谈如何在预可研阶段做好工程造价控制

工程造价控制是现代工程建设、管理的核心工作之一,要求在现有基础上不断予以完善。本文以预可研阶段工程造价控制作为分析对象,论述该阶段工程造价控制的关键点,再以此为基础,分析预可研阶段的工程造价控制思路,最后从递进关联的角度,就工程造价控制的后续方法进行论述,给出构建精细化作业模式、加强数据挖掘和复用、重点项目的拆分等内容,服务后续工作。     

Innovations and productivity: the shift during the 2008 crisis

This paper investigates how the recent crisis of 2008 changed relations between innovation and firm performance in Western Europe. We apply a structural framework of CDM modelling, which incorporates different stages of the knowledge creation process and takes into account the complex nature of innovations. The study is based on a balanced panel data of 420 listed manufacturing firms from the U.K., Germany and France. All the information is gathered from common sources, thereby reducing subjectivity, a typical problem in the field. We found, the crisis resulted in appreciable changes in the model. The most important evidence is enhancement of the role of firm resources in the post-recession period. We also reveal larger barriers for innovations, increased uncertainty and lower state dependence in R&D engagement, product creation and economic performance. These results could indicate the ‘cleaning effect’ of the crisis, which has worsened the business environment and enhanced competition.     

Do African Economies Grow Similarly?

Abstract

This paper examines economic growth in 52 African countries for 1961–2016 and seeks to find if there is common growth. As all African countries have their particular features, concerning climate, harvest, industry, size, politics, and infrastructure, and more, it seems best to rely on a non-parametric method. Dynamic Time Warping is such a convenient method, also as it allows leads and lags across countries to vary over time, and as it can easily be incorporated into a clustering technique. Five clusters are found, two of which concern Equatorial Guinea and Botswana, and the three other clusters have common growth rates of about 0, 2 and 4 over more than five decades.     

大红山铜矿285中段连续开采中胶结矿柱经济分析

大红山铜矿285中段铜铁合采区原矿品位较低,采用胶结充填体置换矿柱开采可能亏损,矿山未建立胶结充填体置换矿柱开采的利润测算方法。利用285中段铜铁合采区标准矿块测算胶结矿柱开采的直接成本,结合中段建设费用分摊和销售费用,建立胶结矿柱开采的利润测算方法,最终完成285中段胶结矿柱开采的利润测算,为胶结矿柱开采提供指导依据。     

质量和成本约束下CSP-T和Spk集成过程控制方案

多水平连续抽样检验方案(CSP-T)是在线过程质量控制工具，但该方案的第一类风险和第二类风险都较高，且不能满足成本约束。提出了CSP-T和过程良率指数(S_pk)集成过程控制方案，该集成方案在满足质量约束的同时，以最小成本运行，并将两类风险控制在既定水平。建立了极限检验能力下的最优CSP-T方案，依据数据的计数特征驱动质量控制方案运行。基于S_pk估计的精确分布建立了风险控制方案，依据数据的计量特征驱动风险控制方案运行。质量控制方案和风险控制方案是独立互补关系。相比于CSP-T方案，检验工作量没有增加。企业案例验证了集成控制方案的可行性和有效性。     

模糊时间窗约束下的装配线物料配送方案优化

为解决装配线物料无法及时准确配送的问题,提出了一种动态的联合配送策略,在此基础上以最小化单个产品配送成本、最大化工位满意度为目标,建立模糊时间窗约束下的物料配送数学模型。利用NSGA-Ⅱ算法求解出最佳的工位组划分、小车出发时间和配送路径,并对配送小车容量及配送时间窗进行优化。利用Plant Simulation软件搭建某生产线仿真模型进行模拟,验证了配送方案的可行性。与一般配送策略进行对比,结果表明,在保证配送工位满意度的前提下,优化时间窗能进一步降低单个产品的配送成本。     

创新式三工位钢丝圈包布机的研究与设计

截止目前,在市面上常见的对轮胎用钢丝圈进行包布缠绕的设备一般都是采用一台包布机对应一个钢丝圈进行包布缠绕,当需要同时进行多个钢丝圈缠绕时则需要多台包布机,且由于单个包布机之间需要保留一定的安全距离,使得整体所需的工厂占地面积较大;此外,通常情况下是一个操作员操作一台包布机,如果需要多台包布机同时工作则需要多个操作员进行操作,这样会导致生产人力成本上升,且人工操作生产效率较低。     

Life cycle cost of conventional,battery electric,and fuel cell electric vehicles considering traffic and environmental policies in China

Electric vehicles (EVs) are considered a promising alternative to conventional vehicles (CVs) to alleviate the oil crisis and reduce urban air pollution and carbon emissions. Consumers usually focus on the tangible cost when choosing an EV or CV but overlook the time cost for restricting purchase or driving and the environmental cost from gas emissions, falling to have a comprehensive understanding of the economic competitiveness of CVs and EVs. In this study, a life cycle cost model for vehicles is conducted to express traffic and environmental policies in monetary terms, which are called intangible cost and external cost, respectively. Battery electric vehicles (BEVs), fuel cell electric vehicles (FCEVs), and CVs are compared in four first-tier, four new first-tier, and 4 s-tier and below cities in China. The comparison shows that BEVs and FCEVs in most cities are incomparable with CVs in terms of tangible cost. However, the prominent traffic and environmental policies in first-tier cities, especially in Beijing and Shanghai, greatly increase the intangible and external costs of CVs, making consumers more inclined to purchase BEVs and FCEVs. The main policy benefits of BEVs and FCEVs come from three aspects: government subsidies, purchase and driving restrictions, and environmental taxes. With the predictable reduction in government subsidies, traffic and environmental policies present important factors influencing the competitiveness of BEVs and FCEVs. In first-tier cities, BEVs and FCEVs already have a competitive foundation for large-scale promotion. In new first-tier and second-tier and below cities, stricter traffic and environmental policies need to be formulated to offset the negative impact of the reduction in government subsidies on the competitiveness of BEVs and FCEVs. Additionally, a sensitivity analysis reveals that increasing the mileage and reducing fuel prices can significantly improve the competitiveness of BEVs and FCEVs, respectively.     

Herd life,lifetime production,and profitability of Viking Red-sired and Montbéliarde-sired crossbred cows compared with their Holstein herdmates

The first 2 generations from a 3-breed rotation of the Viking Red (VR), Montbéliarde (MO), and Holstein (HO) breeds were compared with their HO herdmates in high-performance commercial herds in Minnesota. The designed study enrolled pure HO females in 2008 to initiate a comparison of 3-breed rotational crossbreds with their HO herdmates. Sires of cows were proven artificial insemination bulls selected for high genetic merit in each of the 3 breeds. The first-generation cows calved for a first time from 2010 to 2014 and had 376 VR × HO and 358 MO × HO crossbreds to compare with their 640 HO herdmates. The second-generation cows calved for a first time from 2012 to 2014 and had 109 VR × MO/HO and 117 MO × VR/HO crossbreds to compare with their 250 HO herdmates. Collection of data ceased on December 31, 2017, and all cows studied had the opportunity for 45 mo in the herd after first calving. Production of milk, fat, and protein (kg) during lifetimes of cows was estimated from test-day observations with best prediction. The lifetime profit function included revenue and cost. Revenue was from production, calves, and slaughter of cull cows. Costs included feed cost during lactation, lactating overhead cost, dry cow cost (including feed cost during dry periods), replacement cost, health treatment cost, insemination cost, fertility hormone cost, pregnancy diagnosis cost, hoof trimming cost, and carcass disposal cost. For individual cows with herd life longer than 45 mo after first calving, survival of cows was projected beyond 45 mo after first calving to estimate herd life, production, and profitability. The 2-breed crossbreds had +158 d longer herd life and the 3-breed crossbreds had +147 d longer herd life compared with their respective HO herdmates. Also, 12.4% of the 2-breed crossbreds died up to 45 mo after first calving compared with 16.3% of their HO herdmates. Furthermore, approximately 29% of both the 2-breed and 3-breed crossbreds lived beyond 45 mo after first calving compared with approximately 18% of their respective HO herdmates. On a lifetime basis, the 2-breed and 3-breed crossbreds provided +$122 and +$134, respectively, more cull cow revenue compared with their HO herdmates. For lifetime replacement cost, the 2-breed crossbreds did not differ from their HO herdmates; however, the 3-breed crossbreds had ?$28 less lifetime replacement cost compared with their HO herdmates because of their younger age at first calving. The combined 2-breed crossbreds had +$0.473 (+13%) more daily profit (ignoring potential differences for feed efficiency) and the combined 3-breed crossbreds had +$0.342 (+9%) more daily profit compared with their respective HO herdmates. This resulted in +$173 more profit/cow annually for the combined 2-breed crossbreds and +$125 more profit/cow annually for the combined 3-breed crossbreds compared with their respective HO herdmates.