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排序方式: 共有1939条查询结果,搜索用时 13 毫秒
41.
In this investigation, biogas (BG) was used as an alternative fuel in a single-cylinder, four-stroke, air-cooled, direct injection (DI) diesel engine that was operated on a dual fuel mode. Biogas was produced from a non-edible seed de-oiled cake-pongamia pinnata (Karanja), which was collected from the biodiesel industries. The BG was inducted along with the air in suction of the engine at four different flow rates varying from 0.3?kg/h to 1.2?kg/h in steps of 0.3?kg/h. The investigation results revealed that BG inducted at a flow rate of 0.9?kg/h gives better combustion characteristics of engine behaviour than those of other flows throughout the engine operation. The ignition delay (ID) and combustion duration of the engine run by dual fuel operation at a BG flow rate of 0.9?kg/h were found to be longer by about 2 °CA and 2.9 °CA, respectively, in comparison with diesel at full load. The cylinder peak pressure was found to be overall higher by about 11?bar than that of diesel at full load. 相似文献
42.
43.
Murugan Arunachalam Sabeenian Royappan Savarimuthu 《International journal of imaging systems and technology》2019,29(1):65-76
In recent years, mortality rate with high-grade tumor has been increased significantly especially with glioblastoma (GBM) brain tumor while compared to other malignant brain tumor. Here, the amount of dead cells accommodated with the tumor tissue in GBM brain tumor play a vital task and necessitate an earlier diagnosis of malignancy with the GBM tumor. It inspires to implement new automatic diagnosis system which detects the dead cells and tumor tissue with the GBM brain tumor, such that the survival rate of the diseased can easily be prognosis by the Radiologist and Neurosurgeon. The main objective of this article is to detect the amount of dead cells with respect to tumor tissue associated with the GBM brain tumor which desires the impact factor of the brain tumor. In this framework, initially, the new contrast enhancement modality is incorporated to enhance the gray information over the dead cells and the tumor tissue with the T1-weighted MRI GBM brain tumor. In this enhancement, the edges of the tumor cells and its dead cells are magnified efficiently. As the noises and outliers with MR image is unpredictable and it experiences the variable amount of noises over the local window, the contextual information over each pixel of the image is adaptively modified with respect to the amount of noise over local window using adaptive contextual clustering. The performance evaluation of the framework is investigated which exhibits the overwhelming result compared to conventional detection techniques. 相似文献
44.
Recently, Packet scheduling plays a vital role in Wireless Sensor Networks (WSNs). The major key challenges include delay, packet dropping, energy consumption and lifetime due to constraints in energy and computing resources. All the research works on packet scheduling scheme in WSN uses only First Come First Served (FCFS) and Dynamic Multilevel Priority (DMP) schemes. FCFS works based on packet arrival time, it leads to starvation and high processing overhead for real-time packets. DMP works in multilevel with dynamic priority reduces the transmission overhead and bandwidth; it consumes more resources for real-time task leads to deadlock. To solve these problems, this work presents Multilevel Dynamic Feedback Scheduling (MDFS) algorithm. The sensor node classifies the emergency and normal data into three different ready queues named as high, medium and low priority, respectively. The queues are connected with a feedback mechanism; each packet from the sensor node has its own time quantum value based on the deadline. The updated time quantum value is compared with the boundary value of the queues, depends on the updated value the data packets are moved between queues with help of feedback mechanism. The simulation result proves that the projected MDFS outperforms in WSN environment. 相似文献
45.
46.
Open dumping site in Asian developing countries: a potential source of polychlorinated dibenz-p-dioxins and polychlorinated dibenzofurans 总被引:1,自引:0,他引:1
Nguyen HM Tu BM Watanabe M Kunisue T Monirith I Tanabe S Sakai S Subramanian A Sasikumar K Pham HV Bui CT Tana TS Prudente MS 《Environmental science & technology》2003,37(8):1493-1502
Open landfill dumping areas for municipal wastes in Asian developing countries have recently received particular attention with regard to environmental pollution problems. Because of the uncontrolled burning of solid wastes, elevated contamination by various toxic chemicals including dioxins and related compounds in these dumping sites has been anticipated. In this study, concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and coplanar polychlorinated biphenyls (PCBs) were determined in soils from dumping sites in the Philippines, Cambodia, India, and Vietnam. Residue concentrations of PCDD/Fs and coplanar PCBs in dumping site soils were apparently greater than those in soils collected in agricultural or urban areas far from dumping sites, suggesting that dumping sites are potential sources of PCDD/Fs and related compounds. Observed PCDD/F concentrations in soils from dumping sites in the Philippines and Cambodia were comparable or higher than those reported for dioxin-contaminated locations in the world (e.g., near the municipal waste incinerators and open landfill dumping sites). Homologue profiles of PCDD/Fs in dumping site soils from the Philippines and, to a lesser extent, from Cambodia and India reflected patterns of samples representing typical emissions, while profiles of agricultural or urban soils were similar to those of typical environmental sinks. This result suggests recent formation of PCDD/Fs in dumping site areas and that open dumping sites are a potential source of dioxins in Asian developing countries. Uncontrolled combustions of solid wastes by waste pickers, generation of methane gas, and low-temperature burning can be major factors for the formation of dioxins in dumping sites. Elevated fluxes of PCDD/Fs to soils in dumping sites were encountered in the Philippines, Cambodia, India, and Vietnam-Hanoi, and these levels were higher than those reported for other countries. Considerable loading rates of PCDD/Fs in the dumping sites of these countries were observed, ranging from 20 to 3900 mg/yr (0.12-35 mg TEQ/yr). PCDD/F concentrations in some soil samples from the Philippines, Cambodia, India, and Vietnam-Hanoi exceeded environmental guideline values, suggesting potential health effects on humans and wildlife living near these dumping sites. The estimated intakes of dioxins via soil ingestion and dermal exposure for children were higher than those for adults, suggesting greater risk of dioxin exposure for children in dumping sites. To our knowledge, this is the first comprehensive study on PCDD/Fs contamination in open dumping sites of Asian developing countries. On the basis of the result of this study, we have addressed a new environmental issue that open dumping sites are potential sources of PCDD/Fs and related compounds, and dioxin contamination in dumping sites may become a key environmental problem in developing countries. 相似文献
47.
Vaidyanathan Subramanian K. Eswara Prasada Rao Melak H. Mengesha Ramamurthi Jambunathan 《Journal of the science of food and agriculture》1987,39(4):289-295
Seventy sorghum cultivars from the world germplasm collection maintained at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) were screened for total sugar content of the stalks. The total sugar content in stalks harvested after physiological maturity ranged from 17.8 to 40.3% on dry weight basis. The total sugar content in grains of 15 selected cultivars ranged from 1.02 to 2.23%. Nine cultivars having more than 34% total sugar content in stalks showed consistency for sugar content when grown for two seasons. Juiciness of stalks from five cultivars as estimated by the quantity of juice extracted varied from 266 to 464 ml per kilogram of fresh stalks. The total sugar content in the juice of five cultivars varied from 7.0 to 15.9%. 相似文献
48.
Sequential separation of lanthanides, thorium and uranium using novel solid phase extraction method from high acidic nuclear wastes 总被引:1,自引:0,他引:1
A novel grafted polymer for selective extraction and sequential separation of lanthanides, thorium and uranium from high acidic wastes has been developed by grafting Merrifield chloromethylated (MCM) resin with octyl(phenyl)-N,N-diisobutylcarbamoyl-methylphosphine oxide (CMPO) (MCM-CMPO). The grafting process is well characterized using FT-IR spectroscopy, (31)P and (13)C CPMAS (cross-polarized magic angle spin) NMR spectroscopy and CHNPS elemental analysis. The influence of various physico-chemical parameters during metal ion extraction by the resin phase are studied and optimized by both static and dynamic methods. The resin shows very high sorption capacity values of 0.960mmolg(-1) for U(VI), 0.984mmolg(-1) for Th(IV), 0.488mmolg(-1) for La(III) and 0.502mmolg(-1) for Nd(III) under optimum HNO(3) medium, respectively. The grafted polymer shows faster rate exchange kinetics (<5min is sufficient for 50% extraction) and greater preconcentration ability, with reusability exceeding 20 cycles. During desorption process, sequential separation of the analytes is possible with varying eluting agents. The developed grafted resin has been successfully applied in extracting Th(IV) from high matrix monazite sand, U(VI) and Th(IV) from simulated nuclear spent fuel mixtures. All the analytical data is based on triplicate analysis and measurements are within 3.5% rsd reflecting the reproducibility and reliability of the developed method. 相似文献
49.
S Prasad S Mitra E Subramanian D Velmurugan RB Rao P Balaram 《Canadian Metallurgical Quarterly》1994,198(2):424-430
The crystal structure of the tripeptide Boc-Leu-Dpg-Val-OMe (Dpg, alpha, alpha -di-n-propylglycine) reveals the coexistence of two distinct backbone conformations. In molecule A the Dpg residue adopts a fully extended conformation (phi = 76.0 degrees, psi = 180.0 degrees) while in molecule B a left handed helical conformation (phi = 62.8 degrees, psi = 39.6 degrees) is observed. Molecule B adopts a folded structure corresponding to a highly distorted Type II beta-turn conformation, which lacks an intramolecular 4 -> 1 hydrogen bond. In contrast, molecule A has an open, extended conformation. The results demonstrate that both fully extended and helical conformations are energetically accessible to the Dpg residue. 相似文献
50.
Electrochemical cell current requirements for toxic organic waste destruction in Ce(IV)-mediated electrochemical oxidation process 总被引:1,自引:0,他引:1
Vasily V. Kokovkin Sang Joon Chung Subramanian Balaji Manickam Matheswaran Il-Shik Moon 《Korean Journal of Chemical Engineering》2007,24(5):749-756
The electrochemical cell for cerium oxidation and reactor for organic destruction are the most important operation units for
the successful working mediated electrochemical oxidation (MEO) process. In this study, electrochemical cells with DSA electrodes
of two types, single stack and double stack connected in series, were used. The performances towards the electrochemical generation
of Ce(IV) in nitric acid media at 80 °C were studied. The current-voltage curves and cerium electrolysis kinetics showed the
dependence on number of cell stacks needed to be connected in series for the destruction of a given quantity of organic pollutant.
The presence of an optimum region for Ce(III) oxidation with a contribution of oxygen evolution, especially at low Ce(III)
concentration (high conversion ratios), was found. The cells were applied for the Ce(IV) regeneration during the organic destruction.
The cell and reactor processes were fitted in a simple model proposed and used to calculate the current needed in terms of
Ce(III) oxidation rate and the number of cell stacks required for maintaining Ce(IV)/Ce(III) ratio at the same level during
the organic destruction. This consideration was based on the kinetic model previously developed by us for the organic destruction
in the MEO process. 相似文献