从限额设计谈投资控制

文章根据设计阶段投资控制的现状及存在问题,提出只有在设计行业全面推行限额设计,深化设计阶段的投资控制工作,才能从根本上体现全过程投资控制的理念,提高投资控制效果,节约建设工程总投资。     

Solar radiation climate in Malawi

Recently, Diabaté et al. [Diabaté, L., Blanc, Ph., Wald, L., 2004. Solar climate in Africa. Solar Energy 76, 733–744] created a map of solar radiation climate in Africa using clearness index for 62 sites. They established a solar climate class II located in Malawi and Madagascar. However, their analysis did not include any irradiation data from a site in Malawi. In this study, the solar radiation climate of Malawi has been studied using long-term global radiation data from a local site. The mean monthly (K_tm) and seasonal (K_ts) daily clearness indices for the site were computed. It is observed that K_tm has two maxima in a year (K_tm = 0.58 in May and K_tm = 0.64 in September), in close conformity with findings of Diabaté et al. (2004). Other results are presented and discussed.     

Adsorption and decomposition of H2S on Pd(1 1 1) surface: a first-principles study

Gradient-corrected density functional theory was used to investigate the adsorption of H₂S on Pd(1 1 1) surface. Molecular adsorption was found to be stable with H₂S binding preferentially at top sites. In addition, the adsorption of other S moieties (SH and S) was investigated. SH and S were found to be preferentially bind at the bridge and fcc sites, respectively. The reaction pathways and energy profiles for H₂S decomposition giving rise to adsorbed S and H were determined. Both H₂S_(ad) → SH_(ad) + H_(ad) and SH_(ad) → S_(ad) + H_(ad) reactions were found to have low barriers and high exothermicities. This reveals that the decomposition of H₂S on Pd(1 1 1) surface is a facile process.     

单源点法的一种改进

在应用能量线性叠加计算港内不规则波绕射系数时^[1,2]，通过假设不同的计算点具有不同的方向谱，从而增加单源点法考虑地形变化的能力。其中各计算点的方向谱由逆波向线追踪方向确定。本文由此观点建立数学模型。并通过实例计算。来验证这个想法。     

铀工业指标研究的几个问题

本文介绍在铀矿床工业指标制定中,对未来矿山开采设计方案及经济计算参数几千问题的分析,以利于合理的制定铀矿床工业指标,为铀矿冶企业技术改造,在建企业修改设计和为选择新建企业提供决策依据,进而使铀矿冶企业提高经济效益。     

Ti 离子注入 LiNbO_3表面光学性能

本文研究了 x,y,z 三种切向的 LiNbO_3单晶片注入350keV 高能 Ti 离子(注入剂量为1.5×10~(17)/cm~2)后的表面光学性能。利用光谱仪及 AUEL 椭偏仪对三种切向 LiNbO_3试样在不同工艺处理后的光透射率及折射率进行了测试。注入损伤造成的光损耗可通过热处理消除,使晶格结构恢复至与完整晶格排列相近;注入层的折射率可增加11—13％左右。     

UL简介与CCL认可

本文从六个方面对UL的基本知识作了一个简要的概述及CCL认可过程的介绍,希望能为业界同仁提供一个参考方向。     

基于过程能力指数的刀具寿命研究

利用Glejser检验方法拟舍出刀具磨损过程残差模型，在此基础上，计算换刀时刻的过程能力指数，并且根据企业所要求的最低过程能力指数，计算刀具的质量寿命，提出将刀具的切削寿命和质量寿命结合起来进行换刀决策的方法。     

Crack Development in Individually Quick Frozen Cut and Peel Carrots

ABSTRACT:  Crack development during freezing (CDF) is one of the major challenges in individually quick frozen (IQF) cut and peel carrot processing. The effects of processing and freezer storage on crack development were examined on the cut and peel carrot variety, Sugarsnax. Carrot samples were removed from the major processing steps, the trans-slicer, the shaper, the blancher, and the dryer, and examined for crack development by measuring percentage cracked, crack morphology, total soluble solids, moisture levels, and membrane injury index immediately after processing. These parameters were also examined following 20 wk of standard freezer storage for cut and peels. Approximately 2% of nonprocessed carrots were cracked compared to 45% of carrots after the initial trans-slicing stage. As the processing continued, cracking decreased due to the removal of the outer epidermis to 16% of the finished product. This suggests that CDF was initiated at the 1st processing stage. Crack width and depth were 2.3 and 2.6 mm, respectively, at the trans-slicer stage and decreased to 1.1 and 1.8 mm at the end of the line. It was found that CDF was further exacerbated by freezer storage due to inefficient water removal at the dryer stage. Crack width and depth increased to 1.5 and 3.0 mm after 20 wk for freezer storage. Root size also played a role in CDF, suggesting that larger pieces are more susceptible to crack development. Total soluble solid concentrations did not play a role in crack formation during cut and peel processing.     

Index of critical points in rational l-approximation

This article is concerned with the l²-approximation of a given transfer function f by a rational one whose order is prescribed. We show that the sum of the indices of the critical points of the criterion is generically equal to 1, and in particular does not depend on f.