Critical speed and limit cycles in the empty Y25-freight wagon

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.In this research, an empty freight wagon with Y25 bogies have been modelled. Non-linear creep forces with spin moment between wheel and rail have been used, and also all impacts and friction forces have been modelled. Non-linear equations of motion and kinematical constraints have been solved in time domain, and limit cycles, saddle nodes, and critical speeds have been shown. Both primary and secondary hunting can be seen in the responses of the wagons. The relation between frequency of oscillations and speed can be seen, also, there are chaotic oscillations. Results show that stiffness in impacts affects calculation time and limit cycles

Algorithmic aspects of transient heat transfer problems in structures

It is noted that the application of finite element or finite difference techniques to the solution of transient heat transfer problems in structures often results in a stiff system of ordinary differential equations. Such systems are usually handled most efficiently by implicit integration techniques which require the solution of large and sparse systems of algebraic equations. The assembly and solution of these systems using the incomplete Cholesky conjugate gradient algorithm is examined. Several examples are used to demonstrate the advantage of the algorithm over other techniques

Effect of suspension system in the lateral stability of railway freight trucks

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.In the current research an empty freight wagon with BA652 and an old BA661 bogies have been modelled. Non-linear creep forces with spin moment between wheel and rail have been used and also all impacts and friction forces have been modelled. The characteristics of primary suspension systems for BA652 and an old BA661 have been evaluated by means of test. Non-linear equations of motions and kinematical constraints have been solved in time domain and limit cycles have been showed. Both primary and secondary hunting can be seen in responses of wagon. For BA652 there are non-linear and linear critical speeds and also saddle nodes but for old BA661 the situation is too critical and the system can oscillate in very low speeds

Recombinant erythropoietin and blood transfusion in very low birth weight infants

Background: Very low birth weight infants (<1500 g) frequently require blood transfusions because of repeated blood sampling accompanied by anemia of prematurity. Methods: In an attempt to identify the effect of human recombinant erythropoietin to decrease the requirement for blood transfusions, erythropoietin was administered to 24 preterm infants less than 1500 g prospectively from September 1999 till December 2000. Data about the characteristics of the population, the severity of diseases, and treatment with erythropoietin, clinical diagnosis, initial and subsequent hemoglobin, volume of blood loss, and the number of blood transfusions were recorded. These results were compared with data from the recorded information of 49 infants who did not receive erythropoietin during those past 2 years. There were no differences between the 2 groups with regard to the gestational age, birth weight, clinical diagnosis, severity of the illness, primary causes of admission, and initial hematologic parameters such as hemoglobin, hematocrit and reticulocytes. Erythropoietin was administered in a dose of 200 IU/kg three times weekly for 6-8 weeks accompanied with iron supplement 6 mg/kg/day. Transfusions were administered according to protocol. Results: There was no significant difference between the number of blood transfusion among these 2 groups (p=0.07). However, transfusions in the erythropoietin treated group were fewer in comparison to the other group (1.9 +/- 1.6 to 3.2 +/- 1.1). No difference was observed between final hemoglobin and hematocrit levels among the two groups (10.3 +/- 0.9 vs. 10.4 +/- 0.7 and 33.7 +/- 2.3 vs. 32.2 +/- 2.2). Conclusion: Very low birth weight infants receive frequent blood transfusions but a reduction in transfusion requirements was not apparent after administration of erythropoietin and iron in preterm infants in this study. However, the lack of impact on transfusion requirements fails to support routine use of erythropoietin

Does routine repeat testing of critical laboratory values improve their accuracy?

Background: Routine repeat testing of critical laboratory values is very common these days to increase their accuracy and to avoid reporting false or infeasible results. We figure that repeat testing of critical laboratory values has any benefits or not. Methods: We examined 2233 repeated critical laboratory values in 13 different hematology and chemistry tests including: hemoglobin, white blood cell, platelet, international normalized ratio, partial thromboplastin time, glucose, potassium, sodium, phosphorus, magnesium, calcium, total bilirubin and direct bilirubin. The absolute difference and the percentage of change between the two tests for each critical value were calculated and then compared with the College of American Pathologists/Clinical Laboratory Improvement Amendments allowable error. Results: Repeat testing yielded results that were within the allowable error on 2213 of 2233 specimens (99.1). There was only one outlier (0.2) in the white blood cell test category, 9 (2.9) in the platelet test category, 5 (4) in the partial thromboplastin time test category, 5 (4.8) in the international normalized ratio test category and none in other test categories. Conclusion: Routine, repeat testing of critical hemoglobin, white blood cell, platelet, international normalized ratio, partial thromboplastin time, glucose, potassium, sodium, phosphorus, magnesium, calcium, total bilirubin and direct bilirubin results does not have any benefits to increase their accuracy

Developing a fuzzy expert system to predict the risk of neonatal death

Introduction: This study aims at developing a fuzzy expert system to predict the possibility of neonatal death. Materials and Methods: A questionnaire was given to Iranian neonatologists and the more important factors were identified based on their answers. Then, a computing model was designed considering the fuzziness of variables having the highest neonatal mortality risk. The inference engine used was Mamdani's method and the output was the risk of neonatal death given as a percentage. To validate the designed system, neonates' medical records real data at a Tehran hospital were used. MATLAB software was applied to build the model, and user interface was developed by C# programming in Visual Studio platform as bilingual (English and Farsi user interface). Results: According to the results, the accuracy, sensitivity, and specificity of the model were 90, 83 and 97, respectively. Conclusion: The designed fuzzy expert system for neonatal death prediction showed good accuracy as well as proper specificity, and could be utilized in general hospitals as a clinical decision support tool. ©2016 Reza Safdari, Maliheh Kadivar, Mostafa Langarizadeh, Ahmadreaza Farzaneh Nejad, Farzaneh Kermani

Missing elements in surgical pathology reports: Breast, Colon and Stomach Cancers

Cancer pathology reports play an important role in choice of patient care. They provide crucial information concerning diagnosis, therapy options, and prognosis. Professional pathology institutions, such as the College of American Pathologists (CAP), have developed checklists to ensure the presence of all the required elements in reports. In this study, 438 surgical pathology reports of patients with breast (148), colon (147), and stomach cancer (143) were evaluated with respect to the presence of mandated elements according to CAP checklists. The most common missing element in all the three types of cancer was 'staging' (73.6, 53.1, and 56.6 in breast, colon, and stomach cancer reports missed 'staging', respectively). The second most missing element was 'tumor site' in breast (64.2) and stomach cancer (30.1), and 'procedure' in colon cancer (29.3). 'Perineural invasion' was the third most missing element in the three types of cancer (25.7, 17.0, and 22.4 in breast, colon, and stomach cancer, respectively). Only 11.4 of reports included all key elements required by CAP. The use of checklists was associated with higher rate of completeness. This study demonstrates that the key elements requiring the information on the requisition forms from the clinicians are commonly missed, leading to ambiguity

Histological effect of cola nitida aqueous extract on rat's liver during hepatocarcinogenesis.

Hepatocarcinogenesis can be defined as precancerous lesion which will develop into Hepatocellular Carcinoma. It has been carried out previously that Cola nut (Cola nitida) has beneficial medicinal properties. In this study, we have assumed efforts to ascertain the histological anticancer potency of Cola Nitida aqueous extract on DEN/AAF induced hepatocarcinogenesis rat's liver. The structural components of the liver include plates of liver, called hepatocytes. The normal hepatocytes were well organized and arranged. Cells membranes were markedly clear. The nuclei were round and uniform with little variation in size causing no pleomorphis. Male Sprague Dawley rats were divided to eleven groups. Hepatocarcinogenesis was induced in seven groups of rats by employing two carcinogen systems: an intraperitoneal injection of 200 mg/kg DEN as initiator, followed by 0.02% of AAF in rat chow to promote carcinogenesis. The effect of 1, 2.5 and 5% cola nitida aqueous extract on hepatocarcinogenesis induced male rats and normal ones was investigated. Histological evaluation of rat liver revealed DEN/AAF induced and untreated rats group showed higher inflammation or necrosis, and in general abnormality; compared to all other groups. The results indicate that, Cola nitida might act as an antioxidant agent, which could inhibit or slow down histopathological changes induced by DEN/AAF

Concurrent diagnosis of infective endocarditis and acute rheumatic fever: A case report

Rheumatic heart disease has been classically considered as a risk factor for infective endocarditis (IE). Although valvulitis is frequently present in patients with acute rheumatic fever (ARF), the established valve disease after initial episode of ARF is usually considered as a predisposing factor for IE. We hereby present a biopsy-proven case of IE co-diagnosed with the first episode of ARF. © 2018 Japanese College of Cardiolog