工作流模型时间与费用性能评估算法

对无环工作流模型的时间与费用性能参数进行分析,通过引入循环结构的提取算法,实现对有环工作流模型的时间与费用性能评估.利用改进的Tarjan算法和七元组来提取和存储每一个循环结构的参数信息.分析所有的七元组,计算所有标志节点的进度与费用值.有环结构中的循环结构在被提取完之后,会转化为无环结构,利用无环模型的算法即可进行进度与费用的评估.实验证明:算法能很有效地评估复杂模型的进度与费用性能,算法执行效率高,计算结果准确.

性能费用比法在沥青路面基层类型选择中的应用

传统的沥青路面基层类型选择方法(层次分析法和模糊综合评判方法),其准确性在很大程度上依赖于专家的判断,使得方案评判的可信度较低。借鉴路面管理系统、寿命周期费用等研究成果,提出了一种新的选择方法——性能费用比法。本文给出了该方法的定义、详细使用步骤和算例。结果表明,性能费用比法概念明确,评判结果完全定量化,是进行多方案比选的有效方法。随着我国路面管理系统研究的深入,这种方法将得到日益广泛的使用。

多接口移动主机最优化费用和性能方法研究

目前移动主机普遍具有多个网络接口,可以由这些接口通过不同的网络服务提供商(ISP)接入到Internet中.因此,移动主机与Internet之间就可能存在多条路径,通信的费用和性能取决于ISP的收费策略和网络通信性能.文中首先对移动主机与Internet通信进行建模,然后提出一种基于主动探测可用路径的最优化费用和性能的流量分配方法.最后,对此方法进行仿真,并与几种常见流量分配方法进行对比.结果表明本文所提出的方法能根据主机对费用和性能的需求合理分配和控制流量.

卫星地面站费用／性能评估

在轨或计划中的近地轨道科学卫星、地球资源卫星和全球通信卫星数据的迅速增长，要求一种大大降低地面测控费用的方法。从经济上考虑，为每个近地轨道卫星建立单一、专用的卫星测量站已不再可行。为了拓展商业空间市场，需要一种新的方法来降低近地轨道卫星数据业务的费用。本文论述了近地轨道测控所需的性能，提出一种独特的、创新的办法提供测控服务和有效载荷服务。

基于性能费用比的高速公路沥青路面基层选型

在一定的交通、环境和经济条件下,为了合理有效地进行高速公路沥青路面基层类型的选择,综合考虑路面结构、材料、使用性能和路面费用,提出了性能费用比法,并进行了实例分析。研究结果表明该性能费用比法能够有效的用于高速公路沥青路面的基层选型。

以费用为独立变量的武器型号论证技术

以费用为独立变量的定量决策技术包括:建立系统性能-费用模型并对其权衡。系统建模通过建立关键性能指标、效能和费用三者间的关系,找到最佳平衡点。完成效能与费用关系权衡后,总拥有费用则已确定,即可确定型号系统在寿命周期各阶段非所需的费用目标,同时再考虑非关键性能指标的影响。

3种路面方案选择方法的对比应用

在进行路面方案选择时,常采用层次分析法和模糊综合评判方法,评判结果依赖于专家的判断,方案评判的可信度较低。借鉴路面管理系统、寿命周期费用等研究成果,提出了一种新的选型方法———性能费用比法,给出了详细的使用步骤,并结合实例进行了3种选型方法的对比。结果表明,性能费用比法不仅具有专家评判的优点,而且评判结果更合理全面,完全定量化,是进行路面方案选择的有效方法,将得到日益广泛的使用。

长大纵坡段沥青路面结构研究

针对长大纵坡沥青路面破坏的特点,结合长寿命路面的设计方法及依托工程的具体情况,研究适合于长大纵坡路段的沥青路面结构,并从其费用及性能方面同常用的沥青混凝土路面结构进行比较。结果表明,本项目采用的结构虽在初建费用上略高于普通的沥青路面,但后期的养护费用及用户费用远小于普通沥青路面,且其路用性能也优于普通的沥青路面,综合其各方面的特点,认为本结构适用于长大纵坡段。

一种新的沥青路面基层类型选择方法及应用

传统的沥青路面基层类型选择方法(层次分析法和模糊综合评判方法),其准确性在很大程度上依赖于专家的判断,使得方案评判的可信度较低。借鉴路面管理系统、寿命周期费用等研究成果,提出了一种新的选择方法——性能费用比法。给出了该方法的定义、详细使用步骤和算例。结果表明:性能费用比法概念明确,评判结果完全定量化,是进行多方案比选的有效方法。随着中国路面管理系统研究的深入,这种方法将得到日益广泛的使用。

基于性能-费用模型的厂拌再生沥青混合料优化设计

为了克服厂拌热再生沥青路面水稳定性不足的风险,以水稳定为控制指标,在性能-费用模型的基础上优化其材料设计。首先,采用响应面法建立了沥青混合料回收料掺量、沥青含量、矿料级配与水稳定性的二次回归模型,构建了厂拌热再生施工全过程的生产施工费用模型,提出了基于性能-费用的再生沥青混合料材料优化设计模型。然后,结合遗传算法、线性综合评价方法,求取了优化的材料设计参数。结果表明:响应面法可以有效解决多因素影响规律的建模分析问题;沥青混合料回收料掺量、沥青含量、矿料级配对再生沥青混合料的水稳定性具有显著影响;以福银高速三明段为算例,相同水稳定性控制目标下的优化后费用较实际降低了26.7%,优化后的材料参数如下:沥青混合料回收料掺量为51%、沥青含量为4.61%、级配参数为0.445。

涡桨发动机方案阶段经济可承受性分析

基于涡桨发动机经济可承受指标的定义,建立了涡桨发动机方案阶段的技术指标体系,提出了涡桨发动机全寿命周期费用指标及估算方法。给出了涡桨发动机方案阶段性能/费用权衡分析、全寿命周期费用估算及经济可承受性指标分析的过程,并以同一涡桨发动机为基准,对比分析了单转子方案和双转子方案的经济可承受性,最终得出该型发动机双转子方案经济可承受性更优的结论。

Comparative analysis of perpetual pavement structures based on pavement performance and life cycle cost

Pavement performance and economic efficiency are researched on the perpetual test pavement of Yijiang-Suzhou Express Highway in Jiangsu province, China. Test sections were continuously monitored. The conditions and developing laws of deflection, rutting and cracking are compared among the perpetual pavement with the rich binder layer （RBL）, the perpetual pavement without the RBL, and the conventional semi-rigid asphalt pavement in the past eight years after opening for traffic. Economical evaluation is conducted via life cycle cost analysis （LCCA）. Based on the performance comparison and LCCA analysis, sections with the RBL have good crack resistance, but they are not very satisfactory in the aspect of permanent deformation; the conventional semi-rigid asphalt pavement is the least economic one due to requiring more frequent maintenance. Research results show that the perpetual pavement without RBL is a more appropriate structure for the test site.

COST:Coding over Spatial-Temporal Diversity for Low-Duty-Cycle WSNs

In low-duty-cycle wireless sensor networks,designers have to cope with unreliable links and limited communication capacity.In this work,we propose COST,a coding scheme that leverages spatial-temporal diversity to achieve higher energy efficiency and lower delay of packet transmissions.We particularly address long sleeping intervals in low-duty-cycle networks by exploiting multi-path diversity.Specifically,we propose to employ an erasure-coding scheme to improve reliability.With respect to energy efficiency and delivery timeliness,we formulate the problem in optimal allocation of coded blocks over multiple paths,which is then proved to be NP-hard.We further propose a near-optimal algorithm to solve the allocation problem.Through extensive simulations,we evaluate the impact of network parameters and demonstrate the effectiveness of our proposal.

Effect of Inorganic and Organic Based Fertilizers on Growth Performance of Tea and Cost Implications in Kusuku, Nigeria

A plot of 24 m × 10 m under fallow management after several years of cultivation to maize （Zea mays） was planted to tea （Camellia sinensis） cuttings at 1.0 m ×0.6 m and treated with or without fertilizer. The tea cuttings were applied NPK 25：5：5 （reference fertilizer）, cocoa husk, cow-dung, tea fluff and poultry droppings as manures, mixtures of the manures with urea in 3：1 ratio of N contents as organomineral and the control （no fertilizer）, monitored for growth performance for two years at Kusuku （6°50＇N; 11 °07＇E）, Nigeria. The organic based fertilizers generally outperformed NPK 25：5：5 and control in all the growth parameters. Organominerals resulted in an overall higher plant height, girth, number of leaves and branches compared to the manures in the first year of establishment, while the values were higher for manure treated plants in the second year. This trend was attributed to quicker release of nutrient by the organominerals in the first year, while the manures had undergone adequate decomposition for sufficient nutrient release to the advantage of the tea plants in the second year. However, comparative cost analysis showed that organominerals were more economical to achieve optimum tea production at minimum cost in the locality.

A Study of Different Unwarping Methods for Omnidirectional Imaging

Omni-directional imaging system is becoming more and more common in reducing the maintenance fees and the number of cameras used as well as increasing the angle of view in a single camera. Due to omni-directional images are not directly understandable, an approach namely the un-warping process, has been implemented in converting the omni-directional image to a panoramic image, making it understandable. There are different kinds of methods used for the implementation of this approach. This paper evaluates the performance of the 3 universal un-warping methods currently applied actively around the world in transforming omni-directional image to panoramic image, namely the pano-mapping table method, discrete geometry method （DGT） and the log-polar mapping method. The algorithm of these methods will first be proposed, and the code will then be generated and be tested on several different omni-directional images. The images converted will then be compared among each other and be evaluated based on their performance on the resolutions, quality, algorithm used, complexity based on Big-O computations, processing time, and finally their data compression rate available for each of the methods. The most preferable un-warping method will then be concluded, taking into considerations all these factors.

Performance analysis of a solar-aided power generation(SAPG) plant using specific consumption theory

In contrast to a traditional coal-fired power generation plant where steam extracted from a turbine is used to preheat the feedwater in all preheating stages, a solar-aided power generation(SAPG) plant uses solar heat to replace a part or all of the extracted steam in one or more preheating stages. The performance of an SAPG plant with different replacements is investigated in this study by using specific consumption theory(SCT). Fuel-specific and cost-specific consumption models for SAPG plants are built based on the SCT. A typical 330 MW coal-fired power plant is used as the study case. The performance of the SAPG plant in terms of specific consumption, with steam obtained from the first through the eighth(except for the fourth) stages of extraction replaced by solar heat, is compared with that of the reference coal-fired power plant. The fuel-specific consumption of the SAPG plant is determined to be lower than that of the reference coal-fired power plant. The fuel-specific consumption accrual distribution in SAPG plants is used to assess the effect of each individual replacement. Effective strategies to reduce the specific costs of the SAPG and coal-fired power plants are proposed based on the results of this study.