Hardware-In-The-Loop Simulations of Hole/Crack Identification in a Composite Plate.

The technology of hardware-in-the-loop simulations (HILS) plays an important role in the design of complex systems, for example, the structural health monitoring (SHM) of aircrafts. Due to the high performance of personal computers, HILS can provide practical solutions to many problems in engineering and sciences, especially in the huge systems, giant dams for civil engineering, and aircraft system. This study addresses the HILS in hole/crack identification in composite laminates. The multiple loading modes method is used for hole/crack identification. The signals of strains measured from the data-acquisition (DAQ) devices are accomplished by the graphical software LabVIEW. The results represent the actual responses of multiple loading mode tests of real specimens. A personal computer is employed to execute the identification work according to the strain data from DAQ devices by using a nonlinear optimization approach. When all the criteria are satisfied, the final identification results will be obtained. HILS will achieve real time identification of hole/crack in the composite plate by using the actual response measured from the sensors. Not only the size, but also the location and orientation of the crack/hole in a composite plate are successfully identified herein.

A variable-temperature scanning tunneling microscope operated in a continuous flow cryostat.

We present a continuous flow cryostat scanning tunneling microscope (STM) which can be operated at temperatures between 4.9 K and 300 K. A variable temperature insert with 20 mm aperture is installed in the cryostat. A base temperature of 4.9 K at the STM head was achieved with helium exchange gas cooling. By using a novel design of zirconia structure, the size of the STM head was minimized to 9.2 mm in outer diameter. The high compactness and rigidity of the STM head make it less sensitive to vibrations, contributing to the high stability of the tip-sample junction. The drifting rates of the STM at 4.9 K in the X-Y plane and Z direction are 1.96 and 3.05 pm/min, respectively. The performance of the STM was demonstrated by atomically resolved imaging of graphite and NbSe2 without using external vibrational isolation. Furthermore, the dI/dV spectra of NbSe2 were resolved near its critical temperature, illustrating the formation process of the superconducting gap as a function of temperature. This STM is ultrahigh vacuum and strong magnetic field compatible, making it promising for direct application in the extreme conditions involving water-cooled magnets and hybrid magnets.

A multi-tone active noise control system with a simplified local on-line secondary-path modeling.

Multi-tone active noise control (multi-tone ANC) technology has been widely studied to reduce the tonal noise with low frequencies. In the case of an ANC system with a time-varying secondary path, an on-line modeling method is necessary. In this work, a multi-tone ANC system with a simplified local on-line secondary-path modeling method is presented. A two-tone signal with small amplitude is added at the sideband of each noise tone to conduct the local modeling. The least mean square algorithm is used as the modeling algorithm which provides tracking for a time-varying secondary path. Notch filters and bandpass filters are adopted to separate the primary tones and the additive tones. Simulations and experimental results show that the proposed algorithm has good performance.

[Effect of behavioral training on learning and memory capacity and changes of hippocampal NR2B and GluR1 expressions in FGR offspring rats].

OBJECTIVE: To study the effect of behavioral training on the learning and memory abilities and changes of NR2B and GluR1 expressions in the hippocampus of offspring rats with fetal growth retardation (FGR). METHODS: A FGR model was established in SD rats by passive smoking. The offspring rats were divided into FGR group and control group, each then randomized into training and untrained group. Morris water maze behavioral training was carried out in postnatal months 2 and 4, and the learning and memory abilities of the young rats were assessed using dark-avoidance test and step-down test. NR2B and GluR1 expression in the hippocampus of the rats were detected by immunohistochemistry. RESULTS: In the dark-avoidance and step-down tests, the FGR rats showed deteriorated learning and memory performance in comparison with the control group, but behavioral training resulted in improved performance of the rats. The performance in FGR group was much improved after behavioral training, and the model factor and the training factor showed a significant interaction (P<0.05). The expression of NR2B and GluR1 in CA1 and CA3 regions of the hippocampus decreased in FGR group, then the their expressions in the CA1 region increased after training in both FGR and control groups, and the increment was especially obvious in GluR1 expression in the CA1 region at postnatal month 2. The two factors showed a significant interaction (P<0.05). CONCLUSION: Behavioral training can improve the learning and memory abilities of FGR offspring rats, the mechanism of which is probably related to increased expression of NR2B and GluR1 in the CA1 region of the hippocampus.

[Impact of fetal growth restriction on spatial learning and memory abilities of the offspring of rats].

OBJECTIVE: To test the impact of fetal growth restriction (FGR) on the spatial learning and memory abilities of the offspring of rats. METHODS: FGR Model of Sprague-Dawley rats was constructed according to the method of passive smoking. The offspring of the rats were divided into male FGR group, male control group, female FGR group and female control group. Within each group, the rats were randomly divided into three subgroups to be tested at 1, 2, and 4 months of age, respectively (n =10 for each subgroup). Morris water maze task was performed to assess the spatial learning and memory abilities of the rats. RESULTS: The escape latencies to find the platform were shortened with increased training times for all of the rats. At the age of 1 and 2 months, both male and female rats in the FGR group spent more time in finding the platform than their counterparts in the control group (P < 0.05). At the age of 4 months, significant prolonged latency was only found in the female rats. The rats in the FGR group, except the 4 months old male rats, were more likely to use non-effective strategies (random or marginal strategies) to find the platform than the efficient strategies (tendency or straight strategies). The rats in the FGR group stayed in the platform shorter than those in the control groups (P < 0.05). CONCLUSION: FGR can cause gender- and age-specific impairment of spatial learning and memory abilities to the offspring.

Mutagenizing brewing yeast strain for improving fermentation property of beer.

A brewing yeast mutant with perfect sugar fermentation capacity was isolated by mutagenizing the Saccharomyces pastorianus transformant, which carries an integrated glucoamylase gene and has one copy of non-functional alpha-acetolactate synthase gene. The mutant was able to utilize maltotriose efficiently, and the maltotriose fermentability in YNB-2% maltotriose medium increased from 32.4% to 72.0% after 5 d in shaking culture. The wort fermentation test confirmed that the sugar fermentation property of the mutant was greatly improved, while its brewing performances were analogous to that of the wild-type strain and the characteristic trait of shortened beer maturation period was retained. Therefore, we believe that the brewing yeast mutant would benefit the beer industry and would be useful for low caloric beer production.