599 research outputs found

    Weight–strength optimization of wooden household chairs based on member section size

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    Weight-strength optimization of wooden household chairs was performed based on the member section size in this study. Member section sizes of the Scotch pine (Pinus sylvestris) and Oriental beech (Fagus orientalis) chairs were optimized and resulting re-manufactured optimized chairs were tested under the cyclic “front to back”, “back to front” and “backrest” loads according to American Library Association (ALA) specification. Finite element method (FEM) and MATLAB nonlinear programming were utilized for the optimization. Firstly, the internal forces and moments acting on each member were analyzed by FEM in order to obtain the maximum critical stresses in each type of member; then, optimized cross-sectional sizes of the members were determined by Gradient Descent method, and all constraints were treated with Logarithmic Barrier Functioning. As a result, the minimum section sizes of members were determined, and cyclic performance tests were performed to determine whether the optimized chairs were strong enough to carry the acceptable loads. According to the results, member section size of both beech and pine chairs could be significantly reduced. The reduction was 32 % in the total weight and volume for beech chairs while 16 % for pine chairs without sacrificing the performance required for domestic usage by ALA. In conclusion, the method used is suitable for the optimization of furniture frames, making it lighter and reducing the material costs.&nbsp

    PHOTOGRAMMETRIC APPROACH IN DETERMINING BEAM-COLUMN CONNECTION DEFORMATIONS

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    In accordance with the advances in technology, displacement calculation techniquesare ever developing. Photogrammetry has become preferable in some newdisciplines with the advances in the image processing methods. In this study, theauthors have used two different measurement techniques to determine the angles ofrotation in beam-column connections that are subjected to reversible cyclic loading.The first of these is the method that is widely used, the conventional method instructural mechanics experiments, where Linear Variable Differential Transformers(LVDTs) are utilized; and the second is the photogrammetric measurementtechnique. The rotation angles were determined using these techniques in a total often steel beam-column connection experiments. After discussing the test proceduresof the aforementioned methods, the results were presented. It was observed that therotation angles measured by each method were very close to each other. It wasconcluded that the photogrammetric measurement technique could be used as analternative to conventional methods, where electronic LVDTs are used

    B12 Vitamin and Folat Prevelance of Children and Adolescents in Diyarbakır

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    The most common cause of megaloblastic anemia in childhood are vitamin B12 and folat deficiency. Folat and vitamin B12 play a role in DNA synthessis in gastrointestinal, urogenital,nerves and hemotopoetic cells. The diagnosis of megaloblastic anemia is easy and the treatment cost is low.In this study, the prevalence of vitamin B12 and folat deficiencies in 889 students were determined. Vitamin B12 and folat levels in blood samples were measured via RİAThe average age were betwen 12 and 22 years. Of this students 294(%33,1) were female and 595 (%66,9) were male. The incidence of vitamin B12 deficiency was found to be 2.2%, while folat deficiency was 21.8%. The mean vitamin B12 level was 331,51±144,05 pg/mL (325,60±138,91 in pg/mL male, 343,48±153,48 pg/mL in female), the mean folat level was 5,42±2,12 ng/ml (5,23±2,11 ng/ml in male, 5,80±2,10 ng/ml in female).The prevelance of folat deficiency in our region was higher than other countries, possibly due to low socioeconomical status, improper or inadequate food intake and low educational status

    Pseudoperikarditis krave uzrokovan tajleriozom.

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    Pseudopericarditis has been used to describe jugular engorgement and oedema of the brisket and ventral abdominal wall. Similar symptoms can be seen in cattle with traumatic pericarditis. Pressure caused by tumours, abscesses, Echinococcus cysts, swollen lymph nodes resulting from tuberculosis and leukosis, one-sided pleuritis and diaphragmatic hernia to the base of cranial and caudal vena cava returning blood to the heart have been reported to cause pseudopericarditis in cattle. These mediastinal lymph nodes may also be swollen due to theileriosis and cause pressure on the v. cava. This study aims to describe the clinical, haematological and electrocardiographical findings of a pseudopericarditis case in a cow caused by theileriosis, and to add the disease into the aetiology of pseudopericarditis.Opisan je pseudoperikarditis kod zastoja u jugularnoj veni te edema prsišta i ventralne abdominalne stijenke. Slični simptomi mogu se zabilježiti u goveda kod traumatskog perikarditisa. Pritisak uzrokovan tumorima, apscesima, hidatidnim cistama, povećanim limfnim čvorovima kod tuberkuloze i leukoze, jednostranim pleuritisom te dijafragmatskom hernijom prema bazi kranijalne i kaudalne šuplje vene već su opisani kod pseudoperikarditisa u goveda. Medijastinalni limfni čvorovi mogu biti povećani i kod tajlerioze te pritisnuti šuplju venu. Opisani su klinički, hematološki i elektrokardiografski nalazi kod pseudoperikarditisa u krave uzrokovanog tajleriozom čime je povećan niz uzroka koji dovode do navedene bolesti

    Influence of mix design variables on engineering properties of carbon fiber-modified electrically conductive concrete

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    This research was inspired by the need to optimize the mix design of electrically conductive concrete (ECON) for field implementation. Carbon fiber was used for producing ECON with different mixing proportions and constituents. Calcium nitrite-based corrosion inhibitor admixture and methylcellulose were used as conductivity-enhancing agent (CEA) and fiber-dispersive agent (FDA) respectively. Five easy-to-change mix design variables were evaluated for their effects on electrical conductivity and strength of ECON: carbon fiber dosage, fiber length, coarse-to-fine aggregate volume ratio (C/F), CEA dosage, and FDA dosage. The results approved the effectiveness of the applied CEA in improving electrical conductivity while positively influencing strength. Conductivity was significantly influenced by: fiber content, C/F, fiber length, and CEA dosage. The dosages of Fiber, CEA, and FDA exerted significant influence on compressive strength. C/F and FDA dosage were significant variables influencing flexural strength
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