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排序方式: 共有523条查询结果,搜索用时 15 毫秒
1.
R Albrecht TC Awes C Baktash P Beckmann F Berger R Bock G Claesson G Clewing L Dragon A Eklund RL Ferguson A Franz S Garpman R Glasow HA Gustafsson HH Gutbrod J Idh P Jacobs K Kampert BW Kolb P Kristiansson IY Lee H Loehner I Lund FE Obenshain A Oskarsson I Otterlund T Peitzmann S Persson F Plasil AM Poskanzer M Purschke H Ritter S Saini R Santo HR Schmidt T Siemiarczuk SP Sorensen E Stenlund ML Tincknell GR Young 《Canadian Metallurgical Quarterly》1991,44(6):2736-2752
2.
Current desktop computers typically use fan-heat sinks for cooling the CPU, referred to as active heat sinks. This work seeks to determine the heat rejection limits for such fan-heat sinks, within specific fan and heat sink space limits. A fixed volume, 80 /spl times/ 60 /spl times/ 50 mm is chosen as the limiting dimensions, which includes the fan volume. The present work addresses plane fin heat sinks, on which a typical 60 mm fan is mounted. Both duct flow and impinging flow are considered. Analytically based models are used to predict the optimum geometry (minimum convection resistance) for plane fins with duct and impinging flow configurations. Also assessed are the effects of increased fan speed (up to 25%) and heat sink base size (33% increase) on air-cooling limits in duct and impinging flow. Tests on fan-heat sinks are done to validate the predictions. Optimization is also done for an enhanced (offset-strip) fin geometry in duct flow. The plane fin is found to outperform the enhanced geometry. 相似文献
3.
In this paper, we have proposed some new numerical and semi-analytical methods for developing an equivalent three-layer model of an MQW waveguide. The waveguiding properties like effective index, field distribution, and fractional power within the core of the waveguide of these equivalent structures are compared with those of previously reported equivalent methods. These results are also compared with the results obtained from the exact multilayer analysis of the MQW waveguide. The waveguiding properties are accurately predicted by the semi-analytical method using variational analysis, and the computational effort is significantly reduced. The use of the three-layer equivalent is illustrated in obtaining an estimation of the waveguide losses and is used to study the effect of nonlinearity 相似文献
4.
The thermodynamic properties of polymer solutions are frequently described in terms of the Flory-Huggins equation. This equation includes a parameter χ, which depends upon the intermolecular forces acting between the molecules in a solution. The experimental determination of χ was performed by an improved microtechnique and extended to a wide range of polar and nonpolar diluents of polyethylene. Careful correlations are prescribed for calculating χ from pure-component properties; they are based on an extension of the Hildebrand-Scatchard theory of solutions and on the theory of intermolecular forces. Polar (τ) and nonpolar (δ) solubility parameters are presented for a variety of solvents. For polyethylene—nonpolar solvent systems we have emphasized the factor deciding the sign of heat of mixing, while for polyethylene-polar solvent systems we have determined the contribution of dipole-induced dipole interactions ψ (δτ) in interchange-energy density B and, hence, χ. 相似文献
5.
Juneja Mamta Saini Sumindar Kaur Gupta Jatin Garg Poojita Thakur Niharika Sharma Aviral Mehta Manan Jindal Prashant 《Multimedia Tools and Applications》2021,80(19):29199-29249
Multimedia Tools and Applications - Prostate cancer (PCa) has become the second most dreadful cancer in men after lung cancer. Traditional approaches used for treatment of PCa were manual, time... 相似文献
6.
Harsh Bhasin Gitanshu Behal Nimish Aggarwal Raj Kumar Saini Shivani Choudhary 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2016,20(9):3403-3410
Diploid genetic algorithms (DGAs) promise robustness as against simple genetic algorithms which only work towards optimization. Moreover, these algorithms outperform others in dynamic environments. The work examines the theoretical aspect of the concept by examining the existing literature. The present work takes the example of dynamic TSP to compare greedy approach, genetic algorithms and DGAs. The work also implements a greedy genetic approach for the problem. In the experiments carried out, the three variants of dominance were implemented and 115 runs proved the point that none of them outperforms the other. 相似文献
7.
This paper presents an application of a hybrid fuzzy multi-objective evolutionary algorithm (HFMOEA) for solving a highly constraint, mixed integer type, complex multi-objective reactive power market clearing (RPMC) problem for the competitive electricity market environment. In HFMOEA based multi-objective optimization approach, based on the output of a fuzzy logic controller crossover and mutation probabilities are varied dynamically. It enhances stochastic search capabilities of HFMOEA. In multi-objective RPMC optimization framework, two objective functions namely the total payment function (TPF) for reactive power support from generators and synchronous condensers and the total real transmission loss (TRTL) are minimized simultaneously for clearing the reactive power market. The proposed HFMOEA based multi-objective RPMC scheme is tested on a standard IEEE 24 bus reliability test system and its performance is compared with five other multi-objective evolutionary techniques such as MOPBIL, NSGA-II, UPS-EMOA and SPEA-2 and a new extended form of NSGA (ENSGA-II). Applying all these six evolutionary techniques, a detailed statistical analysis using T-test and boxplots is carried out on three performance metrics (spacing, spread and hypervolume) data for RPMC problem. The obtained simulation results confirm the overall superiority of HFMOEA to generate better Pareto-optimal solutions with higher convergence rate as compared to above mentioned algorithms. Further, TPF and TRTL values corresponding to the best compromise solutions are obtained using said multi-objective evolutionary techniques. These values are compared with one another to take better market clearing decisions in competitive electricity environment. 相似文献
8.
9.
Radio Frequency Identification (RFID) based systems have been used in different applications in the Architecture, Engineering, Construction, Owner and Operator (AECOO) industry. Applications are mainly designed for specific lifecycle stage of the facility and serve the needs of only one of the stakeholders. This would increase the cost and the labor for adding and removing tags and eliminate the chance of using shared resources. In this paper, the usage of tags permanently attached to components is proposed where the memory of the tags is used during the lifecycle by different stakeholders for data storage and handover. A Building Information Model (BIM) database is used for tackling the interoperability issues allowing different users to access and share the data. To securely and efficiently store data on RFID tags in ifcXML format, multi-level encryption together with role-based access control is applied on the data stored on RFID tags. Each user is assigned a certain role and can only access the part of data for which he has authorization according to a predefined role and the Access Control Policy. To explore the technical feasibility of the proposed approach, a case study considering both facilities management and emergency management has been implemented and tested at Concordia University. 相似文献
10.
M. Fratini G. Campi L. Simonelli V. Palmisano S. Agrestini M. Filippi N. L. Saini A. Bianconi 《Journal of Superconductivity and Novel Magnetism》2005,18(5-6):671-674
The interstitial oxygen ordering in a La2CuO4+ y (y = 0.08) single crystal with a T c = 38 K has been investigated. We have studied the growth dynamics of the three dimensional (3D) ordered phase, called Q2, at different temperatures under X-ray illumination. The critical temperature T 0~334 K of the order-disorder transition for the Q2 phase has been determined. We have found that the illumination of the sample with a continuous polarized synchrotron radiation X-ray flux stimulates the oxygen ordering kinetics. The photoinduced ordering process shows a threshold characteristic of cooperative phenomena and its kinetics shows a temperature dependence that is controlled by the activation energy E A = 100 meV. 相似文献