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排序方式: 共有298条查询结果,搜索用时 15 毫秒
21.
Mustafa Turan Ferhat Gunay Adil Aslan 《Journal of Intelligent and Robotic Systems》2012,65(1-4):73-91
Unmanned Aircraft (UA) have become an integral part of the present-day joint air operations. UA have potential to be employed across the full spectrum of Air Force functions. On the other hand, UA technology could be a subject of an asymmetric use by state actors in high or low density conflict, and/or by non-state actors in many ways including terrorism, drug smuggling, and limited attack with unconventional payloads i.e. biological or chemical agents. Therefore countering the threat associated with the hostile UA use could be necessary in the future. First part of the research revealed that UA can be a threat in the future. In the second part of the research, the SWOT (Strengths-Weaknesses-Opportunities-Threats) analysis supplemented with the Tree analysis (SWOT+Tree) provided a broader look for investigating the factors related to hostile UA use analytically. In literature, there is little information about the concepts for CUAOPS. The final goal of the paper is to find possible solutions and means for a better understanding of the nature of CUAOPS. 相似文献
22.
Can an electronic portfolio that is both a multimedia container for student work and a tool to support key learning processes have a positive impact on the literacy practices and self-regulated learning skills of students? This article presents the findings of a yearlong study conducted in three Canadian provinces during the 2007–2008 school year initially involving 32 teachers and 388 students. Due to varying levels of implementation our final data set included 14 teachers and 296 students. Using a non-equivalent pre-test/post-test design, we found that grade 4–6 students who were in classrooms where the teacher provided regular and appropriate use of the electronic portfolio tool ePEARL (i.e., medium–high implementation condition, n = 7 classrooms and 121 students), compared to control students (n = 7 classrooms and 175 students) who did not use ePEARL, showed significant improvements (p < .05) in their writing skills on a standardized literacy measure (i.e., the constructed response subtest of the Canadian Achievement Test-4th ed.) and certain metacognitive skills measured via student self-report. The results of this study indicate that teaching with ePEARL has positive impacts on students’ literacy and self-regulated learning skills when the tool is used regularly and integrated into classroom instruction. 相似文献
23.
A promising line of research for radar systems attempts to optimize the detector thresholds so as to maximize the overall performance of a radar detector–tracker pair. In the present work, we attempt to move in a direction to fulfill this promise by considering a particular dynamic optimization scheme which relies on a non-simulation performance prediction (NSPP) methodology for the probabilistic data association filter (PDAF), namely, the modified Riccati equation (MRE). By using a suitable functional approximation, we propose a closed-form solution for the special case of a Neyman–Pearson (NP) detector. The proposed solution replaces previously proposed iterative solution formulations and results in dramatic improvement in computational complexity without sacrificed system performance. Moreover, it provides a theoretical lower bound on the detection signal-to-noise ratio (SNR) concerning when the whole tracking system should be switched to the track before detect (TBD) mode. 相似文献
24.
Ersin Çelik MD Ahmet Rıfkı Çora MD 《Hemodialysis international. International Symposium on Home Hemodialysis》2023,27(1):E12-E14
Cuffed-tunneled hemodialysis catheter (CTHC) application via the femoral vein is a safe and effective alternative when peripheral vascular routes are exhausted for hemodialysis in patients with end-stage renal disease. Also, imaging methods have become more important for the diagnosis or prevention of the possible complications that may develop during or after catheter placements. Here, we present a case of hemodialysis catheter dysfunction due to the insertion of a CTHC tip into the hepatic vein, and into the left ascending lumbar vein at the next attempt. We think that the use of fluoroscopy, whether in the first catheter intervention or catheter change, is extremely important in preventing possible complications that may develop, or detecting them as soon as possible. 相似文献
25.
Fecal indicators such as Escherichia coli and enterococci are used as regulatory tools to monitor water with 24 h cultivation techniques for possible input of sewage or feces and presence of potential enteric pathogens yet their source (human or animal) cannot be determined with routine methods. This critical uncertainty has furthered water pollution science toward new molecular approaches. Members of Bacteroides genus, such as Bacteroides thetaiotaomicron are found to have features that allow their use as alternative fecal indicators and for Microbial Source Tracking (MST). The overall aim of this study was to evaluate the concentration and fate of B. thetaiotaomicron, throughout a wastewater treatment facility and septage treatment facility. A large number of samples were collected and tested for E. coli and enterococci by both cultivation and qPCR assays. B. thetaiotaomicron qPCR equivalent cells (mean: 1.8 × 107/100 mL) were present in significantly higher concentrations than E. coli or enterococci in raw sewage and at the same levels in raw septage. The removal of B. thetaiotaomicron target qPCR signals was similar to E. coli and enterococci DNA during the treatment of these wastes and ranged from 3 to 5 log10 for wastewater and was 7 log10 for the septage. A significant correlation was found between B. thetaiotaomicron marker and each of the conventional indicators throughout the waste treatment process for both raw sewage and septage. A greater variability was found with enterococci when compared to E. coli, and CFU and equivalent cells could be contrasted by various treatment processes to examine removal and inactivation via septage and wastewater treatment. These results are compared and contrasted with other qPCR studies and other targets in wastewater samples providing a view of DNA targets in such environments. 相似文献
26.
Pain is one of the most troublesome complications of tonsillectomy. The pain appears as throat pain, otalgia, or both, and continues until mucosal recovery on the tonsillar fossae is complete. Some surgical and hemostasis techniques may increase pain. Analgesics, antibiotics, steroids, and local and topical anesthetics are used to relieve posttonsillectomy pain, but none has the desired effectiveness. The pain reliever must not increase bleeding and must have minimal side effects. Sucralfate, a basic amino salt of sucrose octasulfate, binds to the matrix protein of a peptic ulcer and produces a protective barrier. Tonsillectomy leaves two large ulcerous wounds, and sucralfate may bind those wounds as it does peptic ulcers. In this controlled study, the efficacy of sucralfate on posttonsillectomy throat pain, otalgia, analgesic requirement, degree of strength, bleeding, body temperature, and mucosal recovery is investigated in 80 patients. Sucralfate is found to significantly reduce throat pain and analgesic requirement after surgery. 相似文献
27.
Gizem Yanalak Abdalaziz Aljabour Emre Aslan Faruk Ozel Imren Hatay Patir 《International Journal of Hydrogen Energy》2018,43(36):17185-17194
The efficiencies of a series of hydrogen evolving catalysts based on metal oxide nanofibers (NiO, Co3O4, Mn3O4) are investigated for the photocatalytic hydrogen evolution from water without using any co-catalyst under the visible light irradiation by using triethanolamine (TEOA) as an electron donor and Eosin-Y (EY) dye as a photosensitizer. It is found that the photocatalytic hydrogen evolution activities follow the order as: Mn3O4<Co3O4<NiO (196 μmolg?1h?1, 5552 μmolg?1h?1, 7757 μmolg?1h?1, respectively). Moreover, the catalytic behavior of these nanofibers on the hydrogen production has been also compared to bulk forms of NiO, Co3O4 and Mn3O4 by producing hydrogen 937 μmolg?1h?1, 901 μmolg?1h?1 and 135 μmolg?1h?1, respectively. The nanofiber structures demonstrated much higher photocatalytic activity than bulk forms due to the effect of the increased surface to volume ratio deduced from the fibrous character. The photocatalytic plausible pathway for the hydrogen production is also discussed. 相似文献
28.
Mustafa Aslan 《Energy Sources, Part A: Recovery, Utilization, and Environmental Effects》2016,38(14):2072-2078
Hydrogen gas is an ideal alternative fuel and produces no greenhouse gases. The dark fermentation is considered the most attractive for production of biohydrogen gas. Duckweed is an aquatic plant that has treatment properties and can be used as biomass for the fermentation to produce eventually bio-hydrogen production. This study investigated the impact of different temperature, pH, and substrate concentration on bio-hydrogen production by fermentation. Experimental tests were run flask studies in serum bottles by aim of determing the optimal operating conditions to maximize bio-hydrogen production. According to the results, concentration loading in the range 30–40 g DW/L was determined as suitable for efficient bio-hydrogen production. Different temperatures on bio-hydrogen production were compared, and 35°C was observed to be more effective than others. Moreover, pH 5.5 was determined as the optimal pH value. 相似文献
29.
Sema Aslan Necdet Aka 《Energy Sources, Part A: Recovery, Utilization, and Environmental Effects》2019,41(3):290-297
NaOH/sepiolite nanocomposite heterogenous base catalyst (NaOH/sep.) was prepared via impregnation process and tested in a three-neck flask equipped with thermometer and reflux condenser for the production of biodiesel from transesterification of canola oil in an excess amount of methanol. The ratio of NaOH and sepiolite was selected as 1:4. The influence of various operational parameters was examined such as methanol to oil molar ratio, catalyst dosage, and reaction temperature. Untreated sepiolite and NaOH loaded sepiolite were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Scanning electron microscopy and Energy dispersive spectroscopy analysis. Overall NaOH/sep. based biodiesel production yield was examined by the help of Gas chromatography-mass spectrometry analysis. The yield was calculated from the peak areas as 80.93% which is better than that of expensive catalysis system using studies. 相似文献
30.
Enhanced heat transfer and pressure loss in a tube with loose-fit perforated twisted tapes were experimentally investigated. The effects of the twist ratio and the hole diameter ratio were also described. A constant twisted tape width of 52 mm, which is lower than the tube inside diameter of 56 mm, was used in order to reduce excessive pressure drops associated with full-width twisted tape elements. The tests were conducted using the tapes with three different ratios of pitch length of twisted tape to inner diameter of tube (twist ratios = 2, 2.5, 3) and three different ratios of hole to inner diameter (diameter ratios = 0.0714, 0.107, 0.143) in a range of Reynolds number 4860 to 24,130 under uniform heat flux conditions. The experimental findings revealed that the Nusselt number, friction factor, and thermal performance factor increase with decreasing twist ratio and hole diameter ratio. The maximum value of thermal performance factor of 1.27 was achieved for the case at a twist ratio of 2 and a hole diameter ratio of 0.0714. Eventually, the experimental results of Nusselt number, friction factor and thermal performance factor were correlated, and the deviations determined for Nusselt number, friction factor, and thermal performance factor were within ±7%, ±8%, and ±6%, respectively. 相似文献