Search

A numerical study of the longitudinal pulsed detonation (LPD) is conducted in the present paper. The occurrence mechanism of the LPD, called shock wave amplification by coherent energy release, is verified preliminarily in this study. To be specific, upstream propagating shock waves, which originate from the outlet, induce a specific gradient of reactant distribution, and then detonation waves are ignited and evolve along the gradient in close succession. It is worth noting that the occurrence of LPD does not mean that the LPD will necessarily be sustained. The low injection pressure ratio PR (i.e., the ratio of inlet pressure to outlet pressure) = 1.3 is found to be conducive to the sustenance of the LPD instability in the baseline model. A lower PR (PR ≤ 1.2) or a slightly higher PR (1.4 ≤ PR ≤ 1.8) shall lead to an unstable detonation or quenching of detonations, while a much higher PR (PR > 1.8) contributes to the formation of stable canonical rotating detonation waves. In addition, the combustion regimes of five combustors of different heights at different PR are explored. As the combustion chamber height increases, the PR of the sustainable LPD is nearly linearly increasing, and its operating frequency decreases gradually. The calculation formula between the sustainable LPD propagating frequency and the natural acoustic resonance frequency of the combustor is employed and discussed, but in consideration of its imperfection, further investigation is required. [ABSTRACT FROM AUTHOR]

Gnutella, a popular file-sharing application, relies on flooding queries to all peers. Although flooding is simple and robust, it is not scalable. This paper uses an ontology model to represent user's interests. An interest-based group model is used to organize the peers with similar interests into a subnet. The content location solution is on top of the existing Gnutella network. By using the algorithm, called interest-based subnet, a significant amount of flooding can be avoided, making Gnutella a more competitive solution. The extensive simulation results show the effectiveness of the proposed model in peer-to-peer system. [ABSTRACT FROM AUTHOR]

Objective: To investigate the effects of butylphthalide (NBP) on learning and memory related ability, hydrogen sulfide (H 2 S) content in hippocampus and amygdala, cystathionine-β-synthase (CBS) expression and mitochondrial ATPase activity in rats with chronic alcoholism. Methods: Ninety SD male rats were randomly divided into three groups: normal control group (NC), model group (M) and butylphthalide remedy group (BR). Except for the control group, the water solution containing 6% (v/v) alcohol was used as the sole source of drinking water in the other two groups. After 14 days of feeding, the butylphthalide remedy group was injected with NBP intraperitoneally at the dose of 5 mg/kg once a day for 14 consecutive days, and the remaining two groups were injected with the same dose of normal saline. The control group subsequently used the Morris water maze method to observe and record the animals after entering the water. The time required for the underwater platform, their strategies and their swimming trajectories could analyze and infer the animal's ability to learn and remember. H 2 S concentration, CBS expression and mitochondrial ATPase activity in hippocampus and amygdale were dectected. Results: Compared with NC group, the latency period and swimming distance of M group were increased, the content of H 2 S and the mean optical density of CBS in hippocampus and amygdala were increased, and the activity of mitochondrial ATPase in hippocampus and amygdala was decreased significantly ( P ＜0. 01) . Compared with the M group, the latency period and swimming distance of learning and memory performance of BR group were decreased, the content of H 2 S and the mean optical density of CBS in hippocampus and amygdala were decreased, and the activity of mitochondrial ATPase in hippocampus and amygdala was increased significantly ( P ＜0. 01) . Conclusion: NBP can alleviate the effect of ethanol on learning and memory in rats, which may be related to the effect of NBP on the concentration of H 2 S and the expression of CBS in the amygdala of hippocampus and the increase of ATPase activity.

Objective: To investigate the feasibility and therapeutic effect of subcutaneous pedicle screw-rod system with modified placement in treatment of Tile B pelvic fractures., Methods: From June 2014 to August 2015, 14 patients with Tile B pelvic fractures were treated by subcutaneous pedicle screw-rod system with modified placement in the anterior inferior iliac spine and pubic tubercle. There were 8 males and 6 females, aged from 23 to 65 years with an average of 42 years. Operative time, intraoperative blood loss, fracture healing and postoperative complication were observed and clinical effects were evaluated by Matta reduction standard and Majeed score., Results: All patients were followed up from 8 to 15 months with an average of 10.5 months. Operative time was 25 to 45 min with an average of 32 min;intraoperative blood loss was 10 to 35 ml with an average of 18 ml. All fractures got primary healing and healed time was 9 to 14 weeks with an average of 12.5 weeks. No postoperative incision infection, internal fixation failure and ectopic ossification were found, 4 cases occurred unilateral lateral femoral cutaneous nerve injury and 1 case occurred unilateral femoral nerve paralysis, but all restored finally. According to Matta criteria, reduction was excellent in 7 cases, good in 5 cases, fair in 2 case. According to Majeed score system, the functional evaluation at last follow-up was excellent in 5 cases, good in 7 cases, fair in 2 cases with the average score of 81.50±8.05., Conclusions: Subcutaneous pedicle screw-rod system with modified placement in the anterior inferior iliac spine and pubic tubercle have advantages of strong reduction, less trauma and complications, and is a promising surgical method in the treatment of Tile B pelvic fractures., Competing Interests: The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose.