应用碟片激光器和光学扫描仪进行遥控焊接

采用YAG激光器进行固体焊接，已成为汽车制造过程中一项成熟可靠的工艺。该项工艺现广泛用于车身和车架制造、传动系统制造、车座制造和其它领域。     

Distribution of dinoflagellate cysts in surface sediments of the Mackenzie Shelf and Amundsen Gulf, Beaufort Sea (Canada)

In order to document long-term climate cycles and predict future climate trends for the Arctic, we need to look at the geological records to establish the link between historical and pre-historical sea-surface parameters. Dinoflagellate cysts (dinocysts) are used as proxy indicators of sea-surface parameters (temperature, salinity, sea-ice cover, primary productivity) jointly with transfer functions and a modern dinocyst reference database, to reconstruct the evolution of sea-surface conditions at decadal and millennial timescales. Here we present the surface distribution of recent dinocyst assemblages from 34 surface sediment samples collected on the Mackenzie Slope/Amundsen Gulf during the 2004 CASES (Canadian Arctic Shelf Exchange Study) cruise. Dinocyst concentrations in surface sediments are relatively high outside the Mackenzie plume area and increase gradually eastward toward Amundsen Gulf. The cysts of autotrophic dinoflagellates are dominant throughout the study area, while the maximum abundance of heterotrophic taxa is found within the Mackenzie plume. Hierarchical clustering analyses allowed defining two dinocyst assemblages. Assemblage I is located on the Mackenzie Slope and southern Amundsen Gulf, while Assemblage II is located within the Cape Bathurst Polynya area in northern Amundsen Gulf. Both assemblages are dominated by Operculodinium centrocarpum, but are distinguished on the basis of the relative abundance of Islandinium minutum, a taxon generally associated with sea ice. I. minutum is found in lower abundance in the Cape Bathurst Polynya.     

Travelers’ compliance with social routing advice: evidence from SP and RP experiments

Transportation - This study examines to what extent travel information can be used to direct travelers to system-optimal routes that may be sub-optimal for them personally, but contribute to...     

我的备用车是蝙蝠战车

德文GTX勇闯哥谭镇嘿,你是蝙蝠侠?一阵外来客的叫嚷声从一辆敞篷观光巴士的上层传来。人们纷纷向停在路边的跑车行注目礼,车身如钢琴漆般亮黑,像极了蝙蝠侠的座驾。斯科特·德文觉得开这玩笑的人真是够糊涂,他抬头瞥了一眼巴士顶上的露天座位,进出一个电力达上千瓦的微笑,然后毫无表情地说:对,我就是。     

Determination of anthropogenic CO2 in the North Atlantic Ocean using water mass ages and CO2 equilibrium chemistry

A new method to calculate the anthropogenic CO₂ (ΔDIC_ant) within the water column of the North Atlantic Ocean is presented. The method exploits the equilibrium chemistry of the carbonate system with reference to temperature, salinity and the partial pressure of atmospheric CO₂ (pCO_2,atm). ΔDIC_ant is calculated with reference to the ventilation ages of water masses derived from tracer data and to the time history of pCO_2,atm. The method is applied to data recorded during the WOCE program on the WHP A1/E transect in the North Atlantic Ocean, where we characterise six key water masses by their relationships of dissolved inorganic carbon (DIC) and apparent oxygen utilisation (AOU). The error in determining ΔDIC_ant is reduced significantly by minimising the number of values referred to, especially by avoiding any use of remineralisation ratios of particulate organic matter. The distribution of ΔDIC_ant shows highest values of up to 45 μmol kg⁻¹ in the surface waters falling to 28–33 μmol kg⁻¹ in the Irminger Sea west of the Mid-Atlantic Ridge. The eastern basin is imprinted by older water masses revealing decreasing values down to 10 μmol kg⁻¹ ΔDIC_ant in the Antarctic Bottom Water. These findings indicate the penetration of the whole water column of the North Atlantic Ocean by anthropogenic CO₂.     

Evaluating erosion susceptibility for land‐use planning in coastal watersheds

Abstract

This paper reports on research conducted in support of a coastal zone management effort to reduce erosion and sedimentation impacts in a wetland watershed, Elkhorn Slough, Monterey County, California. The research reviews methods of determining soil erosion susceptibility and relating it to land‐use intensity within the watershed, measured by a land disturbance index. Erosion susceptibility is measured in three ways: by a combination of slope and the erosion factor of the Universal Soil Loss Equation; by field measurement of erosion and deposition on selected sites; and by computer‐assisted terrain analysis of data from secondary sources. Land use is shown to be a more important factor than landform in influencing relative erosion susceptibility.     

Identification of occupant posture using a Bayesian classification methodology to reduce the risk of injury in a collision

Recent studies have shown that smart restraint systems, which will recognize and then adapt to a specific collision and occupant combination, have a strong opportunity to significantly reduce occupant injuries during a traffic accident. As a step toward the development of these adaptive restraint systems, this study proposes a novel methodology for the classification of pre-crash occupant posture. Various occupant postures were simulated with a human model and the corresponding data was recorded using sensor models implemented in a mid-size car interior. The sensor data was then used to train two Bayesian classifiers which categorized an unknown occupant posture as one of nine predefined classes. The posture classifiers and a look-up table which contained optimized restraint laws for each class were combined to form catalog controllers for the restraint systems. The benefit of these restraint systems with catalog controllers vs. a restraint system optimized at a nominal posture was estimated by analyzing crash simulations with the occupant in 200 different postures. While the minimum error rate classifier showed the highest correct classification rate (90%), the Bayesian minimum risk classifier estimated the highest average injury reduction (21%). As expected, the highest injury reduction (up to 45%) was recorded for the posture classes closest to the windshield, whereas the lowest injury reduction was found for the classes closest to the nominal position. While the proposed restraint system with a catalog controller requires considerable “offline” computational effort, it is more versatile in terms of using complex human models and injury criteria and is much faster during the brief decision window available than recent “online” controllers proposed previously in literature.     

Extended gate operations at the ports of Los Angeles and Long Beach: a preliminary assessment

The paper examines the implementation of extended gate operations at the Los Angeles/Long Beach ports. The programme, known as PierPASS, assesses a Traffic Mitigation Fee (TMF) on eligible containers moved into and out of the ports during peak hours. The fees are intended to defray the costs of extended operations at the ports.

In this paper we focus on the implementation of the programme and its outcomes over a year of operation. We discuss the motivations and actions of key stakeholders and place our examination in the institutional framework of the goods movement supply chain. Our results are based primarily on a series of extended interviews with stakeholders, together with data provided by PierPASS and by three drayage trucker surveys. We find that the PierPASS programme was a response by terminal operators and steamship companies to growing political pressure. Given their market power within the supply chain, they were able to create a programme that protected their interests yet responded to political imperative. The PierPASS programme has been a success: the peak fee has shifted a significant share of cargo to evenings and weekends, as intended. Winners and losers of PierPASS reflect the larger structure of the international supply chain.