Profile-based Maximum Penalised Likelihood Trajectory Estimation from Space-borne LOS Measurements

Estimating the boost-phase trajectory of a ballistic missile using line of sight measurements from space-borne passive sensors is an important issue in missile defense. A well-known difficulty of this issue is the poor-observability of the target motion. A profile-based maximum penalised likelihood estimator is presented, which is expected to work in poor-observability scenarios. Firstly, a more adaptable boost-phase profile is proposed by introducing unknown parameters. Then, the estimator is given based on the Bayesian paradigm. After that, a special penalty for box constraint is constructed based on a mixed distribution. Numerical results for some typical scenarios and sensitivity with respect to a priori information are reported to show that the proposed estimator is promising

The Physiological Mechanism of Improved Formaldehyde Resistance in Petunia hybrida Harboring a Mammalian cyp2e1 Gene

AbstractCytochrome P450 CYP2E1 is mainly present in hepatocytes in the livers of mammals, where it plays an important role in the metabolism of xenobiotic organic substances. Previous studies showed that transgenic petunia (Petunia hybrid) plants harboring a mammalian cyp2e1 gene (designated cyp2e1-transgenic petunia) exhibited increased resistance to formaldehyde stress. In this study, we used cyp2e1-transgenic petunia plants to analyze physiological indexes related to formaldehyde stress responses. The results indicated that under formaldehyde stress, the malondialdehyde content in cyp2e1-transgenic petunia plants was lower than in β-glucuronidase gene (gus)-transgenic and wild-type petunia plants. The activities of both superoxide dismutase and peroxidase in the cyp2e1-transgenic plants were higher than in gus-transgenic and wild-type plants. The alcohol dehydrogenase activity was slightly increased and more glutathione was consumed. Additionally, under formaldehyde stress, the levels of plant hormones including indole-3-acetic acid, zeatin and abscisic acid in cyp2e1-transgenic petunia plants displayed decreasing trends, whereas the level of gibberellic acid displayed an increasing trend. In contrast, the indole-3-acetic acid, zeatin and abscisic acid levels in gus-transgenic and wild-type petunia plants displayed increasing trends, whereas the gibberellic acid level displayed a decreasing trend. At 72h after incubation of 0.5g of cyp2e1-transgenic petunia plants in 40mL of treatment solution containing formaldehyde at 50mg · L−1, the formaldehyde content remaining in the treatment solution was close to zero while approximately half of original formaldehyde remained in the treatment solutions containing gus-transgenic and wild-type petunia plants

Selection of an Analysis Wavelength: An Interesting Example Involving Solvatochromism and the Zwitterionic Dimroth-Reichardt's Betaine ET-30 Dye

Article on the selection of an analysis wavelength and an interesting example involving solvatochromism and the zwitterionic Dimroth-Reichardt's ET-30 betaine dye

Loading and Contact Stress Analysis on the Thread Teeth in Tubing and Casing Premium Threaded Connection

Loading and contact stress distribution on the thread teeth in tubing and casing premium threaded connections are of great importance for design optimization, pretightening force control, and thread failure prevention. This paper proposes an analytical method based on the elastic mechanics. This is quite different from other papers, which mainly rely on finite element analysis. The differential equation of load distribution on the thread teeth was established according to equal pitch of the engaged thread after deformation and solved by finite difference method. Furthermore, the relation between load acting on each engaged thread and mean contact stress on its load flank is set up based on the geometric description of thread surface. By comparison, this new analytical method with the finite element analysis for a modified API 177.8 mm premium threaded connection is approved. Comparison of the contact stress on the last engaged thread between analytical model and FEM shows that the accuracy of analytical model will decline with the increase of pretightening force after the material enters into plastic deformation. However, the analytical method can meet the needs of engineering to some extent because its relative error is about 6.2%~18.1% for the in-service level of pretightening force