谈混凝土路面施工质量的监控

农村公路的改扩建在我国正在积极实施,如何合理有效地改扩建还没有成熟的经验可循,其中如何对农村公路混凝土路面现有路况进行方便快捷且行之有效的检测,为设计施工提供有效的基础数据,成为一个值得深入研究的问题。具体探讨了农村公路混凝土路面改扩建施工质量的监控与检测技术发展。     

交通信号控制参数的仿真优化方法研究

为优化区域交通网络中各信号控制器的配时方案,利用递推最小二乘算法(RLS)和同时扰动随机近似(SPSA)算法,由检测器流量估计DynaCHINA动态网络交通仿真与分析系统的动态OD矩阵,输入并标定各路段的速度-密度模型参数和饱和流量,获得网络状态的准确估计,包括各路段的速度、密度、流量、队列长度等;在此基础上,利用SPSA算法优化各信号控制器配时参数,包括各信号控制器的周期、相位差和绿信比,使得网络中车辆的平均旅行延误、队列长度、或交叉口通过量等指标最优. 针对实际路网的测试表明,本文的参数标定方法可以获得准确的检测器流量估计,结果明显优于Ashok K的动态OD矩阵与检测器流量估计方法;与现有的基于Synchro信号配时优化软件获得的结果相比较,该方法可较大幅度缩短车辆在路网中的平均旅行延误,并可推广应用于更复杂的区域路网的信号控制参数优化等场合.     

Impact arresting process mechanical modeling and sliding model buffer control based on magneto-rheological fluid

The research on the form and control method of impact load arresting buffer has been an active topic in the field of buffer arresting system (BAS). It becomes significant on reducing the weight of arresting system, improving the hindered efficiency, and guaranteeing the security of BAS. The hydraulic hindered device of impact load is currently used in BAS. There are some problems. For example, the system needs large power sources. However, once the power of active hydraulic control system is turned off, there arise unpredictable security risks. An arresting form of semi-active control based on magneto-rheological damper (MRD) is proposed, and the mechanical model of the BAS is established. Meanwhile, the state equation of impact load BAS is established according to the characteristics of impact load buffer arresting, and its sliding model buffer control is achieved. Due to the chattering characteristic of the output signal of sliding mode controller, the method to prevent chattering is designed based on short-term energy and zero-crossing rate detection. For the model and chattering suppression of sliding model buffer control algorithms, simulation results show that the proposed state equation and the arresting model are reasonable, and the design of semi-active control algorithm is effective. On the condition of the buffer control system requirement and the accuracy, the proposed algorithms effectively control the chattering of sliding mode control algorithms, and improve the security of the BAS.     

犬胰腺左叶缺血模型的建立及意义

目的 建立犬胰腺左叶的缺血模型并探讨其意义。方法 解剖犬胰腺,结扎脾动脉近心端,建立犬胰腺左叶的缺血模型,观察术后病理生理、病理变化及并发症的发生情况。结果 实验用12条犬术后存活良好,无严重并发症发生,缺血部位胰腺组织坏死,并被纤维组织修复。结论 犬胰腺体尾部模型容易建立,安全、可靠,对人体晚期胰腺癌的治疗具有指导意义。     

本田汽车公司重新崛起之路

本田公司８０年代曾经成为日本汽车业成功的典范，９０年代初开始陷入困境。１９９６年，本田公司对自己的经营方针进行调整，将经营模式从生产公司向制造商和大型营销商转变。该公司大力改革，树立以客户为本的经营思想，对市场变化迅速作出反应。其推出的４种休闲型汽车，均已成为日本国内最畅销的汽车。目前，本田公司又把其开拓重点转向北美市场，在北美地区的生产能力已达８４万辆。