施工工程成本控制分析与实践

控制工程成本在国内项目和国际工程中都占有极为可观的地位,它不仅仅牵扯到工程造价,还极为关键地影响着整个工程是否合理合适正常的开展,乃至后期的收尾工程。当然,在工程所有经济条款中都有所涵盖,实际工程进程之中,也是处处防范超标作业。     

乌金峡水电站灯泡贯流机组初期运行问题分析

乌金峡水电站灯泡贯流式机组投运初期,因设计、制造、安装等诸多原因导致机组故障率较高,经过2 a多来的消缺、技改,机组运行可靠性、稳定性逐步提高,逐步取得了一定的效果。文章针对具体问题产生原因及相关改进措施予以阐述,并进行相关优化分析探讨。     

某单机无穷大电力系统暂态稳定性分析仿真

电力系统是一个复杂的动态系统,系统一旦出现稳定性问题,可能会在较短的时间内发生严重后果,因此,在电力系统规划、设计、运行等工作中都要进行大量的暂态稳定分析。介绍了电力系统时域仿真数学模型,构建了单机无穷大系统仿真模型。仿真结果表明:故障切除时间越短,发电机阻尼越大,系统越容易稳定,且在单相短路接地故障情况下系统最容易稳定。     

引水工程运行管理决策支持系统设计与实现

引水工程是我国水资源战略调配的重要举措,在我国水资源调配已经或将发挥重要作用,引水工程的信息化建设将促进和提高引水工程运行管理水平。在分析引水工程特点及其运行管理需求的基础上,应用先进的信息采集、通信网络、空间和计算机控制处理技术,对引水工程运行调度管理决策支持系统进行分析设计,以吉林省引嫩入白引水工程为例,进行应用实践。通过应用表明,该系统运行稳定,界面友好,提升了引水工程水利信息化水平,充分发挥了引水工程的效益。     

Acoustic evaluation and adjustment of an open-plan office through architectural design and noise control

Arranging office space into a single open room offers advantages in terms of easy exchange of information and interaction among coworkers, but reduces privacy and acoustic comfort. Thus, the purpose of this work was to evaluate the acoustic quality of a real open-plan office and to propose changes in the room to improve the acoustic conditioning of this office. The computational model of the office under study was calibrated based on RT and STI measurements. Predictions were made of the RT and STI, which generated the radius of distraction r(D), and the rate of spatial decay of sound pressure levels per distance doubling DL(2) in the real conditions of the office and after modifications of the room. The insertion of dividers between work stations and an increase in the ceiling's sound absorption improved the acoustic conditions in the office under study.     

Capture of shrinking targets

‘Shrinking targets’ are targets whose size diminishes with time. The task studied is a modification of Fitts' (1954 Fitts, P. M. 1954. The information capacity of the human motor system in controlling the amplitude of movement. Journal of Experimental Psychology, 67(6): 381–391. [Crossref] , [Google Scholar]) paradigm, with the difference that, as soon as the movement is started, the target size reduces at a constant rate until it finally vanishes. Very little research has been reported on this problem apart from Johnson and Hart (1987 Johnson, W. W. and Hart, S. G. Step tracking shrinking targets. Proceedings of the Human Factors Society 31st annual meeting. October1987, New York City. pp.248–252. Santa Monica, CA: HFES.  [Google Scholar]) and Hancock and Caird (1993 Hancock, P. A. and Caird, J. K. 1993. Experimental evaluation of a model of mental workload. Human Factors, 35(3): 413–429. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). Two experiments are reported aimed at determining the parameters that affect the movement time and the probability of capturing a target when there are different amplitudes of movement, target widths and shrink rates. A multiplicative model is required to describe movement time data, which is dependent on Fitts' Index of Difficulty, the shrink rate and the product of these two variables. An alternative model describes the critical movement time, for a specified probability of target capture, in a modified form of Fitts' Law.

Statement of Relevance: Modifications of Fitts' Law have been developed for many different movement tasks. Shrinking targets occur in circumstances such as gunnery and in computer games, where a target is moving away from the person. An expression is developed for the critical time to capture the target in terms of a modified form of Fitts' Law.     

A new radial basis functions method for pricing American options under Merton's jump-diffusion model

A new radial basis functions (RBFs) algorithm for pricing financial options under Merton's jump-diffusion model is described. The method is based on a differential quadrature approach, that allows the implementation of the boundary conditions in an efficient way. The semi-discrete equations obtained after approximation of the spatial derivatives, using RBFs based on differential quadrature are solved, using an exponential time integration scheme and we provide several numerical tests which show the superiority of this method over the popular Crank–Nicolson method. Various numerical results for the pricing of European, American and barrier options are given to illustrate the efficiency and accuracy of this new algorithm. We also show that the option Greeks such as the Delta and Gamma sensitivity measures are efficiently computed to high accuracy.     

Third-order temporal discrete scheme for the non-stationary Navier–Stokes equations

In this article, we suggest a new third-order time discrete scheme for the two-dimensional non-stationary Navier–Stokes equations. After presenting the Galerkin finite element approximation for the spatial discretization, we consider an implicit/explicit time discrete scheme for the problem, which is based on the two-step Adams–Moulton scheme (implicit scheme) for the linear term and the three-step Adams–Bashforth scheme (explicit scheme) for the nonlinear term. In this method, we only need to solve a linearized discrete system at each time step, so the scheme can converge fast and the computational cost can be reduced. Moreover, under some assumptions, we deduce the stability and optimal error estimate for the velocity in L ²-norm.     

Research on Ant Colony Algorithm in Vehicle Operation Adjustment Based on IOT

Automatic solution of vehicle operation adjustment is the important content in realizing vehicle traffic command automation on Internet of Things platform. Based on both the organization realization of Internet of Things platform and the merging vehicle operation adjustment into the Flow-Shop scheduling problem in manufacturing systems, this paper has constructed the optimization model with a two-lane vehicle operation adjustment. With respect to the large model solution space and complex constraints, a better solution algorithm is proposed based on ant colony algorithm for optimal quick solution. The simulation results show that the algorithm is feasible and the approximate optimal solution can be quickly obtained.     

Two-echelon inventory model with service level constraint and controllable lead time sensitive to order quantity

The decision-making and optimization of two-echelon inventory coordination were analyzed with service level constraint and controllable lead time sensitive to order quantity. First, the basic model of this problem was established and based on relevant analysis, the original model could be transformed by minimax method. Then, the optimal order quantity and production quantity influenced by service level constraint were analyzed and the boundary of optimal order quantity and production quantity was given. According to this boundary, the effective method and tactics were put forward to solve the transformed model. In case analysis, the optimal expected total cost of two-echelon inventory can be obtained and it was analyzed how service level constraint and safety factor influence the optimal expected total cost of two-echelon inventory. The results show that the optimal expected total cost of two-echelon inventory is constrained by the higher constraint between service level constraint and safety factor.