通过形状差异修正模式方法进行的损伤识别试验(英文)

An experimental program was undertaken to test the feasibility to detect the occurrence of structural damage using a modified mode shape difference technique. The vibration response of a steel beam fixed at one end and hinged at the other was obtained for the intact and damage conditions. Modal analysis was performed to extract the frequencies and mode shapes. The method shows a good potential in detection of occurrence and location of damage.     

Can rural older drivers meet their needs without a car? Stated adaptation responses from a GPS travel diary survey

Rural seniors are highly dependent on their automobile to meet their trip making needs, yet the effects of aging can make access to the vehicle difficult or impossible over time. The anticipated growth in the older person population, in concert with limited travel data available to support rural transportation planning in Canada suggests a disconnect between what rural older people may require for transportation and the availability of formal alternatives. Many will seek informal alternatives to driving, such as depending on friends and family, to meet their travel needs, but the degree is not well understood in the context of their actual vehicle usage and stated ability to adapt. This paper draws from a Global Positioning System (GPS)-based multi-day travel diary survey of a convenience sample of 60 rural older drivers (29 men, 31 women, average age of 69.6 years) from New Brunswick, Canada. Participants would rely on “friends and family” for 52% of all trips they undertook as driver in the survey, “walk or bike” for 14% of trips, and “not take the trip” in 34% of trips if they did not have access to a vehicle. The formal option of “Transit” was not selected as a viable alternative by any participant for any trip. “Medical trips”, “Shopping” and “Personal Errands” were the least discretionary of all trip types, yet the most difficult for participants to find alternate arrangements. This suggests the need to explore different models of service delivery, such as a community-supported, member-based rural shuttle service with volunteer and paid drivers that build on informal social networks and can provide service when friends and family are unavailable.     

Correcting for endogeneity in behavioral choice models with social influence variables

While psychologists and behavioral economists emphasize the importance of social influences, an outstanding issue is how to capture such influences in behavioral models used to inform urban planning and policy. In this paper we focus on operational models that do not require explicit knowledge of the individual networks of decision makers. We employ a field effect variable to capture social influences, which is calculated as the percent of population in the peer group that has chosen the specific alternative. We define the peer group based on socio-economic status and spatial proximity of residential location. As in behavioral economics and psychology, the concept is that one is influenced by the choices made by one’s peers. However, using such a social influence variable in a behavioral model causes complications because it is likely endogenous; unobserved factors that impact the peer group also influence the decision maker, yielding correlation between the field effect variable and the error. The contribution of this paper is the use of the Berry, Levinsohn, and Pakes (BLP) method to correct the endogeneity in a choice model. The two-stage BLP introduces constants for each peer group to remove the endogeneity from the choice model (where it is difficult to deal with) and insert it into a linear regression model (where endogeneity is relatively easier to deal with). We test the method using a mode choice data set from the Netherlands and readily available software and find there is an upward bias of the field effect parameter when endogeneity is not corrected. The procedure outlined presents a practical and tractable method for incorporating social influences in choice models.     

Hydrodynamic response of a non-ship-shaped FPSO vessel with damping plates

Experimental and numerical hydrodynamic investigations were carried out on a 1:45 scale model of a novel non-ship-shaped floating, production, storage, and offloading (FPSO) vessel that has been designed for use in the icy waters of the Arctic as well as the severe sea states of the North Sea. This FPSO vessel has a turret mooring system that is disconnectable during emergencies and inclement weather conditions. Experiments were conducted on a 1:45 scale model of the FPSO with damping plates consisting of skirt plates and different sizes of keel plates in order to study their influence on the response of the vessel. A numerical study of the scale model was carried out using the Wave Analysis at Massachusetts Institute of Technology code, and the results provided by it were compared with those obtained from model tests in the wave basin.     

Possible experimental method to determine the suspension parameters in a simplified model of a passenger car

Currently, as well as in the past, researchers have shown great interest in developing suspension systems for vehicles and especially in the design and optimization of the suspension parameters, such as the stiffness and the damping coefficient. These parameters are considered to be important factors that have an influence on safety and improve the comfort of the passengers in the vehicle. This paper describes a simplified methodology to determine, in a quick manner, the suspension parameters for different types of passenger cars equipped with passive suspension systems. Currently, different types of passenger cars are produced with different types of suspension systems. Finding a simplified methodology to determine these parameters with sufficient accuracy would contribute a simplified and quick method to the inspection of the working conditions of a suspension system. Therefore, a simple system to determine these parameters is needed. An analysis of the suspension parameters is performed using mathematical modeling and numerical analysis conducted using the Working Model software. The result derived from the developed methodology shows small errors when compared with the generic values, and it can be concluded that the design of the suspension parameter measurement device using the developed methodology is useful, simple, and has sufficient accuracy.     

Safety-oriented bicycling and traffic accident involvement

Many U.S. bicyclists are killed or injured in traffic accidents annually. Based on analysis of available research and published reports on traffic accidents, it was theorized that adherence to six safety-oriented on-road bicycling practices will reduce involvement in traffic accidents. This study investigated whether adherence to these safety-oriented bicycling practices is associated with reduced involvement in traffic accidents. U.S. adult bicycle riders responded to an anonymous on-line survey covering bicycling practices, recent traffic accident experiences, and potential confounding variables. Participants were recruited via on-line announcements to bicycling-related organizations. The results suggested that neither vigilance nor cautiousness will protect adult bicycle riders from traffic accident involvement, but predictability might reduce accident risk, particularly for younger adults. Results should be interpreted cautiously due to limitations in the study methodology. Further research of this type is warranted.This paper is a re-formulation of research originally presented as a conference paper and oral presentation at the International Cycling Safety Conference in Bologna, Italy, 3–4 November 2016.     

从凸缘连接到对焊接头的飞跃:应用于汽车制造业的激光器

如果将对焊接头取代于横梁、底座和管道的凸缘和搭接接头以及其他车身上结构件的焊接,能节省多少材料、重量和燃料?当粘合车门钣金件和汽车框架的密封胶水重量包含在总重量中,这个问题就非常值得一提。而这个问题取决于零部件。如果不再使用凸缘搭接,减少的重量能高达几公斤,同时也能节省每部分的安装空间,约高达8～16mm。搭接凸缘设计是两项极具现代车身制造特色的发明逐渐成熟的产物。第一项是诞生于1877年的电阻焊,它是快速、高效和实用的焊接加工方法。第二项是1 954年应     

Book review

Recreation: Marine Promise, Proceedings of the National Conference on Marine Recreation Susan H. Andersen, Ed., October 2–4, 1975, Newport Beach, California

Parable Beach: A Primer in Coastal Zone Economics by J. W. Devanney III, G. Ashe, and B. Parkhurst, The MIT Press, 1976, 99 pp.

Marine Recreational Fisheries, Proceedings of the First Annual Marine Recreational Fisheries Symposium Henry Clepper, ed., New Orleans, Louisiana, February 27, 1976.     

Inclusion of speed and weather measures in safety performance functions for rural roadways

The research on relationships among vehicle operating speed, roadway design elements, weather, and traffic volume on crash outcomes will greatly benefit the road safety profession in general. If these relationships are well understood and characterized, existing techniques and countermeasures for reducing crash frequencies and crash severities could potentially improve, and the opportunity for new methodologies addressing and anticipating crash occurrence would naturally ensue. This study examines the prevailing operating speeds on a large scale and determines how traffic speeds and different speed measures interact with roadway characteristics and weather condition to influence the likelihood of crashes. This study used three datasets from Washington and Ohio: 1) Highway Safety Information System (HSIS), 2) the National Performance Management Research Dataset (NPMRDS), and 3) National Oceanic and Atmospheric Administration (NOAA) weather data. State-based conflated databases were developed using the linear conflation of HSIS and NPMRDS. The results show that certain speed measures were found to be beneficial in quantifying safety risk. Annual-level crash prediction models show that increased variability in hourly operating speed within a day and an increase in monthly operating speeds within a year are both associated with a higher number of crashes. Safety practitioners can benefit from the current study in addressing the issue of speed and weather in crash outcomes.     

The vagrant ethic: Need for a sea-lane philosophy

Although considerable progress has recently been made in the evolution of marine traffic procedures in coastal and waterway areas, mariners are finding difficulty in coping with the diverse traffic schemes that have so far been devised. This paper is a plea for international and logical marine traffic management, so that ships can operate safely and efficiently within a framework of the proliferating offshore zonal legislation that we are now witnessing.