序线性空间中集值优化问题弱有效解的最优性条件

在序线性空间中,引入(u,02;Y+)—广义次似凸集值映射,建立了此映射下的一个择一定理.利用此定理,在序线性空间中获得了带广义不等式约束的集值优化问题弱有效解的最优性必要条件和充分条件.     

序线性空间中集值优化问题弱有效解的最优性条件

在序线性空间中,引入(u,02;Y )—广义次似凸集值映射,建立了此映射下的一个择一定理.利用此定理,在序线性空间中获得了带广义不等式约束的集值优化问题弱有效解的最优性必要条件和充分条件.     

Transport and nation‐state governments: a global review

The review undertaken in this paper shows how, at the beginning of 1988, nation‐states of the world allocated ministerial responsibilities for the important function of transport. A total of 118 countries are examined, compared with 111 in 1982 (Transport Reviews, Vol. 2, No. 4) and 115 in 1985 (Transport Reviews, Vol. 5. No. 1). The analysis reveals an increase in the number of ministers solely responsible for one mode of transport, and notes an increase in the number of designated ministers for tourism. The paper goes on to examine the two main duties of ministers of transport: safety and economic regulation; and of the increasing need for closer international co‐operation as new transport technology, the growing demand for travel and expanding world trade make our world ‘an even more local village’ in the decades to come.     

地质构造和地形对N.Barton岩质评定系数Q值的影响分析

挪威岩土所Barton等人给出的岩质评定系数Q值计算式,从岩体的完整性、结构面发育程度、地下水和地应力的影响等方面,全面地反映了岩体的工程地质状况和水文地质状况,定量地反映了围岩质量的好坏,但对宏观地质构造及地形地貌的影响考虑相对较少.文章通过理论分析和数值计算,提出了三个修正系数,即褶皱影响系数Kfo、断层影响系数Kfa以及地形影响系数Ktf,并针对具体工程给出了相应的取值范围,对Q值进行了修正,反应了工程地质构造、地形地貌对Q值的影响程度,使其表达更为准确.     

工业海洋大气环境下焊接耐候钢Q355NHD腐蚀后力学性能研究

随着钢结构桥梁建设需求不断提高、应用日益广泛,耐候钢以其优良的耐候性能,从材料层面为钢桥防腐提供了一种理想方案;但是,由于中国应用耐候钢的时间较短,耐候钢在某些自然环境下的适用性尚未得到充分论证,对其腐蚀后基本力学性能和疲劳性能的认识尚不完善。为此,以钢桥常用的Q355NHD焊接耐候钢及其对接焊缝为研究对象,针对中国滨海城市常见的工业海洋大气环境,通过周期浸润加速腐蚀试验探讨Q355NHD的耐候性能,并对腐蚀后Q355NHD的单调拉伸性能和疲劳性能开展试验研究。基于形貌观察、基体扫描、锈层分析和腐蚀深度计算等多角度分析,发现在模拟工业海洋大气环境下,Q355NHD尽管会形成具有一定致密性的锈层,但其腐蚀速率等宏观指标相比于普通钢并不突出。腐蚀后单调拉伸试验结果表明:腐蚀8周(等效于青岛受工业污染的海洋大气环境下自然腐蚀20年)后Q355NHD母材试件的屈服强度和抗拉强度分别下降8.1%和7.2%,对接焊缝试件的屈服强度和抗拉强度分别下降14.1%和12.5%。腐蚀后疲劳试验结果表明:腐蚀8周后Q355NHD母材试件和对接焊缝试件的设计疲劳强度分别下降35.6%和30.3%,为317.9 MPa和211.0 MPa,但仍然满足《钢结构设计标准》(GB 50017-2017)中相应构造类别的疲劳设计要求。经与既有文献报道的Q355普通钢试验结果对比,表明尽管Q355NHD在工业海洋大气环境中未表现出良好的耐腐蚀性能,不建议按免涂装使用,但其力学性能在不同批次试验结果中处于较高水平,可以视为一种优质的Q355钢材。     

Cruise activity and pollution: The case of Barcelona

One of the main causes of mortality worldwide is air pollution. To tackle this problem, local, regional and national governments have implemented policies to reduce emissions from industrial and on-road sources. However, when these policies are being designed, shipping emissions are often overlooked. There has been a drastic increase in the demand for cruises and its economic relevance is also growing in port-cities. Barcelona is Europe’s leading cruise port, and it is located near the centre of the city. In this context, this paper analyses the impact of cruise ships in the air quality of the entire city of Barcelona using a dataset with information about pollutants and the number of cruises arriving to the port. We show that there is a direct impact between cruises staying at the port and city pollution. Additionally, the size and age of the cruise also affect air quality. The larger (or newer) the cruise is, the higher the emission generated. Moreover, our simulations show that the whole city is affected by these emissions.     

平均排队长度差最小的单交叉口在线Q学习模型

为改善交叉口排队长度管理,避免交叉口某个方向排队长度过长,采用强化学习理论建立了以平均排队长度差最小为优化目标的在线Q学习模型.针对控制性能指标相对于邻近的配时方案不敏感的特点,提出了以平均排队长度差作为基本单位重新构造奖励函数,目的是拉大各行为对应的Q值差距,提高模型的收敛速度和鲁棒性.集成Excel VBA,Vissim,Matlab建立了在线仿真平台,作为计算环境对算例进行了计算.算例中利用GPS数据对Vissim软件中车辆加减速度曲线进行了标定.计算结果表明以平均排队长度差作为优化目标能够提高各个方向排队长度的平衡性,优化整个交叉口的时空资源;建立的在线Q模型具有学习能力和较快的计算速度,模型能否收敛受到周期取值和可选行为数量的影响.     

卫星定位通信系统中互调干扰的抑制

本文提出了大卫星定位通信系统中采用四相扩频（Ｑ－ＳＳ）技术,并沿用瑞士人给出的卫星转发器功率放大器的数学模型,推导了Ｑ－ＳＳ信号通过卫星转发器后输出的表示式;通过进一步分析发现了采用Ｑ－ＳＳ技术可以在信号解扩后完全消除三阶和五阶的互调干扰。     

高原高寒地区桥梁长期监测技术应用研究

为准确掌握恶劣环境和列车荷载的共同作用下,青藏铁路混凝土桥梁的服役状态和病害发展,同时为类似条件下进行桥梁监测提供借鉴,针对青藏铁路沿线K973石灰沟特大桥的墩梁振动特性和既有病害的发展展开了长期监测。实践证明:现场太阳能供电和GSM/GPRS无线网络传输条件,基本可以支撑监测系统的正常工作;专门研发的现场数据采集分析设备和软件调控平台,能够适应高原高寒地区混凝土桥梁长期监测的需要,系统稳定、数据可靠。监测结果显示,石灰沟特大桥既有桥台前倾的病害发生并稳定后,对相邻梁体及桥墩的工作状态暂无不利影响。     

Local path planning method of the self-propelled model based on reinforcement learning in complex conditions

Conducting hydrodynamic and physical motion simulation tests using a large-scale self-propelled model under actual wave conditions is an important means for researching environmental adaptability of ships. During the navigation test of the self-propelled model, the complex environment including various port facilities, navigation facilities, and the ships nearby must be considered carefully, because in this dense environment the impact of sea waves and winds on the model is particularly significant. In order to improve the security of the self-propelled model, this paper introduces the Q learning based on reinforcement learning combined with chaotic ideas for the model＇s collision avoidance, in order to improve the reliability of the local path planning. Simulation and sea test results show that this algorithm is a better solution for collision avoidance of the self navigation model under the interference of sea winds and waves with good adaptability.