大型复杂结构的两阶段损伤诊断方法

综述了用于结构损伤识别的各种方法,提出了进行大型复杂结构损伤诊断所面临的问题,列出了已有的两步法的思路、方法,指出了需要研究的方向,为进行大型复杂结构的损伤诊断提供了参考。

Structural damage detection method based on information fusion technique

Multi-source information fusion （MSIF） is imported into structural damage diagnosis methods to improve the validity of damage detection. After the introduction of the basic theory, the function model, classifications and mathematical methods of MSIF, a structural damage detection method based on MSIF is presented, which is to fuse two or more damage character vectors from different structural damage diagnosis methods on the character-level. In an experiment of concrete plates, modal information is measured and analyzed. The structural damage detection method based on MSIF is taken to localize cracks of concrete plates and it is proved to be effective. Results of damage detection by the method based on MSIF are compared with those from the modal strain energy method and the flexibility method. Damage, which can hardly be detected by using the single damage identification method, can be diagnosed by the damage detection method based on the character-level MSIF technique. Meanwhile multi-location damage can be identified by the method based on MSIF. This method is sensitive to structural damage and different mathematical methods for MSIF have different preconditions and applicabilities for diversified structures. How to choose mathematical methods for MSIF should be discussed in detail in health monitoring systems of actual structures.

Biochemical metabolic changes assessed by ^(31)P magnetic resonance spectroscopy after radiation-induced hepatic injury in rabbits

AIM： To compare the features of biochemical metabolic changes detected by hepatic phosphorus-31 magnetic resonance spectroscopy （^31p MRS） with the liver damage score （LDS） and pathologic changes in rabbits and to investigate the diagnostic value of ^31p MRS in acute hepatic radiation injury. METHODS： A total of 30 rabbits received different radiation doses （ranging 5-20 Gy） to establish acute hepatic injury models. Blood biochemical tests, ^31p MRS and pathological examinations were carried out 24 h after irradiation. The degree of injury was evaluated according to LD5 and pathology. Ten healthy rabbits served as controls. The MR examination was performed on a 1.5 T imager using a 1H/^31P surface coil by the 2D chemical shift imaging technique. The relative quantities of phosphomonoesters （PME）, phosphodiesters （PDE）, inorganic phosphate （Pi） and adenosine triphosphate （ATP） were measured. The data were statistically analyzed. RESULTS： （1） Relative quantification of phosphorus metabolites： （a） ATP： there were significant differences （P 〈 0.05） （LDS-groups：control group vs mild group vs moderate group vs severe group, 1.83±0.33 vs 1.55±0.24 vs 1.27±0.09 vs 0.98±0.18; pathological groups： control group vs mild group vs moderate group vs severe group, 1.83±0.33 vs 1.58±0.25 vs 1.32±0.07 vs 1.02±0.18） of ATP relative quantification among control group, mild injured group, moderate injured group, and severe injured group according to both LDS grading and pathological grading, respectively, and it decreased progressively with the increased degree of injury （r = -0.723, P = 0.000）. （b） PME and Pi; the relative quantification of PME and Pi decreased significantly in the severe injured group, and the difference between the control group and severe injured group was significant （P 〈 0.05） （PME： 1DS- control group vs LDS-severe group, 0.86±0.23 vs 0.58±0.22, P = 0.031; pathological control group vs pathological severe group, 0.86±0.23 vs 0.60±0.21, P = 0.037; Pi： LDS-control group vs LDS-severe group, 0.74±0.18 vs 0.43±0.14, P = 0.013; pathological control group vs pathological severe group, 0.74±0.18 vs 0.43±0.14, P = 0.005） according to LDS grading and pathological grading, respectively. （c） PDE; there were no significant differences among groups according to LDS grading, and no significant differences between the control group and experimental groups according to pathological grading. （2） The ratio of relative quantification of phosphorus metabolites： significant differences （P 〈 0.05） （LDS- moderate group and LDS-severe group vs LDS-control group and LDS-mild group, 1.94±0.50 and 1.96±0.72 vs 1.43±0.31 and 1.40±0.38） were only found in PDE/ATP between the moderate injured group, the severe injured group and the control group, the mild injured group. No significant difference was found in other ratios of relative quantification of phosphorus metabolites.CONCLUSION： ^31p MRS is a useful method to evaluate early acute hepatic radiation injury. The relative quantification of hepatic ATP levels, which can reflect the pathological severity of acute hepatic radiation injury, is correlated with LDS.

Practical guidelines for diagnosis and early management of drug-induced liver injury

The spectrum of drug-induced liver injury （DILI） is both diverse and complex. The first step in diagnosis is a suspicion of DILl based on careful consideration of recent comprehensive reports on the disease. There are some situations in which the suspicion of DILI is particularly strong. Exclusion of other possible etiologies according to the pattern of liver injury is essential for the diagnosis. In patients with suspected DILl, diagnostic scales, such as the Councils for International Organizations of Medical Sciences/ Roussel Uclaf Causality Assessment Method （CIOMS/RUCAM） scale, may be helpful for the final diagnosis. Early management of DILl involves prompt withdrawal of the drug suspected of being responsible, according to serum levels of alanine aminotransferase （ALT）, alkaline phosphatase （ALP）, and total bilirubin （T-Bil）. However, as DILI patients may show resolution of liver injury without discontinuation of the drug, it should be carefully evaluated whether the suspected drug should be discontinued immediately with adequate consideration of the importance of the medication.

An Improved Method of Structure Damage Diagnosis for Jacket Platforms

In the exploitation of ocean oil and gas, many offshore structures may be damaged due to the severe environment, so an effective method of diagnosing structural damage is urgently needed to locate the damage and evaluate its severity. Genetic algorithms have become some of the most important global optimization tools and been widely used in many fields in recent years because of their simple operation and strong robustness. Based on the natural frequencies and mode shapes of the structure, the damage diagnosis of a jacket offshore platform is attributed to an optimization problem and studied by using a genetic algorithm. According to the principle that the structural stiffness of a certain direction can be greatly affected only when the brace bar in the corresponding direction is damaged, an improved objective function was proposed in this paper targeting measurement noise and the characteristics of modal identification for offshore platforms. This function can be used as fitness function of a genetic algorithm, and both numerical simulation and physical model test results show that the improved method may locate the structural damage and evaluate the severity of a jacket offshore platform satisfactorily while improving the robustness of evolutionary searching and the reliability of damage diagnosis.

Diagnosis and treatment of diffuse axonal injury in 169 patients

To evaluate current diagnosis and therapeutic effect and outcome of diffuse axonal injury （DAI） in 169 patients. Methods ： The data of 169 DAI patients treated in the Second, Sixth, Eighth and Ninth Hospitals of Shenzhen and Shekou Hospital from January 2001 to January 2005 were collected. The imaging features, classification, GCS （Glasgow coma scale）, treatment and outcome of the 169 patients were retrospecti.vely analyzed. Results ： The simpler the imaging features, the closer the focus of DAI to the periphery of hemisphere and the higher the GCS score, the better the prognoses of DAI patients will be. Conclusions： The prognoses of DAI patients are closely related to the imaging features and classification, GCS and clinical treatment.

Diagnosis and treatment of pancreatic trauma

Objective： To improve diagnosis and therapeutic efficacy for pancreatic trauma. Methods： We retrospectively analyzed 71 cases of pancreatic injuries received in our department from 1987 to 2004. Different surgical procedures were performed according to different patterns of pancreatic injuries. Among them, 31 cases were defined as Grade I or Ⅱ injury according to the pancreatic organ injury score developed by American Association for the Surgery of Trauma and were performed pancreas debridement and drainage; 26 cases belonged to Grade Ⅲ injury and were performed distal pancreatectomy plus external drainage; 10 cases of Grade IV injury in whom 8 were performed distal Roux-en-Y pancreaticojejunostomy and 2 were performed Whipple operation; 4 cases of Grade V injury in whom 1 was performed restoration of duodenal damage, suture of proximal pancreatic laceration and distal Roux-en-Y pancreaticojejunostomy, and 3 were performed Whipple operation. Results： Sixty-six cases were cured, of whom 14 had postoperative complications, and 5 cases died. The causes of death were of pancreatic fistula in 2 cases, upper gastrointestinal bleeding in 1 case, ARDS in 1 case, and serious abdominal infection in 1 case. Conclusions： Preoperative diagnosis for pancreatic trauma is rather challenging. Prompt explorative laparotomy is still a reliable diagnostic method for pancreatic trauma. In order to improve curative rate, different surgical procedures should be undertaken according to different sites and grades of pancreatic traumas.