Eigenvalue analysis and estimation on dynamic quality of mechanical assembly

As an important manufacturing process, mechanical assembly affects directly product quality. Conventional quality inspections and estimations of mechanical assembly are primarily concentrated in “static quality”, such as size coordination, shaping and positioning tolerances, etc. However, mechanical assembly actually has its own dynamic quality, which contributes to that of whole product. Inspecting only static quality is thus incomplete for quality estimation of the assembly. On the basis of substructuring method, this paper at first applies eigenvalue analysis to investigate the effects of assembling process on the dynamic transfer-functions, expressed by spectral-based frequency response functions (FRFs), of substructural components involved in the process. Eigenvalue modules of FRF-matrix-ratios of FRF before assembling to that after assembling are analyzed to quantify the effects, which are consequently indicated by the mean module. Then, according to the explicit definition of “dynamic quality of mechanical assembly” introduced in this paper, dynamic quality matrix of mechanical assembly and its mean eigenvalue module are worked out and chosen to be the right quantitative measure and indicator for dynamic quality estimation of assembly system. Meanwhile, a lumped-parameter model and its experimental counterpart are employed to validate effectiveness of the analytical outcomes obtained and the quality estimation method established in the study

Investigation on dynamic characteristics of mechanical assembly

Mechanical assembly is important process affecting product dynamic quality. To completely inspect assembly quality, dynamic characteristic analysis is necessary. Based on substructuring dynamic analysis, this paper theoretically analyzes the changes of dynamic characteristics due to assembling process. Assembly coupling dynamic stiffness computed by inverse substructuring analysis is considered as a critical measure on the changes. The results obtained have been well validated by a lumped-parameter model for two-level of substructures

Effects of Bushenyiqihexue Formula on the Endometrial Gland Apoptosis in Mice with Blastocyst Implantation Dysfunction

ObjectiveTo observe the effects of Bushenyiqihexue Formula (Formula for Tonifying the Kidney, Replenishing qi and Harmonizing Blood, FTKRQHB) on the endometrial gland apoptosis in the mice with blastocyst implantation dysfunction.MethodsThe mice with the first-day pregnancy were divided into the control, model and treatment groups, with 30 in each group, and blastocyst implantation dysfunction was induced by subcutaneous injection of mifepristone in the mice of the model and treatment groups. The pregnancy rate and implantation number of blastocysts were measured and the expressions of proliferating cell nuclear antigen (PCNA), Bax, Bcl-2, and activated caspase-3 were detected in all the three groups.ResultsThe model group had significantly depressed pregnancy rate, implantation number of blastocysts and apoptosis index, and elevated proliferation index of endometrial gland as compared with the control group (P<0.05 or P<0.01). Administration of FTKRQHB (the treatment group) resulted in significant increases in pregnancy rate, implantation number of blastocysts and apoptosis index of the endometrial gland, and a significant decrease in the proliferation index of the endometrial gland as compared with the model group (P<0.05 or P<0.01). The differences in the four indexes between the treatment group and control group were not significant statistically. The Bax and activated caspase-3 expressions in endometrial gland in the model group became significantly lower than that of the control group (P<0.01), whereas those in the treatment group were significant higher than that of the model group (P<0.01). However, the Bax and activated caspase-3 expressions in endometrial gland were similar in both treatment and control groups.ConclusionPromoting the increases in Bax and activated caspase-3 expressions in the endometrial gland and bringing into balance between apoptosis and proliferation of the glandular cells at the implantation window phase by FTKRQHB may contribute to the effects of promoting the establishment of endometrial receptivity and improving blastocyst implantation dysfunction

Deep Variational Luenberger-type Observer for Stochastic Video Prediction

Considering the inherent stochasticity and uncertainty, predicting future video frames is exceptionally challenging. In this work, we study the problem of video prediction by combining interpretability of stochastic state space models and representation learning of deep neural networks. Our model builds upon an variational encoder which transforms the input video into a latent feature space and a Luenberger-type observer which captures the dynamic evolution of the latent features. This enables the decomposition of videos into static features and dynamics in an unsupervised manner. By deriving the stability theory of the nonlinear Luenberger-type observer, the hidden states in the feature space become insensitive with respect to the initial values, which improves the robustness of the overall model. Furthermore, the variational lower bound on the data log-likelihood can be derived to obtain the tractable posterior prediction distribution based on the variational principle. Finally, the experiments such as the Bouncing Balls dataset and the Pendulum dataset are provided to demonstrate the proposed model outperforms concurrent works

Progress of photonuclear cross sections for medical radioisotope production at the SLEGS energy domain

Photonuclear reactions using a laser Compton scattering (LCS) gamma source provide a new method for producing radioisotopes for medical applications. Compared with the conventional method, this method has the advantages of a high specific activity and less heat. Initiated by the Shanghai Laser Electron Gamma Source (SLEGS), we conducted a survey of potential photonuclear reactions, (\upgamma,n), (\upgamma,p), and (\upgamma,\upgamma') whose cross-sections can be measured at SLEGS by summarizing the experimental progress. In general, the data are rare and occasionally inconsistent. Therefore, theoretical calculations are often used to evaluate the production of medical radioisotopes. Subsequently, we verified the model uncertainties of the widely used reaction code TALYS-1.96, using the experimental data of the \ce{^100Mo}(\upgamma,n)\ce{^99Mo}, \ce{^65Cu}(\upgamma,n)\ce{^64Cu}, and \ce{^68Zn}(\upgamma,p)\ce{^67Cu} reactions.Comment: 16 pages, 19 figure