Virtual Simulation for Multi-material LM Process

In an ONR funded MURI program, to improve quality of multi-material parts, we've been developing an advanced computer simulation for the multi-material layered manufacturing (LM) process. The CAD models and their .stLfiles are created using. the commercially available software such as I-DEAS and ProE. Using this information, one tool path file per material is generated. Our file preparation algorithm, systematically, layer by layer, integrates all tool path files into one multi-material tool path file. The results of the multi-material tool path are graphically visualized using the simulation algorithm (written in c++ & SGI OpenGL). From a virtual simulation, we can check the LM process, and make the best selection of tool path parameters afterwards. After several trials from design to simulation, if the simulation result is acceptable, the real manufacturing can be started. And the part's quality should be better than a part manufactured without running simulation in advance. This paper will represent .•. new studies on using real toadshapes to get more realistic simulation results. Many parts have been successfully simulated using our method.Mechanical Engineerin

Optimization Approach to Estimate Hammerstein–Wiener Nonlinear Blocks in Presence of Noise and Disturbance

Hammerstein–Wiener model is a block-oriented model where a linear dynamic system is surrounded by two static nonlinearities at its input and output and could be used to model various processes. This paper contains an optimization approach method for analysing the problem of Hammerstein–Wiener systems identification. The method relies on reformulate the identification problem; solve it as constraint quadratic problem and analysing its solutions. During the formulation of the problem, effects of adding noise to both input and output signals of nonlinear blocks and disturbance to linear block, in the emerged equations are discussed. Additionally, the possible parametric form of matrix operations to reduce the equation size is presented. To analyse the possible solutions to the mentioned system of equations, a method to reduce the difference between the number of equations and number of unknown variables by formulate and importing existing knowledge about nonlinear functions is presented. Obtained equations are applied to an instance H–W system to validate the results and illustrate the proposed method

Empathy in Iranian medical students: A preliminary psychometric analysis and differences by gender and year of medical school

Background: It has been well documented that effective empathic communication in the context of patient care is associated with improved health care outcomes. However, the emphasis given to empathy in medical education in Iran is limited, and the state of such teaching is unknown in many countries. Aims: To determine the psychometric properties of an Iranian translation of the Jefferson Scale of Physician Empathy (JSPE) among medical students, and to examine the differences on mean empathy scores by gender and the different years of medical school. Method: A cross-sectional study was conducted among medical students. Data analysis was based on 181 questionnaires. Principal component analysis (PCA) with Varimax rotation was used to identify the number and composition of components constituting the developed constructs. Results: The PCA yielded three factors: Compassionate care, perspective-taking, and the ability to walk in the patient's shoes. No statistically significant differences in the empathy means scores were found by gender and the different years of medical school. Conclusions: The Persian version of JSPE is a psychometrically sound instrument to measure empathy. Cultural backgrounds and pedagogical practice may influence medical students' attitudes towards empathy. Some recommendations are made, and the study limitations are discussed

A Rare Case of Gastrointestinal Tract Foreign Body; Glassy Stomach

Ingestion of foreign bodies is common and conservative treatment can eliminated most particlesfrom the gastrointestinal tractunless peritoneal signs appear. A 22-year-old man presented to emergency department who had ingested glass particles of a crushed beverage bottle. He complained of epigastric and periumbilical pain. Physical examination did not revealany peritoneal signs. Abdominal X-ray showed stomach full of small glass particles. Conservative treatment, without any surgical intervention,resulted insafely eliminating glass particlesin this patient

An investigation on the wound severity and its association with predisposing factors in patients with diabetic foot

Background and aims: Diabetic foot is the most common cause for hospitalization among diabetic patients whose treatment is costly in the world. In developed countries, over 5% of diabetic patients are involved in diabetic foot, and if it is not treated quickly and appropriately, it wil be led to blood infection, gangrene, and amputation. The present study aimed at investigating the wound severity and its association with predisposing factors in patients with diabetic foot. Methods: This is a descriptive analytic study in which 94 patients with diabetic foot, referring to governmental and non-governmental clinics in Isfahan, were selected through convenient sampling. Data were collected by a three-section questionnaire. The first section contained demographic characteristics, and the second was on wound severity based on Wagner scale. The third section was associated with wound formation predisposing factors. Data were analyzed by descriptive statistics and by SPSS software through Spearman correlation test, Kruskal Wallis and Mann-Whitney. Results: Wound severity, based on Wagner scale, was in grade two in most of diabetic food patients (75%). There is a significant association between wound severity and the factors such as BMI(P=0.041), smoking (P=0.041), FBS (0.026), two hour postprandial glucose (P=0.016), and wound depth (P=0.041). Conclusion: Based on the findings, diabetic food wound severity was moderate among the subjects and predisposing factors were FBS, 2-hour postprandial blood glucose, smoking, and wound depth. It is recommended to detect and modify these factors among the patients to prevent amputation and probable complications

Chitosan Preparation from Persian Gulf Shrimp Shells and Investigating the Effect of Time on the Degree of Deacetylation

Chitosan is an amino polysaccharide which can be prepared from shrimp shells with several applications in medicine and tissue engineering. The most important parameter, that characterizes chitosan and its applications, is its degree of deacetylation. In this research the influence of deacetylation time on the quality of the produced chitosan was investigated by measuring the amount of glucosamine and acetyl glucosamine. The amount of glucosamine in the sample was measured using HPLC analysis based on derivation method. By deacetylation of the extracted chitin in 90 and 180 minutes, chitosan with deacetylation degree of 69.75% and 77.63% was obtained, respectively. Therefore, by increasing the deacetylation period in a constant temperature condition and NaOH concentration, the deacetylation degree is increased

Experimental Study on the Effect of Fibers on Engineered Cementitious Composite Short Square Columns

Recent earthquakes severely damaged short columns due to high lateral stiffness and low ductility. Some conditions, such as reductions in the heights of some columns compared to others on the same floor, deep beams, partially buried basements, and non-structural walls, cause short column effects. The prominent characteristics of engineered cementitious composites (ECCs) reinforced with polyvinyl alcohol (PVA) fibers – including their high tensile strength, micro and multiple cracks, energy dissipation, high ductility, and strain hardening – lead to improved seismic performance and economic efficiency in structure elements. In this study, 11 ECC columns with different fiber fractions (0–1.5%) and aspect ratios (3–7), as well as one conventional concrete column, were tested and evaluated. The results showed that increasing fiber friction and shear aspect ratio increased the length of the plastic hinge zone and ductility by at least 50% and 100%, respectively. Furthermore, the failure mode changed from brittle shear to ductile shear

Investigating Nutritional Value of Bassia scoparia Seed in vitro for Ruminants Nutrition in Arid and Semi-Arid Regions

Introduction: Halophytes are plants with ability to survive in saline and alkaline soils and are drought resistant. In many areas of the world, native and introduced halophytes are forage resources, especially for sustaining grazing livestock when other feeds are scarce. Iran is a typical country of wide deserts and saline ecosystems and halophytes plays a major role in the halophytic and xerophytic vegetation of Iran. kochia is a drought-resistant annual plant that its cultivation is increasing in Iran. Due to the possibility of irrigating this plant with saline water, it can play an important role in providing the required feed to livestock in areas with saline soil and water by producing significant grains with high protein content. The aim of this study was to investigate effect of different levels of kochia seed in high concentrate diets on rumen fermentation.Materials and Methods: Dietary treatments included control diet (no kochia seed) and three diets levels containing 10, 20 and 30 % of ration DM kochia seed. In all treatments, soybean meal and wheat bran in the diet were substituted with kochia seed. Gas production and dual-flow continuous culture system were used in this study. In the gas production test, treatments arranged as complete randomized design. The amount of gas produced in the samples was recorded at different hours after incubation and the parameters of gas production, organic matter digestibility and metabolic energy were calculated. In the second experiment, eight dual-flow continuous culture fermenters (1320 ml) were used in two periods (7 days adaptation, 3 days sampling). In each period, fermenters were randomly assigned to treatments. Temperature (38.5°C) and liquid and (10%/h) solid (5%/h) dilution rates were kept constant in the fermenters. Anaerobic conditions were maintained by the infusion of N2 at a rate of 40ml/min. Treatments were randomly assigned to fermenters. Fermenters were fed daily with 97 g dry matter. During sampling days, collection vessels were maintained at 4ºC to impede microbial action. Solid and liquid effluents were mixed and homogenized for 1 min, and a 500ml sample was removed via aspiration. Upon completion of each period, effluent from the 3 days of sampling was composited and mixed within fermenter and homogenized for 1 min. Subsamples were taken for total N, ammonia-N, and VFA analyses. Data were analyzed using the GLM procedure of SAS. Fermenter and period were considered random effects. Comparisons between treatments were completed with Tukey’s test. Effects were considered significant at P<0.05.Results and Discussion: Inclusion of kochia seed in the diet increased gas production potential and amount of produced gas compared to the control diet. Increasing levels of kochia seed in the diet linearly increased metabolizable energy, organic matter digestibility and short chain fatty acid production. Low lignin content and high hemicellulose digestibility could be the main reasons behind higher metabolizable energy and organic matter digestibility observed in kochia containing diets. The observed increase in gas production potential as well as the volume of produced gas in kochia seed containing diets also supports that this feedstuff does not contain antinutritional factors with antimicrobial properties or the amount of these compounds in the grain is not significant. In the dual flow continuous culture study, dry matter digestibility linearly increased with increasing levels of kochia seed in the diet. Organic matter digestibility tended to increase using kochia seed in the diet (P =0.08). An increase in protein digestibility observed in treatments containing 20 and 30 % kochia seed compared to other treatments. Total VFA concentration increased linearly in diets containing kochia seed (P = 0.01). This finding could be the result of higher organic matter digestibility in kochia seed containing diets. Also, it has been suggested that higher rumen fiber digestibility or partial replacement of starch with a digestible cell wall can increase the total VFA concentration by increasing the population of fiber-degrading bacteria, a mechanism that is especially important in high-concentrate diets. Average ammonia nitrogen concentration, the concentration before feeding and 2 hours after feeding decreased in kochia containing diets compared to control diet. Despite the increase in crude protein digestibility in diets containing 20 and 30% kochia seed, the average ammonia nitrogen concentration in these treatments was lower compared to the control treatment. This finding can be the result of higher use of ammonia nitrogen in these treatments. The higher digestibility of dry matter and the tendency to increase the digestibility of organic matter by increasing level of kochia seed in the diet could support this idea.Conclusion: The results of this study showed that using kochia seed in the diet up to 30% of ration dry matter could support optimal rumen fermentation. Due to the low water requirement and the ability of kochia plant to grow in saline soils on the one hand and the desirable energy and protein content of kochia seeds on the other hand, this grain can be used as a suitable option to meet part of the feed needed for ruminants in saline areas. Limited information is available and more in vivo research is needed in this area