Numerical Simulations of Jet Flow Inside Launching Box and Design of Pressure Opening the Covers of Missile Launching Box

Numerical simulations are presented for jet flow inside a launching box. The predictions are based on solutions of the unsteady three-dimensional Reynolds-averaged Navier-stokes equations. Since the pressure opening the forward cover is given, the pressure opening the backward cover is designed by analyzing the flow field inside the launching box. The κ -ε turbulent model is presented and the structured meshes are used through the whole computational field.

Does high intraocular pressure exclude an open globe injury?

Dear Sir,Ocular trauma is a topic of unresolved controversies and there are continuous controversial and debatable diagnostic and management strategies for open-globe injuries[1].Amongst many types of ocular trauma,the open globe injury is the most serious due to its very poor visual prognosis and young population of patients are mostly affected[2].The treatment outcome may be improved by prompt diagnosis,and immediate surgical repair performed to high standard[3].Amongst the other clinical signs the intraocular pressure(IOP)is found to be particularly reduced and conventionally this is considered as a very reliable indicator of occult globe

Effect of body position on the pathogenesis of asymmetric primary open angle glaucoma

AIM： To explore the pathogenesis of asymmetric primary open angle glaucoma（POAG） in both eyes by comparing the intraocular pressure（IOP） of patients who sleep in different positions and to investigate the relationship between IOP variations and sleep positions.METHODS： One hundred and thirty-one patients with asymmetric POAG and forty-six healthy volunteers were enrolled. All participants completed a questionnaire that provided information about their sleep laterality. The cup disc ratio（C/D） and visual field defect established binocular asymmetry. The IOP of both eyes was measured using i Care parameters after the patients were asked to change body position. The ＂worse＂ and ＂better＂ eyes were identified according to the diagnosis, whereas the ＂dependent＂ and ＂independent＂ eyes were defined according to the lateral position. RESULTS： No significant difference in sleep laterality was observed between healthy people and patients with POAG（F=3.195, P=0.362）. Among the enrolled patients, the IOP of the dependent eye was always greater than that of the independent eye in the lateral position（P〈0.05）. In the patients with binocular asymmetric POAG, the questionnaire clearly showed that 85.7% of left side preferences were found their left eyes to be the worse eyes and the right eyes of 71.4% patients with a right side preference were the more serious. When the asymmetric C/D ratio was greater than or equal to 0.2, the worse eye of patients with POAG and a preferred sleeping position was the dependent eye（χ~2=16.762, P=0.001）.CONCLUSION： A higher IOP was measured in the dependent eye in the lateral position. The long-term tendency to choose a lateral sleeping position might lead the dependent eye to manifest more severe symptoms than the independent eye. Thus, the lateral sleeping position might be one cause of asymmetric POAG.

Factors affecting cerebrospinal fluid opening pressure in patients with spontaneous intracranial hypotension

Objective： Spontaneous intracranial hypotension （SIH） is recognized far more commonly than ever before. Though usually characterized by low cerebrospinal fluid （CSF） pressure, some patients with SIH are observed to have normal pressure values. In this study, we aimed to confirm the proportion of patients with normal CSF opening pressure （CSF OP） and explore the factors affecting CSF OP in SIH patients. Methods： We retrospectively reviewed 206 consecutive SIH patients and analyzed their clinical and imaging variables （including demographic data, body mass index （BMI）, duration of symptoms, and brain imaging findings）. Univariate and multiVariate analyses were performed to identify the potential factors affecting CSF OP. Results： In a total of 114 （55.3%） cases the CSF OP was 〈60 mmH2O （1 mmH2O=9.80665 Pa）, in 90 （43.7%） cases it was between 60 and 200 mmH2O, and in 2 （1.0%） cases it was 〉200 mmH2O. Univadate analysis showed that the duration of symptoms （P〈0.001）, BMI （P〈0.001）, and age （P=0.024） were positively correlated with CSF OP. However, multivariate analysis suggested that only the duration of symptoms （P〈0.001） and BMI （P〈0.001） were strongly correlated with CSF OP. A relatively high R2 of 0.681 was obtained for the multivariate model. Conclusions： Our study indicated that in patients without a low CSF OP, a diagnosis of SIH should not be excluded. BMI and the duration of symptoms can influence CSF OP in SIH patients, and other potential factors need further investigation.

MECHANISM OF WALL PRESSURE FLUCTUATIONS BENEATH THE OPEN CHANNEL FLOW

Based on the measured results that wall pressure fluctuations are mainly de- cided by coherent structures of turbulence, the relationship between root-mean- square wall pressure and wall shear stress in turbulent shear flow and that between the intensities of pressure and fluctuating velocity in homogeneous and isotropic turbulence are established in this paper. These relationships are consistent with former works, and have good agreement with experimental data. The paper also dis- cusses the concept of 'apparent pressure' on the wall in mean flow.