国外公路工程的人工费计算

本文从国外实际施工发生的人工费出发,讨论了国外人工费与项目管理水平的关系。文中举例说明从实际施工角度如何对一个国外项目的人工进行配备,根据国内定额的含义,计算出了这个项目的综合人工工日总计人工费。     

Effect of days to conception in the previous lactation on the risk of death and live culling around calving

The objective was to quantify the effect of days to conception (days open) in the previous parity on the risk of death and live culling (excluding the disposal reasons “dairy purposes” and “death”) in the proximity of a subsequent calving in Holstein cows enrolled in the Dairy Herd Improvement program. After edits, 2,075,834 observations of cows calving between 2001 and 2007 in herds located in 36 US states primarily east of the Mississippi river were available. The period at risk included the time between 14 d before expected calving to 60 d after calving. Days open were categorized in 6 periods: 0 to 45 d, 46 to 90 d, 91 to 150 d, 151 to 210 d, 211 to 300 d, and 301 to 600 d after calving in the previous parity. Other variables of interest included parity, length of the dry period before calving, relative last test-day milk yield before dry off before calving, season of calving, and the cow's relative 305-d mature equivalent (305ME) milk yield before calving. Control variables were calving year, herd size, and relative herd 305ME milk yield. All variables were categorized. Generalized mixed models were used and included herd as random effect. Interactions between days open and the variables of interest were included in the models. Least squares means for the risk of death between −14 and 60 d after calving were 2.5, 2.5, 2.9, 3.6, 4.4, and 5.8% for increasing categories of days open. Similarly, for the same categories, least squares means for the risk of live culling were 4.5, 5.0, 5.4, 6.1, 6.9, and 8.1%. The effect of days open on the risk of death was slightly greater for third-parity cows, for long dry periods, for cows with low test-day milk yield before dry off before calving, for spring calvings, and for intermediate relative 305ME milk yield before calving. Similar trends for these interactions were found for the risk of live culling, except for relative 305ME milk yield before calving, where the effect of days open was more pronounced for high-producing cows. In conclusion, increased days open in the previous parity were associated with a greater risk of death and live culling around calving.     

沼泽沉积环境的辫状河道特征及其识别方法

鄂尔多斯盆地二叠系石盒子组盒8砂岩岩性气藏属沼泽背景下的辫状河沉积。砂岩以粗砂岩、中粗砂岩和中砂岩为主。层理类型主要为块状层理、板状交错层理。沉积序列总体上呈下粗上细的正旋回。心滩沉积微相是最主要的有效储层沉积单元，其内部结构较均匀，伽马曲线表现为较平滑的低值箱状曲线特征。河道地震反射外形呈透镜状或顶平下凸的丘状，属差连续性、中振幅、上超充填地震相。在开发前期井少且井距大的情况下，综合应用地震、地质，测井、钻井等资料，利用地震波形聚类分析和古构造恢复方法进行河道识别，得到盒8期辫状河道平面分布特征。据此优选建产区块和部署开发井位，取得了较好效果。     

浅述古今玉雕工艺流程与技法

简要介绍了古今玉雕加工工艺中的加工设备、加工工具、研磨材料的演变和发展。同时介绍了现代玉器加工从选料、设计、制作到抛光的全部工艺流程以及不同时代的工艺技法。     

Methodology for estimation of days dry effects

The primary objective of this research was to determine if, with appropriate methodology, unbiased estimates of days dry (DD) effects on subsequent lactation milk yield can be obtained from field data, particularly when DD is correlated with cow effects. Another objective was to ascertain relevant sampling properties of designed trials for estimation of DD effects. Simulated records were used to assess methodology. Along with a model with no adjustments for cow effects, alternative models including 1) previous lactation milk yield, 2) a prior adjustment for cow effects estimated from an animal model, and 3) a combination of 1 and 2, were tested.Estimates from the unadjusted model were biased downward; however, the 3 alternative analyses provided estimates of DD effects that were essentially unbiased, with a prior adjustment for cow effects and previous milk yield in the model providing the best results in terms of elimination of bias. Therefore, DD effects can be estimated from field data without bias from cow effects.A designed trial with 2 groups and 10 or fewer cows/ group is noninformative and has an unacceptably high probability of leading to invalid conclusions. A minimum of 30 cows/group is considerably better and should be used whenever possible. Even with 30 cows/group, however, the power is low unless the difference between DD groups for yield is at least 1130 kg. Prior correction of 305-d, mature equivalent records for cow effects, using predicted producing abilities, could be done in designed trials to improve the statistical power of tests and accuracy of estimates.     

雨季生产润滑油水分不合格原因探讨

水分是润滑油的一项重要指标。润滑油在雨季生产过程中,因连续降雨和环境湿度大,容易造成润滑油水分不合格,文章从人、机、料、法、环等方面进行分析,通过分析发现,基础油储存时间长、半罐调合生产是润滑油雨季生产水分不合格的主要原因,通过控制基础油库存、满罐调合及过程防护,可以减少雨季生产润滑油水分不合格,降低质量风险。     

年预计雷击次数的精确计算

针对防雷设计中年预计雷击次数计算结果偏大的问题,结合实际工程项目,介绍用CAD作图法计算建筑物截收相同雷击次数的等效面积的方法,以使年预计雷击次数计算结果更合理,更贴近实际工程防雷需求。     

Genetic components of days open under heat stress

A reaction norm approach was used to estimate the genetic parameters of days open (DO) with a model that accounted for heat stress. Data included DO records for Georgia, Tennessee, and North Carolina in the Southeastern United States. A fixed effect model included herd-year, month of calving (MOC), age of cow, and a regression on 305-d milk yield. The reaction norm model additionally included the effect of animal with random regression on a heat stress index (HI), calculated as the standardized solutions to MOC derived from the fixed effect model; the residual variance was assumed to be a function of the HI. The shape of the distribution of the HI was close to a sinusoidal function with the highest value in March/April and the lowest value in September. Genetic and residual variances and heritabilities were highest for spring calvings and lowest for fall calvings. The variance associated with the random regression of the highest level of HI was 33% of the genetic variance of the regular animal genetic effect. Genetic correlation between these effects was 0.67. As a validation, DO data were grouped into 4 seasons of calving and treated as different traits. A 4-trait mixed linear model that included the fixed effects listed above except MOC, was used to analyze the grouped data. In general, the estimates of genetic and residual variances of the multiple trait analyses followed those of the reaction norm model. Genetic correlations of spring with summer, and fall with winter were both 0.90. Genetic correlations between spring/summer and fall/winter were around 0.80. The reaction norm model for DO allows inexpensive genetic evaluation of fertility under heat stress. Results of such an evaluation may strongly depend on editing criteria and model specifications.     

短期负荷预测中考虑积温效应的温度修正模型研究

由于夏季负荷受温度因素影响较大,持续高温天气会造成积温效应,导致负荷出现一定程度的非常规增长,传统的短期负荷预测方法难以满足实际需求。因此,为了反映积温效应的影响程度,本文提出了温度修正模型,通过拟合温升曲线、求解负荷温度弹性系数来确定高温日的界限温度,同时给出了利用相关系数求解最大累计天数和累积效应系数的方法。算例分析表明,所提出的方法能够准确地反映积温效应的影响,提高短期负荷预测的精度。     

数据挖掘与非正常日的负荷预测

提高非正常日的负荷预测精度是当前负荷预测工作的难点。文中提出了一种基于知识库的事先判别突变并做出适当处理的预测流程,介绍了利用数据挖掘的决策树技术建立知识库的方法,并给出了几种典型的非正常日修正模型。最后,通过对长时期负荷预测数据的统计分析,说明了新方法的有效性和实用性。