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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.
The thermal evolution of defects produced by ion irradiation is studied by kinetic Monte Carlo and Rate Theory approaches. An isochronal annealing is simulated to evidence the different thermally activated mechanisms that govern defect evolution. KMC simulations show that in the case of ion irradiation, additional recovery peaks should be expected, in comparison to electron irradiation conditions. A comparison between kMC and RT results indicates that some of these peaks are due to spatially – correlated recombinations that occur at low temperature. Therefore kMC and RT approaches differ at low temperature. However, at higher temperature results obtained by both models are in near perfect agreement. In addition, we studied the influence of vacancy cluster mobility on the evolution of damage. KMC simulations show that the mobility of V2, V3 and V4 clusters does not significantly affect the evolution of defects and can be neglected in these conditions. 相似文献
4.
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
5.
A population from a Central Spanish region (Tormes-Alberche Valley) has been investigated for the presence of red-green colour vision defects. A sample of 998 subjects (469 male and 529 female) was analyzed. To identify colour vision defects, Ishihara test plates were used. The red-green colour blindness percentage obtained was 4.69 +/- 0.976% for males (2.13% protan and 2.56% deutan types) and none of the females tested were found to be colour blind. These results are within the variation range of Mediterranean populations and lower than the usual frequencies among non-Mediterranean European samples. 相似文献
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8.
This essay describes the domain of research in communication law and policy. It is based on a content analysis of research published in the journal Communication Law and Policy (1996–2004), papers presented to the Communication Law and Policy Division at annual conferences of the International Communication Association (1997–2004), as well as consideration of other resources. The most frequent areas for research were media regulation, Internet policy, and freedom of expression issues. After reviewing recent literature on the first two topics, we identified and showcased two emergent categories deserving future attention: communication and the law (particularly fair trial-free press issues) and implications of the burgeoning consolidation of media ownership. 相似文献
9.
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
10.
A Fernandez Rodríguez M Arrabal Martín JF Domínguez Molinero JL Mijan Ortiz J Sánchez Tamayo A Zuluaga Gómez 《Canadian Metallurgical Quarterly》1995,19(8):620-626
A prospective study was conducted on 374 patients with urinary lithiasis, aiming to analyze the participation of oxalate in the lithogenesis and composition of the calcium oxalate calculi, alone or associated to other factors. METHODOLOGY: Metabolic urinary study of the patient and analysis of calculi with infrared spectrography and optical microscopy. RESULTS: 26.3% patients had hyperoxaluria and 77.5% of the calculi contain calcium oxalate; these are 167 cases of calcium oxalate, 110 of oxalate and calcium phosphate and 13 cases of mixed calcium oxalate and uric acid lithiasis. 43.4% patients with pure monohydrate calcium oxalate calculi have hypercalciuria, 22.6% hyperoxaluria and 19% hyperuricosuria. Dihydrated calcium oxalate calculi are related to high hypercalciuria in 65% cases and to significant hyperoxaluria in 35% cases. 45% patients present a single lithogenic factor, either hypercalciuria (49.6%), hyperoxaluria (20.6%), hyperuricosuria (13.74%), hypocitraturia (9%), urinary infection (1.5%), A.T.R. (2.25%) or acid oliguria (3%). 相似文献