Simulation on Reliability Enhancement Testing Technology of Ramming System

Ramming system is the key device to guarantee the firing speed of self-propelled gun. Based on traditional reliability enhancement testing method, a new kind of reliability enhancement testing simulation method of ramming system is put forward firstly. In CAD software Pro/E and dynamic simulation software ADAMS, the virtual prototype of ramming system is established. In EASY5 software, the corresponding hydraulic system and control system models are built. The reliability enhancement testing virtual environment of ramming system is developed using the mechanical-electrical-hydraulic co-simulation technology. Based on the load spectra provided by virtual prototype, and the stress distribution provided by finite element analysis and material's S-N curve(S is fatigue strength, N is fatigue life), a model of fatigue enhancement coefficient is established through the failure mechanism analysis. The simulation processes and simulation results show the feasibility of reliability enhancement testing based on virtual prototype, and provide sufficient theory reference for structure improvement and optimization of ramming system.

Diagnostic accuracy of enhanced liver fibrosis test to assess liver fibrosis in patients with chronic hepatitis C

BACKGROUND:The prognosis and clinical management of patients with chronic liver diseases are closely related to the severity of liver fibrosis.Liver biopsy is considered the gold standard for the staging of liver fibrosis.However,it is an invasive test sometimes related to complications.This study aimed to assess the diagnostic value of enhanced liver fibrosis(ELF) test to predict liver fibrosis in patients with chronic hepatitis C.METHODS:This study included 162 patients with liver disease and 67 healthy controls.Hyaluronic acid,tissue inhibitor of matrix metalloproteinase type 1,and amino-terminal propeptide type III procollagen were measured by enzymelinked immunosorbent assay with the ELF test ADVIA Centaur(Siemens Healthcare Diagnostics Inc.).Fibrosis stage was determined using the Metavir scoring system.RESULTS:In our study,for the diagnosis of significant fibrosis(Metavir F≥2) a cut-off value 】7.72 provides a sensitivity of 93.0% and a specificity of 83.0%.The areas under the receiver operator characteristic curve,sensitivity,specificity,and positive and negative predictive values were 0.94,93.3%,81.0%,93.3%,and 81.0%,respectively(P【0.001).For the diagnosis of cirrhosis(Metavir F=4) a cut-off value 】9.3 provides a sensitivity of 93.0% and a specificity of 86.0%.The areas under the receiver operator characteristic curve,sensitivity,specificity,and positive and negative predictive values were 0.94,79.1%,90.8%,75.6%,and 92.3%,respectively(P【0.001).CONCLUSIONS:The ELF test is a promising non-invasive method for assessing liver fibrosis in patients with chronic hepatitis C.It is effective in the diagnosis of both fibrosis and cirrhosis.

Endocrine Disruption of Cadmium in Rats Using the OECD Enhanced TG 407 Test System

Objective To evaluate the endocrine disrupting effects of cadmium （Cd） using OECD enhanced TG407 test guideline. Methods Sprague-Dawley （SD） rats were randomly divided into six groups and accordingly administered with 0, 1, 2.5, 5, 10, 20 mg/kg.BW/day of Cd by gavage for 28 days. Body weight, food consumption, hematology, biochemistry, sex hormone levels, urinary β2-microglobulin, organ weights and histopathology and estrous cycle were detected. Results Cd could significantly decrease animals＇ body weight （P〈0.05）. Serum luteinizing hormone （LH） at 10-20 mg/kg.BW groups and testosterone （T） at 2.5 and 10 mg/kg.BW groups decreased significantly （P〈0.05）. However, no statistically significant change was found in urinary β2-microglobulin among Cd-treatment groups （P〉0.05）. Endpoints related to female reproduction including uterus weight and histopathological change at 10-20 mg/kg.BW groups showed significant increase （P〈0.05）. While among male rats in 2.5, 10, 20 mg/kg.BW groups, weight of prostate, thyroids, and seminal vesicle glands significantly decreased （P〈0.05）. Moreover, no histopathological change was observed in kidney. Conclusion Results suggested that Cd can cause endocrine disrupting effects in SD rats. Comparing with possible renal toxicity of Cd, its toxicity on endocrine system was more sensitive.

Consistency analysis of accelerated degradation mechanism based on gray theory

A fundamental premise of an accelerated testing is that the failure mechanism under elevated and normal stress levels should remain the same. Thus, verification of the consistency of failure mechanisms is essential during an accelerated testing. A new consistency analysis method based on the gray theory is pro- posed for complex products. First of all, existing consistency ana- lysis methods are reviewed with a focus on the comparison of the differences among them. Then, the proposed consistency ana- lysis method is introduced. Two effective gray prediction models, gray dynamic model and new information and equal dimensional （NIED） model, are adapted in the proposed method. The process to determine the dimension of NIED model is also discussed, and a decision rule is expanded. Based on that, the procedure of ap- plying the new consistent analysis method is developed. Finally, a case study of the consistency analysis of a reliability enhancement testing is conducted to demonstrate and validate the proposed method.

Durbin test with enhanced detection performance to mismatched signal

This paper deals with the problem of detecting a signal whose amplitude is a scaling factor in the presence of homogeneous Gaussian noise with unknown covariance matrix.Since no uniformly most powerful test exists for the problem at hand,we devise and assess a detection strategy based on the well-known Durbin test design criteria.The closed-form expressions for the probabilities of false alarm and detection of the Durbin test are derived,which show that it bears a constant false alarm rate property against the noise covariance matrix.At the analysis stage,the performance of the new receiver is assessed,also in comparison with some classical adaptive detectors,both in matched and in mismatched signal cases.The results show that the proposed detector achieves a visible performance improvement in the presence of severe steering vector mismatch,while maintaining an acceptable detection loss for matched signal.