28 research outputs found

    Increasing the Range of Contemporary Artillery Projectiles

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    The study of increasing range of standard 122 mm artillery projectile was done mainly by changing the base drag of standard projectile using hollow base shape and base bleed unit. The drag reduction in the case of the projectile with base bleed was up to 20% compared to the standard projectile, and in the case of the hollow base projectile, the drag reduction reaches 8%. Optimisation of base drag reduction was done by using the computational fluid dynamics software (CFD). CFD analyses enable complete calculation of fluid parameters behind the projectile base and determination of base bleed burning gases influence on flow field. In that way, we determine the pressure on the projectile base in the case of projectile with hollow base or with base bleed. CFD computations give us relation between base drag reduction and characteristics of base bleed grain. Using the CFD results in the modified 6-degree of freedom (6-DOF) projectile trajectory model, we calculate ranges of projectiles. The verification of estimated range increase by projectile modification was done by comparison with experimental results obtained on firing range. Comparison of measured range and results from 3-D radar show good compatibility with theoretical results from the modified 6-DOF

    Biosorption Study of Zn(Ii), Cu(Ii), Pb(Ii) And Cd(Ii) Ions by Palm Leaves Activated Carbon

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    The aim of the present study is to investigate the efficiency of palm leaves activated carbon on the removal of lead (Pb), zinc (Zn), copper (Cu), and cadmium (Cd) from the aqueous solution. The effect of various process parameters such as pH (2 – 10), initial metal ion concentration (50 – 1000 mg/L), particle size (125, 500, 800 μm), and temperature (303, 313, 323 K) was studied using batch adsorption technique. Thermodynamic parameters were also evaluated. The maximum metal ion removal efficiency of 94.5, 94.1, 87.4, and 90.7% for Pb, Cd, Zn, and Cu, respectively, was reached at an optimum pH of 5, biosorbent dosage of 1.0 g, and initial metal ion concentration of 50 ppm. The Freundlich adsorption isotherm model best described the removal of metal ions on palm leaves activated carbon with high correlation coefficients (0.98 – 1.00). The adsorption process was found to be favorable since the intensity of adsorption, n lies within 1 to 10. The adsorption capacity values were 40.0, 38.3, 38.0, and 40.00 mg/g for lead (Pb), zinc (Zn), copper (Cu), and cadmium (Cd), respectively. The metal ion adsorption was also found to be endothermic in nature. The efficiency was increased with an increase in temperature implying the process should be performed at a controlled temperatur

    Prediction of direct normal irradiation using a new empirical sunshine duration-based model

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    In this work, we are interested in presenting a new approach allowing us to express the Direct Normal solar Irradiation (DNI) according to the sunshine duration essentially. This choice is justified by the fact that in addition to the sunshine, duration has a strong correlation with solar irradiation, it is measured in many radiometric stations. Some clear sky models with modifications developed exclusively here are made valid for all types of sky. The proposed model is compared with one of the intelligent models such as the Support Vector Regression (SVR) for daily data from Ghardaïa

    May Measurement Month 2018: a pragmatic global screening campaign to raise awareness of blood pressure by the International Society of Hypertension

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    Aims Raised blood pressure (BP) is the biggest contributor to mortality and disease burden worldwide and fewer than half of those with hypertension are aware of it. May Measurement Month (MMM) is a global campaign set up in 2017, to raise awareness of high BP and as a pragmatic solution to a lack of formal screening worldwide. The 2018 campaign was expanded, aiming to include more participants and countries. Methods and results Eighty-nine countries participated in MMM 2018. Volunteers (≥18 years) were recruited through opportunistic sampling at a variety of screening sites. Each participant had three BP measurements and completed a questionnaire on demographic, lifestyle, and environmental factors. Hypertension was defined as a systolic BP ≥140 mmHg or diastolic BP ≥90 mmHg, or taking antihypertensive medication. In total, 74.9% of screenees provided three BP readings. Multiple imputation using chained equations was used to impute missing readings. 1 504 963 individuals (mean age 45.3 years; 52.4% female) were screened. After multiple imputation, 502 079 (33.4%) individuals had hypertension, of whom 59.5% were aware of their diagnosis and 55.3% were taking antihypertensive medication. Of those on medication, 60.0% were controlled and of all hypertensives, 33.2% were controlled. We detected 224 285 individuals with untreated hypertension and 111 214 individuals with inadequately treated (systolic BP ≥ 140 mmHg or diastolic BP ≥ 90 mmHg) hypertension. Conclusion May Measurement Month expanded significantly compared with 2017, including more participants in more countries. The campaign identified over 335 000 adults with untreated or inadequately treated hypertension. In the absence of systematic screening programmes, MMM was effective at raising awareness at least among these individuals at risk

    Association of respiratory symptoms and lung function with occupation in the multinational Burden of Obstructive Lung Disease (BOLD) study

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    Background Chronic obstructive pulmonary disease has been associated with exposures in the workplace. We aimed to assess the association of respiratory symptoms and lung function with occupation in the Burden of Obstructive Lung Disease study. Methods We analysed cross-sectional data from 28 823 adults (≥40 years) in 34 countries. We considered 11 occupations and grouped them by likelihood of exposure to organic dusts, inorganic dusts and fumes. The association of chronic cough, chronic phlegm, wheeze, dyspnoea, forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1)/FVC with occupation was assessed, per study site, using multivariable regression. These estimates were then meta-analysed. Sensitivity analyses explored differences between sexes and gross national income. Results Overall, working in settings with potentially high exposure to dusts or fumes was associated with respiratory symptoms but not lung function differences. The most common occupation was farming. Compared to people not working in any of the 11 considered occupations, those who were farmers for ≥20 years were more likely to have chronic cough (OR 1.52, 95% CI 1.19–1.94), wheeze (OR 1.37, 95% CI 1.16–1.63) and dyspnoea (OR 1.83, 95% CI 1.53–2.20), but not lower FVC (β=0.02 L, 95% CI −0.02–0.06 L) or lower FEV1/FVC (β=0.04%, 95% CI −0.49–0.58%). Some findings differed by sex and gross national income. Conclusion At a population level, the occupational exposures considered in this study do not appear to be major determinants of differences in lung function, although they are associated with more respiratory symptoms. Because not all work settings were included in this study, respiratory surveillance should still be encouraged among high-risk dusty and fume job workers, especially in low- and middle-income countries.publishedVersio

    Global patient outcomes after elective surgery: prospective cohort study in 27 low-, middle- and high-income countries.

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    BACKGROUND: As global initiatives increase patient access to surgical treatments, there remains a need to understand the adverse effects of surgery and define appropriate levels of perioperative care. METHODS: We designed a prospective international 7-day cohort study of outcomes following elective adult inpatient surgery in 27 countries. The primary outcome was in-hospital complications. Secondary outcomes were death following a complication (failure to rescue) and death in hospital. Process measures were admission to critical care immediately after surgery or to treat a complication and duration of hospital stay. A single definition of critical care was used for all countries. RESULTS: A total of 474 hospitals in 19 high-, 7 middle- and 1 low-income country were included in the primary analysis. Data included 44 814 patients with a median hospital stay of 4 (range 2-7) days. A total of 7508 patients (16.8%) developed one or more postoperative complication and 207 died (0.5%). The overall mortality among patients who developed complications was 2.8%. Mortality following complications ranged from 2.4% for pulmonary embolism to 43.9% for cardiac arrest. A total of 4360 (9.7%) patients were admitted to a critical care unit as routine immediately after surgery, of whom 2198 (50.4%) developed a complication, with 105 (2.4%) deaths. A total of 1233 patients (16.4%) were admitted to a critical care unit to treat complications, with 119 (9.7%) deaths. Despite lower baseline risk, outcomes were similar in low- and middle-income compared with high-income countries. CONCLUSIONS: Poor patient outcomes are common after inpatient surgery. Global initiatives to increase access to surgical treatments should also address the need for safe perioperative care. STUDY REGISTRATION: ISRCTN5181700

    Cohort Profile: Burden of Obstructive Lung Disease (BOLD) study

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    The Burden of Obstructive Lung Disease (BOLD) study was established to assess the prevalence of chronic airflow obstruction, a key characteristic of chronic obstructive pulmonary disease, and its risk factors in adults (≥40 years) from general populations across the world. The baseline study was conducted between 2003 and 2016, in 41 sites across Africa, Asia, Europe, North America, the Caribbean and Oceania, and collected high-quality pre- and post-bronchodilator spirometry from 28 828 participants. The follow-up study was conducted between 2019 and 2021, in 18 sites across Africa, Asia, Europe and the Caribbean. At baseline, there were in these sites 12 502 participants with high-quality spirometry. A total of 6452 were followed up, with 5936 completing the study core questionnaire. Of these, 4044 also provided high-quality pre- and post-bronchodilator spirometry. On both occasions, the core questionnaire covered information on respiratory symptoms, doctor diagnoses, health care use, medication use and ealth status, as well as potential risk factors. Information on occupation, environmental exposures and diet was also collected

    Optimization of artillery projectiles base drag reduction using hot base flow

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    The CFD numerical simulations were carried out to investigate the base drag characteristics of a projectile with base bleed unit with a central jet. Different base bleed grain types with different combustion temperatures were used. The goal was to find a way to effectively control the base flow for base drag reduction and optimisate the latter using an adequate CFD software. Axisymmetric, compressible, mass-averaged Navier-Stokes equations are solved using the k-ω SST, transition k-kl-ω, and RSM turbulence models. The various base flow characteristics are obtained by the change in the non-dimensionalized injection impulse. The results obtained through the present study show that there is an optimum bleed condition for all base bleed grains tested. That optimum is dependent on the temperature of the grain combustion products. The optimum reduces the total drag for 6,9% in the case of air injection at temperature of 300 K and reaches up to 28% in the case of propellant combustion products injection at almost 2500 K. Besides, the increasing of molecular weight has a role no less important than temperature of the combustion products in terms of base drag reduction

    Effectiveness of an educational program on nurses’ practice toward physical therapy for patients with COVID-19

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    This study aims to evaluate the effectiveness of an interventional program on nursing staffs’ practice toward physical therapy for patients with COVID-19. A pre-experimental (one-pretest-posttest) design was used to conduct this study. A non-probability (purposive) sampling was used to select (60 nurses) working in ICU. To measure the effectiveness of the interventional program, the researcher used a knowledge form that included (22) questions patient-oriented with COVID-19. The validity of the questionnaire and the interventional program was verified by presenting it to (12) experts. The reliability was determined using the test-retest approach for the knowledge questionnaire. Data analysis was done using the Statistical Package of Social Sciences (SPSS) version 25. The study findings statistical mean of the overall nursing staff' practices in physical therapy was (1.005), p. value (.320) before implementation of the interventional program, while it becomes (12.483), P. value (0.000) High significant  after the interventional program has been applied. When comparing the results of the study group before and after the implementation of the program, the results were statistically significant with a percentage of (9.834) P. value (0.000)
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