Papers by Keyword: PGA

Abstract: Characteristics of cumulative absolute velocity parameter (CAV) of Lushan earthquake is discussed and presented in this paper. Based on a brief analysis of the background information of the Lushan earthquake, the value of CAV which is calculated from the recorded data of the Lushan earthquake is compared with the commonly used value peak ground acceleration (PGA). Accordingly, the relationship between the CAV and the PGA is studied, and 3 CAV/PGA ratio charts in 3 different sub-directions are obtained. Then the linear fitting operation and the polynomial fitting operation are performed to analyze the potential discipline and characteristics thereof. The applicability of utilizing the CAV parameter in earthquake observation systems is further studied in this paper, and the CAV parameter is cooperated with the currently used value PGA to provide the work of earthquake observation and emergency response with corresponding theoretical basis.

Abstract: In this paper, the influence of topography on ground-motion intensity parameter, response spectrum, peak ground acceleration (PGA) and the ratio of response spectrum were studied based on the measured data from large scale shaking table test and observation stations in XiShan park for Wenchuan earthquake. The results show that: in the EW direction, the height do not affect PGD, SMA, VSI and HI, while V_RMS decreases slightly at the middle of the slope, the other intensity parameters increase with the increase of height. In the EW direction, the height has no influence on PGD, V_RMS, SMA, SED, A_RMS, VSI and HI, while other parameters increase as the height increase. In the UD direction, the height has no influence on SMV, PGD, V_RMS, SMV, ASI, VSI and HI, while A_RMS decreases at the middle of the slope, and the other intensity parameters increase as the height increase. Ignoring the local topographic effect, the amplitude of response spectrum increases with the increase of height at the part of short period (T1s), the part of long period (T>1s) is not effected by height. The ground motion will be amplified by local canyon topography, and the influence of local topography is larger than height. The research carried out in paper will deepen the understanding of topographic effect. 0 Preface Earthquake often cause extensive rock slope failures and various types of mass movement in mountainous areas. Catastrophic seismically-induced landsides are among the Earths most powerful geomorphic events, causing sudden and dramatic changes to the landscape, creating high risks to both infrastructures and life, and reputedly causing large economic losses. Seismic waves interacting with topography lead to amplification and deamplification of resulting ground motion. In the western mountainous areas of China, the topography is extremely complex, many large hydropower stations were built in narrow valleys and many large bridge piers were built on valleys and hillsides, so the research about topographic effect is essential to the seismic design of large-scale projects. Topographic effect is always analyzed with following three approaches: motion observation, analytical analysis and numerical analysis. The motion observation is regarded as the most efficient and common approach [1]. Long time ago, the researchers found that the intensity of buildings built on local convex topography was abnormal, in order to reveal the reason of abnormal intensity, array stations were constructed specially to study the effect of local convex topography on ground motion, some observation data were obtained. Some L-7 type strong motion seismographs were installed at the crest and foot of Kagel and Josephine mountain, California, by Lawrence L. Davis and Lewis R. West, the 2 array stations had recorded several aftershocks record of SanFernando earthquake, which occurred on February 9, 1971[. Some L-7 type strong motion seismographs were also installed at the crest, hillside and foot of Butler mountain, Nevada, to record blasting vibration in test site. In 1984, in order to observe the topographic effect of rocky mountain, 8 observation stations were installed by B. E. Tucker, five stations were placed in two tunnels with different elevation, the other three were placed at the surface of outcropped rock [. After the 1989 Loma prieta earthquake, dense array stations of seven digital and triaxial seismographs were mounted on Robinwood Ridge, which is located at 7.3km northwest of epicenter, to analyze the reason of seriously damage on high-strength buildings and cracks of ground [4,. In China, a earthquake observation station was constructed in XiShan Park, ZiGong, SiChuan province in 2007, which recorded the main acceleration time history of WenChuan earthquake perfectly, the establishment of this station offers valuable data to researchers for exploring the local topographic effect on ground motion [6]. In 2010, a research was conducted by Wang Haiyun and Xie Lili with traditional spectral ratio method, some significant conclusions were drawn about the influence of topographic effect on ground motion [7]. In this paper, WenChuan seismic wave was analyzed in time and frequency domain to explore the influence of topography on ground-motion intensity parameters, response spectrum and spectrum characteristic.

Abstract: Anti-surfaceship missile firepower allocation is a complex and important problem to submarine command. The method of partheno-genetic algorithm (PGA) is suit for firepower allocating. While keeping the virtues of traditional genetic algorithm, PGA overcomes its defects. Because of employing more simply operators, PGA decreases the complexity of calculation. Basing on the mathematics model of missile firepower allocation and building the steps of PGA, a case of firepower allocation to submarine by PGA was applied. Simulation results indicated that PGA is a simple, effective and fast algorithm. PGA can solve the submarines missile firepower allocation problem effectively and can be satisfied with the requirement of real-time and fast to submarine command.

Abstract: The process conditions of immobilizing penicillin G acylase(PGA) by epoxy resin were studied. This experiment used the Box-Behnken experimental design and response surface methodology(RSM) to optimize the conditions of immobilizing PGA by epoxy resin. The results showed the best process conditions were pH 8.1, temperature 29°C, carrier of epoxy resin 1g and reaction time 24 h. On these conditions, the activity of the immobilized enzyme was 365.76 U g^-1, activity recovery rate was 62.82%. The characteristics of the immobilized PGA under optimal conditions had been measured and found that the optimum pH of immobilized enzyme was 9.0, the optimum temperature was 60°C. It has better continuous operation stability.

Abstract: 7-ATCA is a major intermediate of Cefditoren pivoxil. Literatures reported 7-ATCA was generally synthesized by the method of sheer chemistry or combinative method of biochemistry and chemistry. Considering reduction of environmental pollution, the combinative method has more preference. We optimized the amount of sodium iodide and 4-methyl-5-thiazolaldehyde in Wittig reaction and the sorts of reagents for removing C-4 deprotection group. 7-ATCA was obtained after penicillin acylase hydrolysis of C-7 protection group in a mild condition. The structure of 7-ATCA was characterized by ¹H NMR and the total yield was up to 55%.

Abstract: The issue of power reliability in a middle-voltage distributed network is now emerging as an international concern. Therefore, in this paper, an optimal model with two objectives, reliability and economy, for network planning of a distributed system is established. Based on the Pareto optimum theory, the Non-dominated Sorting Genetic algorithm II (NSGA-II), which is combined with the specific genetic operators in Partheno-genetic algorithm (PGA), is used to solve the proposed model. By the obtained well-proportioned Pareto solution set, the final network planning scheme can be found according to different real engineering conditions, thus different demands in engineering can be satisfied. A typical example is used to verify the proposed model and algorithm effective.

Abstract: A tubal knitted scaffold fabricated from poly(lactic acid) (PLA) yarns was given in this work. The performance of the scaffold during degradation in vitro and the morphology of the scaffold with cells (monkey dermal fibroblasts) were examined. The scaffold fabricated from poly(glycolic acid) (PGA) yarns was manufactured as the control. Results showed that the PLA scaffold could keep much more tensile strength during degradation in vitro, compared with the PGA scaffold. However, cell attachment and proliferation on the PGA scaffold were better than on the PLA scaffold.

Abstract: Poly(glycolic acid) (PGA) fibers produced by melt-spinning technology with different parameters may possess different structures, which may lead to different degradation behavior. In this paper, PGA fibers produced by different technology parameters were placed in phosphate buffer solution (PBS) (pH=7.4) at 37 °C up to 2 weeks to investigate the effect of melt-spinning technology on the degradation in vitro. Changes in weight loss and tensile strength of PGA fibers during degradation were investigated. The results showed that drawing multiple, drawing temperature and inherent viscosity of polymer had the influence on the performance of PGA fiber during degradation. The changes in weight loss and tensile strength during degradation in vitro indicated that the PGA fiber produced with higher drawing multiple degraded more slowly. The PGA fiber produced on higher drawing temperature degraded faster. The PGA fiber made from higher inherent viscosity polymer degraded more slowly.

Abstract: Biodegradable nanofiber has become a popular candidate as tissue engineering scaffolds due to its biomimic structure as natural extracellular matrix (ECM). Certain tissue regeneration may require prolonged in vitro culture time for cellular reorganization and tissue remodeling. Therefore, long term understanding of cellular effects on scaffold degradation is needed. Although there are some degradation studies on nanofiber, degradation study of nanofibers with cell culture is rare. In our study, polyglycolide (PGA), poly(DL-lactide-co-glycolide) (PLGA), poly(L-lactide-co-ε- caprolactone) [P(LLA-CL)] were electrospun into nanofiber scaffolds. The scaffolds were cultured with porcine smooth muscle cells (PSMC) for up to 3 months to evaluate their degradation behavior and cellular response. The results showed that their degradation rates were in the order of PGA>>PLGA>P(LLA-CL). PGA nanofiber degraded in 3 weeks and only supported cell growth in the first few days. Cell culture accelerated the surface erosion of PLGA and P(LLA-CL) nanofiber while the bulk degradation remained unaffected. Furthermore, the cell culture did not significantly reduce the mechanical strength of PLGA and P(LLA-CL) during degradation.

Abstract: Tendon is an important supportive tissue of human body responsible for normal physical activity. However, tendon damage and defect remain an important factor for causing disability. The rise of tissue engineering technology provides an effective means of tendon reconstruction and repair, which will bring promise for functional recovery. In our center, tendon engineering is one of major research areas. We have performed the in vivo study by using tenocytes and polyglycolic acid fibers to reconstruct and repair tendon defect in hen and porcine models. The results demonstrated the successful regeneration and repair of tendon defects created in different models. In addition, tendon function was also well recovered by generated autologous tendon tissue that possesses strong biomechanical property. Recently, we have also successfully generated tendon tissue in vitro by using static strain device and bioreactors, which could be potentially transplanted as the tendon graft for tendon defect repair.