激光超声无损检测技术研究

阐述了激光超声技术的产生机理,重点介绍了激光超声的热弹效应,探讨了激光超声检测技术的检测系统及其在工业发展中的应用前景,并对其激发原理进行了研究。     

芬顿与活性炭协同处理含酚废水的试验研究

对芬顿试剂和活性炭协同处理含酚废水的处理效果进行了研究,主要考察了过氧化氢的投加量、硫酸亚铁的投加量、pH值、吸附时间以及吸附温度等对处理效率的影响。试验结果表明,最佳处理条件是过氧化氢(30%)的投加量为2mL/L,硫酸亚铁的投加量为2g/L,pH值为5,吸附时间为30m in,吸附温度为30℃,此时COD去除率为86.82%,色度去除率为68.59%,SS去除率为64.31%。     

Effect of intermittent aeration on the treatment performance in a submerged membrane bioreactor

In order to improve removal for nitrogen in a pilot-scale submerged membrane bioreactor (SMBR), intermittent aeration was conducted, and the effect on the treatment performance under four kinds of operation condition (run 1, continuous aeration; run 2, 60/60 min aeration on/off time; run 3, 60/90 min aeration on/off time; run 4, 60/75 min aeration on/off time) was evaluated. The results showed that depending on the specific on/off of the aeration time ratio, removal efficiency of nitrogen could be improved significantly, and the removal rates of total nitrogen (TN) under different operation conditions were 28.0%, 59.5%, 66.8% and 70.7%, respectively. There were no obvious differences for removal rates for COD_Cr and ammonia among different operation conditions. In general, intermittent aeration could be used as a feasible way to improve treatment performance for nitrogen in the SMBR.     

Multi-target track-correlation algorithm of the graph-matching-based sensor network

For the problem of track correlation failure under the influence of sensor system deviation in wireless sensor networks, a new track correlation method which is based on relative positional relation chart matching is proposed. This method approximately simulates the track correlation determination process using artificial data, and integrally matches the relative position relation between multiple targets in the common measuring space of various sensors in order to fulfill the purpose of multi-target track correlation. The simulation results show that this method has high correlation accuracy and robustness.     

Phase field simulation of the 180° domain-switching process in PbTiO<Subscript>3</Subscript> single crystal under an antiparallel electric field

The process of 180° domain switching in PbTiO₃ single crystal under an antiparallel electric field was investigated by the three-dimensional phase field simulation, especially the effect of electric field on the type and duration of domain switching. It is found that the polarization reversal of domains takes place under an antiparallel electric field in PbTiO₃ single crystal. The results of the phase field simulation indicate that there is only 90° domain switching under a weak electric field. With the rise of the electric field, 180° domain switching appears. If the electric field is strengthened further, 90° domain switching disappears and the duration of domain switching is shortened.     

Temperature-induced fractionation of oxygen isotopes of diatom frustules and growth water in Lake Sihailongwan in Northeast China

Diatom oxygen isotopes have been widely applied in quantitative reconstruction of the paleoclimate and paleoenvironment, but have rarely been reported in China. In the present study, Lake Sihailongwan in Northeast China was selected for detailed investigation of oxygen isotopic fractionation between diatom frustules and lake water induced by growth temperature. This study involved a 2-year period of field monitoring of the lake water temperature at multiple depths and biweekly collections of traps for both sediment and water at shallow and bottom depths (7 and 49 m below the lake surface, respectively), diatom separation and purification of the trap sediments, and oxygen isotope measurement for diatom silica and lake water samples. The conditioned experiment conducted herein demonstrated that the laboratory device, methods and techniques used in this study were capable of generating reliable data for the typical oxygen isotope composition of diatom frustules. The data obtained revealed a prominent linear relationship between the oxygen isotope composition of the modern diatom and lake temperature during growth. The fractionation coefficient was about −0.185‰/°C−0.238‰/°C in the temperature range of 3.6–24°C, which is consistent with the observations from various aquatic environments and laboratory culture with different diatom taxa. These findings provide strong support for the dominant control of the growth temperature on the oxygen isotope fractionation between the diatom frustules and ambient water. A notable difference in the fractionation coefficient was observed between the surface and bottom diatom oxygen isotopes, suggesting that various depositional processes and taphonomic effects influenced the surface and bottom trap samples. Another factor leading to this difference may be that enrichment by evaporation and dilution by rainfall have a stronger influence on the surface. Overall, the results presented here demonstrate significant progress in evaluation of diatom oxygen isotopes in China and draw attention to the differences between surface and bottom diatom oxygen isotope compositions.     

An improved 3-D ray tracing method using linear traveltime interpolation

An approach of three-dimensional seismic ray tracing is presented, which is derived from adopting two-dimensional linear traveltime interpolation (LTI). By adjusting the forward process using the partition of grid interface, and backward step by considering more directions, the new approach is suitable for the application of three-dimensional models. The calculation results show that, with the same accuracy, the improved 3-D method is much faster than the method of traditional LTI directly applied in the three-dimensional case.     

A security patch for a three-party key exchange protocol

The CLC protocol (proposed by Tzung-Her Chen, Wei-Bin Lee and Hsing-Bai Chen, CLC, for short) is a new three-party password-authenticated key exchange (3PAKE) protocol. This CLC protocol provides a superior round efficiency (only three rounds), and its resources required for computation are relatively few. However, we find that the leakage of values A _V and B _V in the CLC protocol will make a man-in-the-middle attack feasible in practice, where A _V and B _V are the authentication information chosen by the server for the participants A and B. In this paper, we describe our attack on the CLC protocol and further present a modified 3PAKE protocol, which is essentially an improved CLC protocol. Our protocol can resist attacks available, including man-in-the-middle attack we mount on the initial CLC protocol. Meanwhile, we allow that the participants choose their own passwords by themselves, thus avoiding the danger that the server is controlled in the initialization phase. Also, the computational cost of our protocol is lower than that of the CLC protocol.     

HLA-B*6701 as a subtype performing post-selected marking gene for cervical cancer

A method of sequence-based typing (SBT) has been adopted to assort types of exons 2 and 3, which have the most polymorphism, of HLA-B locus of the Tujia nation group in Hubei province. The correlation among the HLA-B alleles, human papillomavirus (HPV) infection and cervical cancer risk has also been investigated. Under the condition of resident location and age, race unified, 100 specimens of cancer patients were sampled as a case group, of which 86 were HPV positive and were screened for HLA-B alleles; while 187 specimens were taken from healthy people, of which 92 were HPV negative as a control group. The result shows that by comparing the above mentioned 86 HPV positive cervical cancer group and 92 HPV negative normal group, it was concluded that HLA-B*6701 was only found in the cervical cancer group (p < 0.034), which shows that HLA-B*6701 can be used as an important candidate biological marking gene for generation of cervical cancer in Wufeng county of Hubei province.     

Solvothermal synthesis and ferromagnetic property of bamboo-shoot-like oriented carbon micromaterials

Bamboo-shoot-like oriented carbon micromaterials (BOCMs) were synthesized by a solvothermal method at 450°C for 4 h using deoiled asphalt (DOA) as carbon source, toluene as solvent, ferrocene as catalyst precursor and amphiphilic triblock copolymer P123 as surfactant. The morphology and structure of the products were characterized by X-ray diffraction, field emission scanning electron microscopy, high resolution transmission electron microscopy and Fourier transform infrared spectroscopy. The results reveal that the obtained products have good distribution with uniform diameters of about 0.5 μm and the lengths of 1–1.5μm, and hydrogen-carbon bonds are observed on the surface of BOCMs. The growth mechanism of BOCMs is discussed, in which that the catalysis of ferrocene and the dispersion and assembly of the aromatic molecules of DOA directed by P123 are critical to the formation of the BOCMs. The coercivity value (231.91 Oe) from the measurement of a vibrating sample magnetometer shows that the BOCMs have an obvious ferromagnetic behavior.