Gotowa bibliografia na temat „Effet intermodal”

In this paper, we study the nonclassical properties and find out the effect of photon addition on these properties as well as the process of teleportation in the two-mode photon-added displaced squeezed (TMPADS) states. We derive the analytic expressions of the Wigner function, the photon number distribution and the intermode photon antibunching for these states. We show that photon addition operation not only makes the Wigner function become negative but also leads to increase the degree of antibunching. The peak of the photon number distribution becomes flatter and shifts to the greater number of photons by adding photons to both modes simultaneously. Furthermore, it is proved that the degree of intermodal entanglement becomes bigger and bigger through increasing the number of photons added to both modes. As expected, when using these states as an entanglement resource to teleport a state, the average fidelity of teleportation process is also improved by increasing the number of added photons.

Abstract Transparency in transport processes is becoming increasingly important for transport companies to improve internal processes and to be able to compete for customers. One important element to increase transparency is reliable, up-to-date and accurate arrival time prediction, commonly referred to as estimated time of arrival (ETA). ETAs are not easy to determine, especially for intermodal freight transports, in which freight is transported in an intermodal container, using multiple modes of transportation. This computational study describes the structure of an ETA prediction model for intermodal freight transport networks (IFTN), in which schedule-based and non-schedule-based transports are combined, based on machine learning (ML). For each leg of the intermodal freight transport, an individual ML prediction model is developed and trained using the corresponding historical transport data and external data. The research presented in this study shows that the ML approach produces reliable ETA predictions for intermodal freight transport. These predictions comprise processing times at logistics nodes such as inland terminals and transport times on road and rail. Consequently, the outcome of this research allows decision makers to proactively communicate disruption effects to actors along the intermodal transportation chain. These actors can then initiate measures to counteract potential critical delays at subsequent stages of transport. This approach leads to increased process efficiency for all actors in the realization of complex transport operations and thus has a positive effect on the resilience and profitability of IFTNs.

When attention is directed to stimuli in a given modality and location, information processing in other irrelevant modalities at this location is affected too. This spread of attention to irrelevant stimuli is often interpreted as superiority of location selection over modality selection. However, this conclusion is based on experimental paradigms in which spatial attention was transient whereas intermodal attention was sustained. Furthermore, whether modality selection affects processing in the task-relevant modality at irrelevant locations remains an open question. Here, we addressed effects of simultaneous spatial and intermodal attention in an EEG study using a balanced design where spatial attention was transient and intermodal attention sustained or vice versa. Effects of spatial attention were not affected by which modality was attended and effects of intermodal attention were not affected by whether the stimuli were at the attended location or not. This suggests not only spread of spatial attention to task-irrelevant modalities but also spread of intermodal attention to task-irrelevant locations. Whether spatial attention was transient or sustained did not alter the effect of spatial attention on visual N1 and Nd1 responses. Prestimulus preparatory occipital alpha band responses were affected by both transient and sustained spatial cueing, whereas late post-stimulus responses were more strongly affected by sustained than by transient spatial attention. Sustained but not transient intermodal attention affected late responses (>200 msec) to visual stimuli. Together, the results undermine the universal superiority of spatial attention and suggest that the mode of attention manipulation is an important factor determining attention effects.

Rail–truck intermodal terminals are an important type of dry port and play a vital role in inland freight transport. This paper addresses the container loading problem in rail–truck intermodal terminals considering energy consumption under the sustainability concept. We analyze the effect factors of energy efficiency for container loading operations and develop an optimization model to minimize the total handling time and container reshuffling. A genetic algorithm is designed to obtain the optimal container loading sequence. Computational experiments on a specific Chinese rail–truck intermodal terminal were conducted to evaluate the performance of our approach. Results show our approach has a good performance for different sizes, and the total handing time, reshuffling times and energy consumption of the handling task are prominently decreased.

Numerous studies have demonstrated effects of spatial attention within single sensory modalities (within-modal spatial attention) and the effect of directing attention to one sense compared with the other senses (intermodal attention) on cortical neuronal activity. Furthermore, recent studies have been revealing that the effects of spatial attention directed to a certain location in a certain sense spread to the other senses at the same location in space (cross-modal spatial attention). The present study used magnetoencephalography to examine the temporal dynamics of the effects of within-modal and cross-modal spatial and intermodal attention on cortical processes responsive to visual stimuli. Visual or tactile stimuli were randomly presented on the left or right side at a random interstimulus interval and subjects directed attention to the left or right when vision or touch was a task-relevant modality. Sensor-space analysis showed that a response around the occipitotemporal region at around 150 ms after visual stimulation was significantly enhanced by within-modal, cross-modal spatial, and intermodal attention. A later response over the right frontal region at around 200 ms was enhanced by within-modal spatial and intermodal attention, but not by cross-modal spatial attention. These effects were estimated to originate from the occipitotemporal and lateral frontal areas, respectively. Thus the results suggest different spatiotemporal dynamics of neural representations of cross-modal attention and intermodal or within-modal attention.

Abstract Uncertainty in tropical rainfall projections under increasing radiative forcing is studied by using 26 models from phase 5 of the Coupled Model Intercomparison Project. Intermodel spread in projected rainfall change generally increases with interactive sea surface temperature (SST) warming in coupled models compared to atmospheric models with a common pattern of prescribed SST increase. Moisture budget analyses reveal that much of the model uncertainty in tropical rainfall projections originates from intermodel discrepancies in the dynamical contribution due to atmospheric circulation change. Intermodel singular value decomposition (SVD) analyses further show a tight coupling between the intermodel variations in SST warming pattern and circulation change in the tropics. In the zonal mean, the first SVD mode features an anomalous interhemispheric Hadley circulation, while the second mode displays an SST peak near the equator. The asymmetric mode is accompanied by a coupled pattern of wind–evaporation–SST feedback in the tropics and is further tied to interhemispheric asymmetric change in extratropical shortwave radiative flux at the top of the atmosphere. Intermodel variability in the tropical circulation change exerts a strong control on the spread in tropical cloud cover change and cloud radiative effects among models. The results indicate that understanding the coupling between the anthropogenic changes in SST pattern and atmospheric circulation holds the key to reducing uncertainties in projections of future changes in tropical rainfall and clouds.

Abstract This study investigates how intermodel differences in large-scale ocean dynamics affect the tropical Pacific sea surface temperature (SST) warming (TPSW) pattern under global warming, as projected by 32 models from phase 5 of the Coupled Model Intercomparison Project (CMIP5). The largest cause of intermodel TPSW differences is related to the cloud–radiation feedback. After removing the effect of cloud–radiation feedback, the authors find that differences in ocean advection play the next largest role, explaining around 14% of the total intermodel variance in TPSW. Of particular importance are differences in climatological zonal overturning circulation among the models. With the robust enhancement of ocean stratification across models, models with relatively strong climatological upwelling tend to have relatively weak SST warming in the eastern Pacific. Meanwhile, the pronounced intermodel differences in ocean overturning changes contribute little to uncertainty in the TPSW pattern. The intermodel differences in climatological zonal overturning are found to be associated with the intermodel spread in climatological SST. In most CMIP5 models, there is a common cold tongue associated with an overly strong overturning in the climatology simulation, implying a La Niña–like bias in the TPSW pattern projected by the MME of the CMIP5 models. This provides further evidence for the projection that the TPSW pattern should be closer to an El Niño–like pattern than the MME projection.

This paper discusses the most attractive emission compliance options (emission abatement technologies and cleaner fuels) in intermodal transport chains that include short sea shipping. Most studies on emissions-based transport chain comparisons have estimated high levels of nitrogen and sulfur oxide emissions in maritime transportation, decreasing its competitiveness. However, the consequences of regulatory and technological developments and the integration of maritime transport in intermodal transport chains have not yet been considered in detail. In order to address this research gap, a numerical model for computing emissions from different transport modes in an intermodal transport network, under the effect of these developments, is presented that is based on bottom–up emission factors that depend on the fuel type, engine type, and operational profile of each vehicle. Different emissions scenarios are chosen for specific unimodal and intermodal routes (short sea shipping-based) between Portugal and northwestern Europe. Conclusions are drawn on estimated values of air pollutant emissions and greenhouse emissions, in CO2-eq per unit of cargo, in each scenario. These results allow the identification of the most environmentally friendly transport chains, thus supporting the development of adequate transport policies.

Understanding the spatially varying effect mechanism of intermodal connection on metro ridership helps policymakers develop differentiated interventions to promote metro usage, especially for megacities with multiple city sub-centers and ring roads. Using multiple datasets in Shanghai, this study combines Light Gradient Boosting Machine (LightGBM) with Shapley additive explanations (SHAP) to explore these effects with the consideration of the built environment and metro network topology. Results show that the collective impacts of intermodal connection are positive, not only within the main city but also alongside the main commuting corridors, while negative effects occur in the peripheral area. Specifically, bike sharing trips increase metro ridership within the inner ring of the city, while bus services lower metro usage at stations alongside the elevated ring roads. Parking facilities enable metro usage at city sub-centers, and the small pedestrian catchment area increases metro riders alongside the main commuting corridors. Empirical findings help policymakers understand the effect mechanism of intermodal connection for stations in different regions and prioritize customized planning strategies.

Subjects judged which one of two patterns, a visual or a tactile pattern, had been presented first. The visual and tactile displays were placed in close spatial proximity. The patterns appeared to move across their respective displays. Although irrelevant to the temporal order judgment (TOJ), the direction of motion of the patterns—the trajectory—affected the judgments. When the leading pattern was moving towards the trailing pattern (consistent movement), subjects tended to judge it, correctly, as leading. When the leading pattern was moving away from the trailing pattern (inconsistent movement), subjects tended to judge it, incorrectly, as trailing. Changing the spatial position of the arrays such that the pattern trajectories were no longer towards one another eliminated the effect of movement on TOJs. Although there was a substantial difference in performance on consistent and inconsistent trials, there were no differences in subjects' ratings of their performances. The results demonstrate that the trajectory effect can be obtained multimodally. The issues whether the effect of motion alters the perceived temporal separation between the visual and tactile patterns, and whether the visual and tactile patterns are represented by a common framework, are discussed.

Notre cerveau génère continuellement des mouvements oculaires saccadiques et maintient leur précision grâce à l'adaptation saccadique (AS). Bien que l’AS ait été largement étudiée depuis la fin du 20ᵉ siècle, de nombreuses questions restent ouvertes. Par exemple, en plus des cibles visuelles, les saccades peuvent également être effectuées vers des stimuli somatosensoriels et auditifs, mais on ne sait pas si ces ‘saccades non visuelles’ peuvent être adaptées comme les ‘saccades visuelles’. Dans la première partie de cette thèse, nous avons étudié la possibilité de modifier l'amplitude des saccades vers des cibles tactiles (Étude 1) et auditives (Étude 2) via le paradigme du double saut de cible, largement utilisé pour adapter les saccades visuelles (McLaughlin, 1967). Nous avons également étudié le transfert bidirectionnel et intermodal de l'AS entre les saccades réactives (SR) visuelles et tactiles, ainsi qu'entre les SR visuelles et auditives, respectivement. Nos résultats montrent que les saccades tactiles et auditives peuvent être adaptées d’une manière similaire aux SR visuelles. Cependant, les transferts étaient asymétriques : l'adaptation des SR visuelles transfère complètement aux saccades non adaptées tactiles et auditives, tandis que pour l'adaptation des SR tactiles et auditives, malgré leur généralisation aux saccades non adaptées de la même modalité, le transfert aux SR visuelles n’est que partiel. D'une part, le transfert complet de l'adaptation des SR visuelles soutient l'hypothèse actuelle d'un niveau moteur de l'adaptation de ces saccades. D'autre part, les faibles transferts d'adaptation vers les SR visuelles suggèrent l'existence de sites d'adaptation spécifiques aux SR non visuelles, situés en amont de la voie motrice finale commune à toutes les saccadies. La première partie de cette thèse montre que l'AS peut être déclenchée dans l'obscurité, sans information visuelle sur la position post-saccadique de la cible. Cela semble contredire les théories actuelles sur la nature des signaux d'erreur responsables de l'AS, qui reposent toutes sur ce feedback visuel post-saccadique. Un facteur potentiel qui pourrait servir de signal d'erreur pour l'AS est le locus de l'attention spatiale, comme le suggèrent certaines études précédentes. L'orientation covert (sans mouvement des yeux) de l’attention et les saccades contribuent ensemble à la perception visuelle et impliquent des substrats neuronaux communs. De plus, de récentes études montrent que l'AS module l'orientation de l'attention spatiale, tandis que l'effet inverse, de l'attention spatiale sur l'AS, reste indéterminé. Dans la deuxième partie de cette thèse (Étude 3), nous visons à évaluer en profondeur l’effet modulateur de l'attention spatiale sur l'AS. Nous avons utilisé une combinaison du paradigme du double saut de cible (pour induire l'adaptation) et du paradigme d'orientation intermodale de l’attention pour étudier l'effet de l'attention spatiale exogène et endogène tactile sur l'adaptation des saccades réactives et volontaires, respectivement. Nos résultats montrent des corrélations significatives entre l’adaptation (taux et vitesse) et la quantité d'attention allouée vers ou à l'opposé de la cible saccadique adaptée. Ainsi, l'Étude 3 apporte des arguments supplémentaires en faveur d'un couplage entre l'attention spatiale et l'AS, possiblement via un effet de l'attention spatiale sur les signaux d'erreur saccadique au niveau du cortex pariétal postérieur. Ce travail apporte de nouvelles perspectives sur le contrôle de la précision des SR non visuelles et met en lumière le rôle de l'attention spatiale dans l'AS. Bien que des progrès significatifs aient été réalisés par les modèles étudiant la nature des signaux d'erreur qui conduisent à l'AS, ces derniers ne prennent actuellement pas en compte le couplage entre l'attention spatiale et l'AS, ce qui devrait être le sujet de travaux futurs
Our brain continuously generates saccadic eye movements and maintains their accuracy thanks to saccadic adaptation (SA). Despite this plasticity-based mechanism has been widely studied since the late 20th century, many questions remain unanswered. For instance, in addition to visual targets, saccades can also be performed toward somatosensory and auditory stimuli, but whether these ‘non-visual saccades’ can be subject to similar adaptive mechanisms as visual saccades is unknown. In the first part of this thesis, we investigated the possibility of adapting the amplitude of reactive saccades (RS) to tactile (Study 1) and auditory targets (Study 2) via the double target step paradigm, which has largely been used to induce adaptation of visual saccades since its introduction (McLaughlin 1967). We also investigated the bidirectional cross-modal transfer of adaptation between visual and tactile saccades, as well as between visual and auditory saccades, respectively. Our results revealed that tactile and auditory saccades can be adapted in much the same way as visual saccades. However, the transfer patterns were asymmetric: visual SA transferred fully to non-adapted tactile and auditory saccades, whereas tactile and auditory SA, despite complete generalization to saccades of the same modality but toward non-adapted locations, transferred only partially to the non-adapted visual saccades. On the one hand, the full transfer of visual saccades adaptation further supports the current view of a motor adaptation locus for visual RS. On the other hand, the low adaptation transfers to visual saccades suggest the presence of adaptation loci specific to non-visual RS and situated upstream of the final motor pathway common to all saccades. Interestingly, both studies also demonstrate that SA can be elicited in darkness, thus, without the vision of the post-saccadic target location. This seems to contradict current theories on the nature of error signals driving adaptation, which all rely on post-saccadic visual feedback. One potential factor that might serve as an error signal for SA is the locus of spatial attention, as suggested by some previous studies. Spatial attention oriented covertly (no eye movement) and saccadic orienting responses both critically contribute to visual perception and involve overlapping neural substrates. In addition, recent studies show that SA modulates the orienting of spatial attention while the reverse effect, that is, the effect of spatial attention on SA, remains unsettled. In the second part of this thesis (Study 3), we aim to assess in depth the possibility of a modulatory effect of spatial attention on SA. We used a combination of the double-step target paradigm (to induce adaptation) and the cross-modal attentional-orienting paradigm to investigate the effect of tactile exogenous and endogenous spatial attention on the adaptation of reactive and voluntary saccades, respectively. Our results show significant correlations between the amount and speed of saccadic adaptive changes and the amount of attention allocated toward or away from the adapted saccade target. Thus, Study 3 brings additional arguments in favor of a coupling between spatial attention and SA, possibly by means of an effect of spatial attention on the saccadic error signals at the level of the posterior parietal cortex. Overall, this work brings additional empirical insights on the control of accuracy of non-visual RS and further highlights the role of spatial attention in SA. Even though significant advances have been seen in models investigating the nature of the error signals driving SA, they currently do not consider the coupling between spatial attention and SA. Therefore, based on the available literature and the outcomes of this thesis, we suggest that future work should take into account the role of spatial attention in error processing

L'intégration de l'information sensorielle est au centre de nombreux travaux en psychologie cognitive. Dans ce travail, nous considérons cette question sous l'angle des interactions intermodales entre vision (V) et toucher (T). Deux types d'appariements sont étudiés : les transferts intramodaux, qui correspondent aux situations de reconnaissance classique au cours desquelles le sujet explore des cibles dans une modalité sensorielle puis doit les reconnaître dans une modalité différente. Ce dernier type d'épreuve nécessite soit une traduction des informations d'un code sensoriel vers un autre (traitement modal), soit la mobilisation d'un code unique commun aux différents sens (traitement amodal). Les études que nous avons menées portent plus précisément sur les effets de l'âge et de la condition de transfert sur les performances, intervenant au cours du développement et du vieillissement. Trois expériences ont été réalisées. La première étude, à laquelle ont participé quatre vingt quinze sujets (enfants, adultes, jeunes et âgés), contraste deux situations de transferts à entrée visuelle, la première correspond à un transfert intramodal (V-V) et la seconde à un transfert intermodal entre vision et touché (V-T). Cent treize personnes (enfants, adultes jeunes et âgés) ont participé à la deuxième expérience qui porte sur les transferts à entrée tactile et contraste deux conditions, l'une de transfert intramodal (T-T) et l'autre de transfert intermodal (T-V). Les résultats de ces deux premières études indiquent un effet significatif du facteur âge sur les performances des sujets, les jeunes adultes obtenant des scores supérieurs aux autres groupes de sujets. De plus, les résultats indiquent un effet significatif de la condition de transfert sur les performances des sujets, allant dans le sens d'une supériorité des performances à entrée visuelle. La troisième expérience porte sur les processus cognitifs susceptibles de médiatiser l'effet de l'âge sur les performances de transfert dans les conditions T-T et T-V. Quarante sujets adultes, jeunes et âgés ont participé à cette étude. Les résultats de cette dernière montrent que des processus différents interviennent dans chaque condition. D'une part, la vitesse de traitement médiatise les effets de l'âge dans la situation intramodale T-T. D'autre part, les facteurs "mémoire de travail verbale" et "imagerie mentale" médiatisent les effets de l'âge sur le transfert intermodal T-V. Ce travail montre que les processus impliqués dans le transfert d'information sensoriel se modifie au cours de la vie. Il indique également que différents facteurs cognitifs sont impliqués selon la nature des transferts réalisés (intramodal ou intermodal) et l'âge des sujets considérés
The sensory information integration concern several studies in cognitive psychology. In this work, we focus on the question of intramodal and cross modal interactions between vision (V) and touch (T). Two types of matching are studied : the first correspond to a classical recognition task in which objects are explored and recognized using the same sensory modality. The second concern cross modal transfer, in which participants explore the target with a modality and recognize it using another modality. This type of task require the information to be translated from a sensory modality to the other (amodal integration), or the use of a single code which is common to different senses (modal integration). Our studies focus on age effect and transfer condition effect on subject's performances, from childhood to elderly. Three experiments were carried out. The first concern 95 subjects (children, young and old adults) took part in the second experiment which concerns two transfers with tactual exploration (T-T and T-V). The results of these two studies indicate a significant age effect on performances, young adults obtain better scores than other groups. Moreover, results indicate a significant transfer condition effect on performances : scores are better when vision is used during the exploration phase. The third esperiment focus on cognitive processes that are plausibly mediate age effect on T-T and T-V conditions. 40 participants (young and old adults) took part in this study. The results show that different processes are involved in each condition. Integration speed mediate age effect in T-T condition, working memory and mental imagery mediate age effect in cross modal transfer T-V condition. This study show that sensory information transfer process changes along life and indicates that different cognitive factors are involved in this process according to transfer condition and people condition and people age-linked experience

Le syndrome de Turner (ST) est une maladie génétique affectant exclusivement les sujets féminins, caractérisé par l'absence totale ou partielle d’un des chromosomes X. Notre étude, d'ordre clinique et expérimental, vise à analyser le phénotype neuropsychologique de ces patientes en nous centrant sur le traitement intermodal que nous confrontons au traitement unimodal. Cette approche est complétée par l'analyse de l'efficience intellectuelle, des fonctions exécutives, du traitement visuo-spatial, de la reconnaissance des émotions faciales et de la sphère psychoaffective. La population est constituée de 12 sujets ST âgés de huit à cinquante ans, appariés à 60 sujets contrôles. La méthodologie s'appuie sur un protocole expérimental de 28 épreuves dont la plupart sont informatisées et chronométrées. Les résultats discutés à la lumière de données récentes en imagerie cérébrale apportent des informations nouvelles sur le phénotype cognitif de cette pathologie et affinent notre compréhension des capacités d'intégration d'informations multimodales chez des sujets sains. Nous montrons que le profil ST comporte deux dissociations et que l'empan mnésique auditivo-verbal est défaillant. Le traitement intermodal est marqué par une lenteur significative que l'on retrouve sélectivement au niveau unimodal. L'intermodalité permet cependant d'accélérer le temps de traitement des sujets ST et d'améliorer leurs scores dans certains registres. Ce constat ouvre une voie de réflexion en matière de remédiation cognitive en regard de la plasticité neuronale
Turner syndrome (TS) is a neurogenetic disorder affecting exclusively females. It is characterized by the complete or partial absence of one X chromosome. The clinical and experimental study presented here aims at analyzing the neuropsychological phenotype of Turner patients by focusing on the cross-modal processing in comparison with one-mode processing. The analysis is completed by intellectual efficiency, executive and visuospatial functions, emotional facial expression identification and of psychosocial aspects. We tested 12 eight to fifty year-old Turner subjects matched with 60 control subjects, using 28 tests most of which were computerized and timed. The results discussed in light of recent functional imaging data bring new information on the ST cognitive phenotype and refine our understanding of multimodal information integration processing to healthy subjects. We show two dissociations and the impairment of the verbal digit span in TS cognitive profile. The cross-modal processing is marked by a significant slowness selectively found in one-mode processing. However the cross-modal processing improves the reaction time of the TS subjects and their scores in certain areas. This report opens a way of reflection about cognitive remediation according to the neuronal plasticity

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Which is better, a visual or an auditory warning signal? Initial findings suggested that an auditory signal was more effective, speeding reaction to a target more than a visual warning signal, particularly at brief foreperiods [Bertelson, P., & Tisseyre, F. (1969). The time-course of preparation: confirmatory results with visual and auditory warning signals. Acta Psychologica, 30. In W.G. Koster (Ed.), Attention and Performance II (pp. 145-154); Davis, R., & Green, F. A. (1969). Intersensory differences in the effect of warning signals on reaction time. Acta Psychologica, 30. In W.G. Koster (Ed.), Attention and Performance II (pp. 155-167)]. This led to the hypothesis that an auditory signal is more alerting than a visual warning signal [Sanders, A. F. (1975). The foreperiod effect revisited. Quarterly Journal of Experimental Psychology, 27, 591-598; Posner, M. I., Nissen. M. J., & Klein, R. M. (1976). Visual dominance: an information-processing account of its origins and significance. Psychological Review, 83, 157-171]. Recently [Turatto, M., Benso, F., Galfano, G., & Umilta, C. (2002). Nonspatial attentional shifts between audition and vision. Journal of Experimental Psychology; Human Perception and Performance, 28, 628-639] found no evidence for an auditory warning signal advantage and showed that at brief foreperiods a signal in the same modality as the target facilitated responding more than a signal in a different modality. They accounted for this result in terms of the modality shift effect, with the signal exogenously recruiting attention to its modality, and thereby facilitating responding to targets arriving in the modality to which attention had been recruited. The present study conducted six experiments to understand the cause of these conflicting findings. The results suggest that an auditory warning signal is not more effective than a visual warning signal. Previous reports of an auditory superiority appear to have been caused by using different locations for the visual warning signal and visual target, resulting in the target arriving at an unattended location when the foreperiod was brief. Turatto et al.'s results were replicated with a modality shift effect at brief foreperiods. However, it is also suggested that previous measures of the modality shift effect may still have been confounded by a location cuing effect.

The author maintains that American politics, institutional arrangements, and political culture have prevented the development of a comprehensive, integrated, intermodal transportation policy in the United States. Dilger makes his argument by examining the development of the national governmental authority in both surface and air transportation. Each transportation mode—highways/mass transit, Amtrak, and civilian air transportation—is examined separately, assessing their development over time and focusing on current controversies, including, but not limited to, the highway versus mass transit funding issue; the recent decentralization of decision making authority on surface transportation policy; Amtrak's viability as an alternative to the automobile; and current antiterrorist policies' effect on transportation policy.

The electrooptic effect is used in a few-mode fiber to control intermodal interference. The fiber has internal electrodes and is poled to increase its electrooptic coefficient. The response time is in the nanosecond range.

Practically all nonlinear frequency degenerate four wave mixing processes reported previously for the bulk photorefractive materials have been observed also in the planar photorefractive waveguides: interaction of two beams with the same (or with the different) mode indices resulting in the developement of the dynamic grating, phase conjugation due to the backward wave mixing, polarization conversion, etc.[1]. Specific properties of the waveguides, as, e.g., the existance of several propagation modes with the same frequency but different propagation velocities, make possible same additional nonlinear wave mixing effects which do not occure in bulk samples. We report the first to our knowlage observation of such effect-the nonlinear parametric mixing of different waveguide mode and parametric intermode scatering.

The launching efficiency (η) from semiconductor lasers into plane-ended (PE) multimode fibers is low(~10 20%). We polished PE into rooftop (RT) ends, having a RT angle of 65° to the fiber axis, and observed a substantial increase in η; 27% (PE) to 51 % (RT). This was achieved (ηmax) after optimizing the apex position of RT fiber with respect to the stripe; the two have to be parallel. When they were perpendicular, ηmin = 29% was obtained. The effect of longitudinal, lateral, and angular misalignments was compared for the PE and RT ends; the latter were always more critical. We further investigated, for the first time, the effect on the intermodal pulse dispersion and obtained the following results: (i) output FWHM after 1 m having PE or RT end was 0.57 ns, (ii) FWHM after 1 km with PE input was 0.70 ns, giving pulse dispersion (t m ) of 0.41 ns, (iii) FWHM after 1 km with RT input and r/max was 0.61 ns giving t m = 0.22 ns, (iv) FWHM after 1 km with RT end and ηmin was 0.65 ns giving t m = 0.31 ns. The material dispersion was negligible. Hence comparing (ii) and (iii) above, t m was reduced by a factor of 2. This was explained by alteration of the modal power distribution in fiber core and confirmed by output far-field measurements.

The European Union (EU) transport policy recognizes the importance of the waterborne transport systems as key elements for sustainable growth in Europe. By 2030, 30 % of total road freight over 300 km should shift to rail or waterborne transport, and more than 50 % by 2050. Thus far, this ambition has failed. Horizon 2020 project AEGIS (for Advanced, Efficient and Green Intermodal Systems) proposes a new waterborne transport system for Europe that is green, robust, flexible, more automated and autonomous, and able to connect both rural and urban terminals. The purpose of this paper is to describe work and preliminary results from this project. To that effect, and in order to assess any solutions contemplated in AEGIS, a comprehensive set of Key Performance Indicators (KPIs) have been defined, and three specific use cases within in Europe are defined and evaluated according to these KPIs. KPIs represent the criteria under which the set of solutions developed under AEGIS are evaluated, and also compared to non-AEGIS solutions. They are grouped under economic, environmental and social KPIs. KPIs have been selected after a consultation process involving AEGIS partners and external Advisory Group members.

Forward stimulated Brillouin scattering (FSBS) is similar in physical origin to conventional backward SBS (BSBS), except that it occurs in a forward direction between two nondegenerate copropagating optical modes of a dual-mode optical fiber.1 FSBS may, however, be the only example of a nonlinear effect where the threshold falls as the mode spot size is increased. This curious behavior is a consequence of the fact that the acoustic gain depends on an electrostrictive moment and not (as in conventional SBS) a pressure. Intermodal beating between an LP01 and a frequency shifted LP11 mode gives rise to a moving interference pattern with regions of constructive interference that alternate across the core. In the correct matching conditions, electrostriction will feed optical energy into a flexural mode of the fiber. The results of a theoretical study of FSBS are presented, including calculations of the threshold power (only weakly dependent on the laser linewidth, owing to the copropagating nature of the process) with a discussion of the novel phenomenology caused by long phonon lifetimes. We also show how the theory may be used to design special fibers in which the FSBS threshold power is many times smaller than in BSBS.

We describe a phase-locking technique for combining two and three separate commercial laser diodes (Hitachi 1400) by using phase conjugate injections. The injections come from a double phase conjugation mirror (DPCM). The photorefractive crystal is a single crystal of BaTiO3. Two phase-locking schemes were experimentally demonstrated: unidirectional injection and bidirectional mutual injection. Because the phase conjugate wave is backward going, this injection is more effective. Only a fraction of a microwatt injection from the DPCM is sufficient for phase locking. The visibility of the interference fringe between the two locked lasers is about 0.95. For the unidirectional phase conjugate injection, the curve of the dependence of locking bandwidth on the injection power was measured. The intermodal injection locking was studied. In this case the mode-coupling effect was included in the coupled wave equations. Our theoretical curve is in agreement with the experimental results. For the bidirectional phase conjugate mutual injection, the phase locking between two lasers is stable only when the injection level is less than −40 dB. When the injection level is larger than −30 dB, the output spectra of the lasers are broadened and the case is driven into multimode operation.

Abstract This paper investigates the parameters that influence the structural response of typical wide nose locomotive short hoods involved in offset collisions. This accident scenario was chosen based upon the railway collision that occurred in Selma, North Carolina, on May 16, 1994. A raised overhanging intermodal trailer on a freight car struck the front of the oncoming passenger locomotive. The objective of the study is to determine the current baseline level of crashworthiness of locomotive hood structures and the potential effectiveness of stronger corner structures. The key issues addressed are: degree of overlap, material and thickness combinations, obliquity, and crush response dependence on initial impacting speed. For a raised offset collision where the intruding body is far away from any support structures, an analytical expression is developed to predict the mean crush force. Comparisons of the results with finite element calculation are favorable. The scenarios involving obliquity, and different initial impacting speeds are investigated using non-linear large deformation finite element analyses. Key results are: obliquity has little effect on the mean crush force for short penetration distances; increased material thickness improves crashworthiness performance; initial impacting speed does not dramatically alter mean crush loads predicted for large offsets away from supports; and the distances from supporting structures have a significant effect of the predicted mode of failure and hence predicted mean crush loads. The results of the study show that it is possible to dramatically increase the crashworthiness responses of short hood structures with minor increases in weight while staying within the original design volume envelope.