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排序方式: 共有1495条查询结果,搜索用时 11 毫秒
1.
An alternating digital tree (ADT) algorithm for 3D geometric searching and intersection problems 总被引:4,自引:0,他引:4
Javier Bonet Jaime Peraire 《International journal for numerical methods in engineering》1991,31(1):1-17
A searching algorithm is presented for determining which members of a set of n points in an N dimensional space lie inside a prescribed space subregion. The algorithm is then extended to handle finite size objects as well as points. In this form it is capable of solving problems such as that of finding the objects from a given set which intersect with a prescribed object. The suitability of the algorithm is demonstrated for the problem of three dimensional unstructured mesh generation using the advancing front method. 相似文献
2.
The new emerging area of Enterprise Wide Optimization (EWO) has focused the attention in effectively solving the combined production/distribution scheduling problem. The importance of logistic activities performed in multi-site environments comes from the relative magnitude of the associated transportation costs and the good chance of getting large savings on such expenses. This paper first develops an exact MILP mathematical formulation for the multiple vehicle time-window-constrained pickup and delivery (MVPDPTW) problem. The approach is able to account for many-to-many transportation requests, pure pickup and delivery tasks, heterogeneous vehicles and multiple depots. Optimal solutions for a variety of benchmark problems with cluster/random distributions of pickup and delivery locations and limited sizes in terms of customer requests and vehicles have been discovered. However, the computational cost exponentially grows with the number of requests. For large-scale m-PDPTW problems, a local search improvement algorithm steadily providing a better solution through two evolutionary steps is also presented. A neighborhood structure around the starting solution is generated by first allowing multiple request exchanges among nearby trips and then permitting the reordering of nodes on every individual route. If a better set of routes is found, both steps are repeated until no improved solution is discovered. Compact MILP mathematical formulations for both sub-problems have been developed and solved through an efficient branch-and-bound algorithm. A significant number of large-scale m-PDPTW benchmark problems, some of them including up to 100 transportation requests, were successfully solved in reasonable CPU times. 相似文献
3.
Claudio Garibay‐Orijel Elvira Ríos‐Leal Jaime García‐Mena Hctor Mario Poggi‐Varaldo 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(10):1180-1187
A fluidized bed bioreactor (FBBR) was operated for more than 575 days to remove 2,4,6‐trichlorophenol (TCP) and phenol (Phe) from a synthetic toxic wastewater containing 80 mg L?1 of TCP and 20 mg L?1 of Phe under two regimes: Methanogenic (M) and Partially‐Aerated Methanogenic (PAM). The mesophilic, laboratory‐scale FBBR consisted of a glass column (3 L capacity) loaded with 1 L of 1 mm diameter granular activated carbon colonized by an anaerobic consortium. Sucrose (1 g COD L?1) was used as co‐substrate in the two conditions. The hydraulic residence time was kept constant at 1 day. Both conditions showed similar TCP and Phe removal (99.9 + %); nevertheless, in the Methanogenic regime, the accumulation of 4‐chlorophenol (4CP) up to 16 mg L?1 and phenol up to 4 mg L?1 was observed, whereas in PAM conditions 4CP and other intermediates were not detected. The specific methanogenic activity of biomass decreased from 1.01 ± 0.14 in M conditions to 0.19 ± 0.06 mmolCH4 h?1 gTKN?1 in PAM conditions whereas the specific oxygen uptake rate increased from 0.039 ± 0.008 in M conditions to 0.054 ± 0.012 mmolO2 h?1 gTKN?1, which suggested the co‐existence of both methanogenic archaea and aerobic bacteria in the undefined consortium. The advantage of the PAM condition over the M regime is that it provides for the thorough removal of less‐substituted chlorophenols produced by the reductive dehalogenation of TCP rather than the removal of the parent compound itself. Copyright © 2005 Society of Chemical Industry 相似文献
4.
HE Vi?tor F Klumper RJ Meerman A Brand HH Kanhai 《Canadian Metallurgical Quarterly》1998,18(4):325-331
Histamine is an important mediator in allergic reactions, gastric acid secretions, and neurotransmission in the central nervous system. Basophils and mast cells are the main sources of histamine, which is formed from L-histidine by histidine decarboxylase (HDC). However, the regulatory mechanism of HDC in these cells remains unclear. We examined the regulation of HDC activity and gene expression using a unique human mast cell line, HMC-1, after stimulation with phorbol 12-myristate 13-acetate (PMA) or ionomycin. HDC activity was increased from 52.1+/-0.4 (mean+/-standard deviation) to 154+/-6.9, or 105.6+/-6.2 pmol/min/mg protein (n = 3), 4 hours after stimulation with PMA (10 ng/mL) or ionomycin (10[-6] M). Although actinomycin D had no effect on this increase, cycloheximide completely inhibited the increase caused by these stimuli. The population of HMC-1 cells containing HDC protein was increased after stimulation with either PMA or ionomycin as evaluated by immunocytochemical analysis with anti-HDC antibody as a marker. HMC-1 constitutively expressed HDC mRNA, and its level was not increased with these stimuli. These results suggest that the increase of HDC activity in HMC-1 induced by PMA or ionomycin is regulated at the translational level. 相似文献
5.
In this research, the effect of dielectric barrier discharge on mechanically manufactured (sawn, planed or polished) wood surfaces is investigated. The experiments have shown that the best hydrophilia is obtained with a cold plasma discharge in air under atmospheric pressure. Other gases such as helium, nitrogen, and argon have been tested, too. Changes of the wood surface properties were determined by absorption of water and contact angle measurements. As a result of a 1 to 20 seconds long exposure to plasma, wood surfaces became hydrophilic. The absorption of water in wood can be changed up to 22 times higher after plasma treatment in air for 20 seconds duration. The fracture strength of glued wood has been increased by 68% after this plasma pretreatment. Using plasma treatment in methane or acetylene wood surfaces are changed to hydrophobic properties. After plasma treatment for 1 min. in a Ar:CH4=80:20 gas mixture under atmospheric pressure, the absorption of water in wood is 32 times lower than without plasma treatment. As mentioned before, plasma treatment can produce hydrophobic and hydrophilic wood surfaces. But a good homogeneity of the gas discharge is necessary for the plasma treatment of wood. Zusammenfassung Im Rahmen dieser Arbeit werden die Auswirkungen der dielektrisch behinderten Entladung bei Atmosphärendruck auf mechanisch bearbeitete Holzoberflächen (gesägt, gehobelt oder geschliffen) untersucht. Die Experimente haben gezeigt, dass die höchste Hydrophilität bei einem in Luftatmosphäre gezündetem Plasma erreicht wird. Es werden auch andere Gase verwendet, wie z.B. Helium, Stickstoff und Argon. Zur Untersuchung der veränderten mechanischen und energetischen Eigenschaften der Holzoberflächen werden der Tropfen-Versuch und die Kontaktwinkelmessung verwendet. Durch eine 1 bis 20 Sekunden lange Plasmabehandlung können die Oberflächen hydrophil gestaltet werden. So kann die Eindringzeit von Wasser um Faktor 22 gesteigert werden durch eine 20 Sekunden lange Plasmabehandlung in Umgebungsluft. Die Bruchfestigkeit von Leimholz wird durch die gleiche Plasmavorbehandlung um 68% gesteigert. Werden als Plasmabehandlungsgas Methan oder Acetylen eingesetzt, so wird die Holzoberfläche hydrophob. Durch eine 60 Sekunden lange Plasmabehandlung in einem Ar:CH4=80:20 Gasgemisch bei Atmosphärendruck wird die Eindringszeit von Wasser um den Faktor 32 gesenkt. Mit Hilfe der Plasmabehandlung können also sowohl hydrophobe als auch hydrophile Holzoberflächen erzeugt werden. Jedoch wird für die Plasmabehandlung von Holz eine sehr homogene Gasentladung benötigt. 相似文献
6.
7.
This paper mainly focuses on the influence of three kinds of media: air, air-10%PA (Nylon) and air-10% POM (polyoxymethylene) on low-voltage circuit breaker arcs. A threedimensional (3-D) model of arc motioa under the effect of external magnetic field is built based on magnetohydrodynamics (MHD) equations. By adopting the commercial computational fluid dynamics (CFD) package based on the control-volume method, the above MHD equations are solved. For the media of air-10%PA and air-10%POM, the distributions of stationary temperature and electrical potential and the transient motion processes are compared with those of air arc. The research shows that both air-10%PA and air -10% POM can cool the arc plasma and the former is more effective. Both of them can increase the stationary voltage as well. Moreover, the presence of the two mixtures can accelerate the arc motion toward the quenching area and ensures the arc quenched in time. 相似文献
8.
Jaime Ortiz Óscar Palma Natalia González Santiago P. Aubourg 《European Journal of Lipid Science and Technology》2008,110(12):1127-1135
The flow ice system including ozone (OFI condition) was tested for slaughtering and storage (up to 16 days) of farmed rainbow trout (Oncorhynchus mykiss). Lipid damage analyses were carried out and compared to sensory acceptance and instrumental colour changes. Comparison to individuals processed with the flow ice system in the absence of ozone (FI condition) was undertaken. Rainbow trout slaughtered and chilled under FI and OFI conditions showed a low lipid damage development, according to lipid oxidation and hydrolysis events and lipid composition (polyunsaturated fatty acids, phospholipids and endogenous antioxidants) changes. Additionally, both icing conditions led to largely good quality and shelf life times and to the absence of changes in colour properties. It is concluded that flow ice as such, or including the presence of ozone, can be considered as ideal strategy to be employed as slaughtering and storage system during the commercialisation of the actual farmed species. The ozone presence has shown some profitable effects as leading to an extended shelf life time by quality retention of several sensory parameters; in contrast, some negligible negative effects could be observed on the secondary and tertiary lipid oxidation development. However, the oxidation values reached by individuals kept under OFI conditions cannot be considered as particularly high. 相似文献
9.
Jos O. Valderrama Jaime M. Martí nez Estrella R. Asp e Marlene D. Roeckel 《Chemical Engineering Communications》1986,44(1):331-346
An experimental study on mixing, degree of suspension and power consumption in solid-liquid suspensions was done. A system similar to those found in anaerobic fermentation processes of animal manures was used, and an existing mixing equipment was adapted for the study. Power consumption and degree of suspension for both mechanical mixing and mixing by gas was determined. The influence of variables such as geometry, solids concentration, stirrer velocity, and gas velocity was studied, discussed, and compared to data from the literature. Best results were obtained for gas mixing, the power consumption being about one fourth of that required by mechanical agitation. Finally, extended correlations relating Power and Reynolds numbers for mechanical mixing and mixing by gas are proposed. 相似文献
10.
In this work a simple method to solve the forward displacement analysis of the general 6-6 fully parallel manipulator is applied. The method is based on generating closure equations upon the unknown coordinates of three points embedded to the moving platform. The method is easy to follow and it is available for both, planar and three-dimensional moving platforms. Numerical examples are included with the purpose to show the application of the method. 相似文献