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991.
为满足产品装配的需要,PCB半孔设计应运而生,文章介绍了多种加工工艺半孔的实际过程,在不同加工条件下对于不同的工艺要求对我们传统的工艺流程进行相应的调整、解决所有工艺方面存在的难点,有效的提高制程加工能力,达到批量生产目的,对工序的实现过程做大量的可行性试验和需要注意的细节要素控制,最终完成半孔的加工。 相似文献
992.
Frank A. Btzkes 《Bautechnik》2010,87(3):145-157
Der Nachweis des gestörten Bauablaufs ist die schwierigste Herausforderung für Baubetriebler. Dies liegt nicht nur an der Komplexität gestörter Bauabläufe großer Projekte, sondern vor allem an den Anforderungen, die Baujuristen an den Nachweis stellen. Disturbed construction process — Determination of extra construction time and calculation of the additional costs of construction. The detection of the disturbed construction process is the most difficult challenge for construction managers. This is not only because of the complexity of disturbed construction processes of large projects, but primarily because of the requirements of demonstration for the legal experts in construction. 相似文献
993.
深网数据源的动态性、自治性和体量使第三方应用难以完全爬取所有Web数据.文中研究查询类型(仅允许Top-k查询)和查询资源约束下深网数据源爬取问题,提出基于Top-k查询约束的深网增量爬取方法,结合历史数据和领域知识,优化总体数据质量.首先基于查询树获得有效查询,利用历史数据和领域知识估计查询变化和查询代价.然后,基于估计的查询代价和数据质量,近似选择最优的查询子集最大化总体数据质量.实验表明文中方法较好地提高动态Web数据库爬取的效率和数据质量. 相似文献
994.
Thao M Ho Tony Howes Bhesh R. Bhandari 《International Journal of Dairy Technology》2016,69(3):313-327
Under typical refrigeration conditions (4–7 °C), unopened fresh cottage cheese only lasts for approximately 3 weeks unless preservatives are added. The spoilage of cottage cheese during storage is primarily due to the growth of Gram‐negative psychrotrophic bacteria, yeasts and moulds. To extend its shelf‐life, along with a strict sanitation practice throughout the manufacturing process, an appropriate preservation approach is generally applied. Many methods to preserve cottage cheese have been reported. These can be classified into three categories, namely food‐grade chemicals, heat treatment and modified atmosphere packaging. In this review, factors responsible for the spoilage of cottage cheese during storage and the methods to extend its shelf‐life are discussed. 相似文献
995.
In this research, potential of reusing bleach water bath was examined with respect to its effect on whiteness of the cotton fabric exposed to 50 g/h of ozone on pilot scale for 45 min with 3 kg of fabric charged fresh at each trial, along with the evaluation of the economic viability of this technology in terms of profit per batch as well as profit per unit product (fabric) computed by Cost of Goods Sold statement. Results have shown that water can be reused with insignificant change in whiteness, revolving around 54% and 60%, and that it harnesses a 7 Rupees profit per unit fabric or 21 Rupees profit per cycle, which seems quite acceptable at existing bleached fabric sale price. 相似文献
996.
Exergy indicates the maximal energy that can do work effectively. Different from optimization of product quality or calculation of generic energy conservation in most previous studies, the application of exergy analysis and exergy cost optimization in petrochemical industry is of great economic and environmental significance. Based on the main fractionator in Jiujiang Petrochemical Complex No. 2 FCCU, an enhanced exergy cost optimization under different operating conditions by adjusting set points of temperature and valves opening degree for flow control is studied in this paper in order to reduce exergy cost and improve the quality of energy. A steady-state optimization algorithm to enhance exergy availability and an objective function comprehensively considering exergy loss are proposed. On the basis of ensuring the quality of petroleum products, the economic benefits can be improved by optimizing the controllable variables due to the fact that exergy cost is decreased. 相似文献
997.
The enhancement of the productivity of the solar desalination system, in a certain location, could be attained by a proper modification in the system design. Therefore, different design configurations could be found in literatures. However, the increase in the system productivity with high system cost may increase also the average annual cost of the distillate. Cost analysis of different design configurations of solar desalination units is essential to evaluate the benefit of modification from the economical point of view. The main objective of this work is to estimate the water production cost for different types of solar stills. In this paper 17 design configurations are considered. Systems with higher and lower values of productivity are considered in this investigation. A simplified model for cost analysis is applied in this study. The results show that, the best average and maximum daily productivity are obtained from solar stills of single-slope and pyramid-shaped. The higher average annual productivity for a solar still is about 1533 l/m2 using pyramid-shaped while the lower average annual productivity is about of 250 l/m2 using modified solar stills with sun tracking. The lowest cost of distilled water obtained from the pyramid-shaped solar still is estimated as 0.0135 $/l while highest cost from the modified solar stills with sun tracking is estimated as 0.23 $/l. 相似文献
998.
The demand for electricity in the Maldives continues to increase by more than 11% in recent years. This is mainly due to the growing number of high-rise air-conditioned buildings and the increasing use of electrical appliances in the residential and commercial sector. This paper investigates potential cost savings and emission reductions achieved by installing different insulation materials of optimum thickness in building's walls. The paper also investigates the effect when air gaps are introduced in the wall. The optimum insulation thickness is based on the cost benefits of each insulation material over its lifetime. This study found that by introducing optimal thickness of different insulation materials and by having air gaps of 2 cm, 4 cm and 6 cm, energy consumption and emissions can be reduced by 65–77%, in comparison to a wall without insulation or air gaps. And, hence have considerable cost savings. 相似文献
999.
随着铜加工行业间的竞争加剧,成本竞争力体现了铜加工企业的核心竞争力,江西铜业铜合金材料有限公司从2007年正式全面投产以来,积极探索成本管理的新路子。通过推行"全面预算管理理念,重点控制生产环节,抓住液化气单耗这个"牛鼻子",大力提倡全员参与成本控制的成本管理思路",逐渐摸索出一套具有铜加工企业特色的成本管理模式,取得了良好的经济效益和社会效益。 相似文献
1000.