131,948 research outputs found
Simulazione del ciclo di lavoro di un martello demolitore
No full textQuesto studio tratta la
simulazione numerica del ciclo
di lavoro di una macchina
oleoidraulica a percussione:
il martello demolitore.
Il comportamento dinamico
delle masse mobili interne
alla macchina viene
presentato sulla base di
un modello parametrico
appositamente allestito
al fi ne di simulare i fenomeni
fi sici che governano il
funzionamento della macchina
stessa. Senza ricorrere a
misure invasive, i rilievi
sperimentali di pressione e
portata in ingresso al martello
consentono una apprezzabile
validazione del modello
di simulazione
Where are kin recognition cues in the face? Annual Meeting of the Vision Sciences Society
No full textObservers accurately judge children's degree of kinship given facial photographs (Dal Martello & Maloney, VSS2002). We report two experiments intended to determine where in the face the cues signalling kinship fall. Since the upper face changes less than the lower during development (Enlow & Hans, 1996), we hypothesized that observers would rely on age-invariant features in the upper face. Stimuli:30 pairs of photographs, each photograph portraying a child's face with background removed. Half were of siblings, half, unrelated. The children's ages spanned 14 years. Observers: 220 observers judged each pair as siblings or not. We summarized performance in each condition by signal detection d' estimates. Experiment 1 Conditions: Full Face visible (FF); Upper Half face visible (UH); Lower Half face visible (LH). Different observers participated in each condition. Results: Performance in FF (d' = 1.19) and in UH condition (d''=1.12) did not differ significantly (p = n.s.). Performance in LH (d' = 0.41) was significantly lower (p < 0.0001) than that in other conditions.
Experiment 2 Conditions: Full Face visible (FF); face visible except for a small mask over the eye region (ME); face visible except for the masked mouth (MM). Results: Performance in the masked conditions (ME d' = 0.82; MM d' = 1.11) was not significantly different from that found in FF (d' = 1.02).
Conclusion: Observers (correctly) use kinship cues in the upper half face but, surprisingly, the eye region either provides little information or cues available in that region are redundant with other facial cues
Kin recognition based on viewing photographs of children's faces is not affected by facial inversion.
No full textBackground: Many facial tasks such as identity recognition and judgments of emotion are more difficult when faces are inverted. We report an objective task (judgment of kinship of pairs of children) where task performance does not deteriorate with inversion of stimuli. Methods: 30 pairs of color photographs, each photograph portraying a frontal view of a child's face with background removed. Half of the pairs were siblings, half unrelated. The children's ages spanned 14 years. The distribution of age differences for related and unrelated pairs was matched as were gender differences. A total of 118 adult observers judged each pair as siblings or not. We summarized performance in each condition by signal detection d′ estimates. Conditions: Upright face (UF); face flipped around a horizontal axis (IF); 180° rotated face (RF). Different observers participated in each condition. Results: Performance in the UF condition (d′ = 1.058), IF condition (d′ =1.197), and RF condition (d′ = 1.048) were not significantly different (p > 0.05). Likelihood criterion (β) values of UF (β = 0.967), IF (β = 1.054), RF (β = 1.033) also did not differ significantly (p > 0.05). The β values of UF, IF and RF were not significantly different from 1 (p > 0.05): there was no significant bias in classifying children as related or unrelated. Conclusion: Allocentric kin recognition is not disrupted by inversion of the facial stimuli: the judgment appears to rely on inversion invariant cues. We discuss this result in conjunction with previous work (Dal Martello & Maloney, 2006; DeBruine et al., 2009) concerning localization of kin recognition cues in the face
Exact solution of the two-dimensional finite bin packing problem
No full textGiven a set of rectangular pieces to be cut from an unlimited number of standardized stock pieces (bins), the Two-Dimensional Finite Bin Packing Problem is to determine the minimum number of stock pieces that provide all the pieces. The problem is NP-hard in the strong sense and finds many practical applications in the cutting and packing area. We analyze a well-known lower bound and determine its worst-case performance. We propose new lower bounds which are used within a branch-and-bound algorithm for the exact solution of the problem. Extensive computational testing on problem instances from the literature involving up to 120 pieces shows the effectiveness of the proposed approach
The Search for the sidereal and solar diurnal modulations in the total MACRO muon data set.
No full textHigh-energy cosmic ray physics with the MACRO detector at Gran Sasso: Part 1. Analysis methods and experimental results.
No full textThree-dimensional bin packing problem
No full textThe problem addressed in this paper is that of orthogonally packing a given set of rectangular-shaped items into the minimum number of three-dimensional rectangular bins. The problem is strongly NP-hard and extremely difficult to solve in practice. Lower bounds are discussed, and it is proved that the asymptotic worst-case performance ratio of the continuous lower bound is 1/8. An exact algorithm for filling a single bin is developed, leading to the definition of an exact branch-and-bound algorithm for the three-dimensional bin packing problem, which also incorporates original approximation algorithms. Extensive computational results, involving instances with up to 90 items, are presented: It is shown that many instances can be solved to optimality within a reasonable time limit
Minimizing the Sumof Weighted Completion Times with Unrestricted Weights.
No full textGiven a set of tasks with associated processing times, deadlinesand weights unrestricted in sign,we consider the problem of determining a task schedule on one machineby minimizing the sum of weighted completion times.The problem is NP-hard in the strong sense.We present a lower bound based on task splitting,an approximation algorithm, and two exact approaches, one basedon branch-and-bound and one on dynamic programming. An overall exact algorithmis obtained by combining these two approaches. Extensive computationalexperiments show the effectiveness of the proposed algorithms
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