and the experimental studies, it is shown that the proposed signal processing method could effectively derive the impact responses of the defects impacts for a roller bearing system and the sidebands in the impulse-response spectrum could be reduced or even eliminated.     

Effects of post-annealing on electrical properties of CuF2·xH2O-doped KNN ceramics for rotary-linear ultrasonic motors

Lead-free (K_0.5Na_0.5)NbO₃ (KNN) ceramics were prepared using a novel sintering aid (CuF₂·xH₂O (x$\approx$2)) to investigate the effects of post-annealing temperature and atmosphere on oxygen vacancies, microstructure, and electrical properties. Post-annealing (K_0.5Na_0.5)NbO₃ +?1.5?mol% CuF₂·xH₂O (KNNCH) ceramics at 800?°C under argon was shown to increase the bulk relative density to 97% through the formation of a homogeneous microstructure with liquid phase. The resulting samples presented the following excellent piezoelectric properties: k_p：34.1% ($\pm \text{2\%}$); k_t：45.3% ($\pm \text{2\%}$); Q_m：3170 ($\pm \text{2\%}$); R_z：8.6?Ω ($\pm \text{3}\text{\%}$); and tan$\delta$：0.1%. Our results clearly demonstrate that annealing under argon can produce oxygen vacancies in ceramics, which has a significant influence on the stability of domain structures of the samples. Piezoelectric motors fabricated using these ceramics achieved a velocity of 4.5?mm/s, vertical velocity of 3.02?·mm/s, and output power of 2.93?mW with a negligible increase in temperature and high stability while driven.     

Synthesis, characterization and electrostatic dissipating ability of poly(oxyethylene) block polyesteramides

Poly(oxyethylene)diamines were included in the copolymerization of ethylene glycol and dicarboxylic acids, such as terephthalic, adipic and sebacic acid, to produce a series of hydrophilic polyether-ester-amides. With the addition of poly(oxyethylene)diamines (average molecular weight of 2,000) to PET in the amounts of 3.2, 6.6, 12 and 16 wt%, melting points of these polymers dropped accordingly, from 240 °C to around 227 °C, and the electronic resistivity decreased from 1×10¹³ to approximately 8×10⁸ ohm/sq. For comparison, the introduction of hydrophilic PEG-2000 or a low molecular weight diamine, such as triethyleneglycol diamine, has less effect on electronic resistivity. Molecular weight, polymer rigidity and ageing are other factors affecting the surface resistivity. The degree of hydrophilicity was measured by the moisture absorption of the fibers made from these polyether-ester-amides. A weight gain of 0.96% was observed for 12 wt% poly(oxyethylene)diamine modified polyether-ester-amides in comparison with 0.40% for the unmodified polyethylene terephthalate). These results are explained by a mechanism involving moisture absorption on the polymer surface through the formation of hydrogen bonding with amide and-(OCH₂CH₂)-functionalities on the polymer surface.