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731.
Young men in coastal Tanzania are often blamed for damaging marine habitats by engaging in unsustainable and destructive fishing practices, including dynamite fishing, but their perceptions have not been sufficiently documented. While marine scientists, international environmental NGOs, and activists have called attention to the destructive fishing practices’ devastating impacts, insights into the contextual factors that motivate those who engage in dynamite fishing are limited. Additionally, risk perceptions and concerns regarding the environmental impact and dangers of dynamite fishing among the youth are also understudied. This paper provides ethnographic insights into the historical and contextual factors underlying dynamite fishing in rural coastal Mtwara. It draws on ethnographic data gathered through participant observation, focus group discussions and in-depth interviews with residents from two neighboring coastal villages – one located inside a marine protected area (MPA), and another located outside the MPA’s boundary. The paper first examines the views of elderly men and women to provide the historical context of dynamite fishing in coastal Mtwara. It then juxtaposes youth perceptions regarding marine conservation and dynamite fishing in the two villages, vis-à-vis ongoing efforts to curb destructive fishing practices and to enhance marine biodiversity and ecotourism in the region. Results of the study reveal that unresolved tensions between the MPA authorities and local fishers surrounding enforcement practices and unfulfilled gear-exchange-related promises, and allegations of poor governance, are important contextual factors in the persistence of dynamite fishing. The paper concludes by articulating possible remedial measures to mitigate the tensions between youth concerns about their livelihoods, and the goals of marine biodiversity conservation as a way forward in preventing dynamite fishing.  相似文献   
732.
针对洛阳机务段发生的HXD3型机车6A系统轴箱轴承报警故障,通过分析驱动装置及轴箱轴承结构特点、6A系统报警数据,以及轴承解体情况,找到轴箱轴承外滚道剥离的原因,并提出相应的预防措施和建议。  相似文献   
733.
Journal of Marine Science and Technology - This paper presents a procedure for the estimation of propeller effective wakes in oblique flows. It shows how a recently developed method for controlling...  相似文献   
734.
Transportation - Transportation vulnerability, defined as lack of access to transportation resulting in financial, social, or health consequences, reduces quality of life. While research has...  相似文献   
735.
Marshall  Wesley E.  Dumbaugh  Eric 《Transportation》2020,47(1):275-314

Conventional transportation practices typically focus on alleviating traffic congestion affecting motorists during peak travel periods. One of the underlying assumptions is that traffic congestion, particularly during these peak periods, is harmful to a region’s economy. This paper seeks to answer a seemingly straightforward question: is the fear of the negative economic effects of traffic congestion justified, or is congestion merely a nuisance with little economic impact? This research analyzed 30 years of data for 89 US metropolitan statistical areas (MSAs) to evaluate the economic impacts of traffic congestion at the regional level. Employing a two-stage, least squares panel regression model, we controlled for endogeneity using instrumental variables and assessed the association between traffic congestion and per capita gross domestic product (GDP) as well as between traffic congestion and job growth for an 11-year time period. We then investigated the relationship between traffic congestion and per capita income for those same 11 years as well as for the thirty-year time period (1982–2011) when traffic congestion data were available. Controlling for the key variables found to be significant in the existing literature, our results suggest that the potential negative impact of traffic congestion on the economy does not deserve the attention it receives. Economic productivity is not significantly negatively impacted by high levels of traffic congestion. In fact, the results suggest a positive association between traffic congestion and per capita GDP as well as between traffic congestion and job growth at the MSA level. There was a statistically insignificant effect on per capita income. There may be valid reasons to continue the fight against congestion, but the idea that congestion will stifle the economy does not appear to be one of them.

  相似文献   
736.
[目的]为提升舰船机舱运维的智能化水平,针对机舱设备种类多、数量大、耦合关系复杂等特点,梳理机舱运维智能化应用的技术路线,开发船岸一体化机舱智能运维系统。[方法]首先,分析国内外机舱智能运维技术的发展趋势,融合利用健康管理、大数据挖掘、数字孪生、数据轻量化传输等技术优势;然后,设计符合舰船机舱特点的一体化智能运维系统。[结果]提出了一种基于数据大脑赋能的机舱智能运维系统功能框架、平台设计、运行体系、运行流程及关键技术应用。[结论]研究成果可为舰船机舱智能运维系统设计及应用实践提供参考。  相似文献   
737.
Port investments are generally analysed one project at a time, often within a set of relevant scenario alternatives. Sometimes the issue consists in assessing a combination of complementary projects at different locations, such as may be the case in addressing the feasibility of comprehensive jetty programmes in inter-island shipping. These alternatives can be evaluated by the so-called 'warehouse approach' of business logistics, as is exemplified in the present exercise.  相似文献   
738.
This study documents that more than a half million tons of radioactive and associated materials, including wastes, were handled at US ports between 1965 and 1984. Although some ports were dominant, radioactive traffic flowed through a large number of ports. An analysis of concordance demonstrates agreement in port rankings over the 20-year period. Large, medium and small ports are identified via a cluster analysis.  相似文献   
739.
In the scope of the European Prometheus project a passenger car with active rear wheel steering was developed by TNO in cooperation with PSA. During development and engineering of the rear wheel steering system simulation tools have been used to reduce development costs. This paper describes the evaluation of different simulation models, from simple to complex, with results of full vehicle driving tests. The optimal balance for model complexity and accuracy was achieved with a 2-dimensional model with an added roll degree of freedom. The results show that validation using time responses can give ambiguous and inaccurate results, and that frequency response functions are much more usable in validation.  相似文献   
740.
Historically there have been only two groups involved in the conflict that has engulfed the US maritime industry for the past fifty years maritime labour unions and shipping companies. The configuration of these groups at different times in this struggle, has led to distinct periods of conflict in the industry. This paper analyses the basis and continuation of the problem.  相似文献   
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