Simulating the displacement of a heavy oil by a lighter oil in an offshore production line

An analysis was conducted on the displacement of a heavy fluid by a miscible light fluid in the flow assurance operation of injecting diesel oil to displace heavy oil in an insulated offshore production line. A three-dimensional computational fluid dynamics model was developed and implemented in OpenFOAM®. It stimulates the production stages, no-touch time, and oil displacement, considering heat transfer through natural convection and conjugated heat transfer through the solid layers of the pipeline. The specific test case focused on the first 180 m of an existing offshore production line. The simulations revealed two primary mechanisms of mixing: turbulence and secondary flows generated by the pipeline curves. Remarkably, the results demonstrate that by injecting a volume of lighter oil 1.3 times the pipeline volume, approximately 90%–95% of the heavy oil can be effectively removed.     

浅析军工产品研制生产的质量管理

本文阐述了军工产品质量体系的发展及军工产品研制生产的质量管理,对研制生产中严格执行国军标的必要性进行了分析。     

Milking machine test survey of British installations: An update

A review of milking machine tests on 640 dairy farms in England and Wales between 2012 and 2014 suggests more machines now comply with installation and operation standards than 10 years ago. However, approximately 60% of systems tested failed to meet the milking machine requirements of the farm assurance standards in the UK, with most failing to reach operational requirements on one aspect. The most common problem (47%) was that the systems had excessive vacuum line losses, with other vacuum/airline losses also common. Many machines failed on more than one aspect.     

Dairy cow handling facilities and the perception of Beef Quality Assurance on Colorado dairies

A survey was conducted on Colorado dairies to assess attitudes and practices regarding Dairy Beef Quality Assurance (DBQA). The objectives were to (1) assess the need for a new handling facility that would allow all injections to be administered via DBQA standards; (2) establish if Colorado dairy producers are concerned with DBQA; and (3) assess differences in responses between dairy owners and herdsmen. Of the 95 dairies contacted, 20 (21%) agreed to participate, with a median herd size of 1,178. When asked to rank the following 7 traits—efficiency, animal safety, human safety, ease of animal handling, ease of operation, inject per Beef Quality Assurance (BQA) procedures, and cost—in order of priority when designing a new handling facility, human and animal safety were ranked highest in priority (first or second) by the majority of participants, with ease of animal handling and efficiency ranked next. Interestingly, the administration of injections per BQA standards was ranked sixth or seventh by most participants. Respondents estimated the average annual income from the sale of cull cows to be 4.6% of all dairy income, with 50% receiving at least one carcass discount or condemnation in the past 12 mo. Although almost all of the participating dairy farmers stated that the preferred injection site for medications was the neck region, a significant number admitted to using alternate injection sites. In contrast, no difference was found between responses regarding the preferred and actual location for intravenous injections. Although most participating producers are aware of BQA injection guidelines, they perceive efficiency as more important, which could result in injections being administered in locations not promoted by BQA. Dairy owners and herdsmen disagreed in whether or not workers had been injured in the animal handling area in the last 12 mo. Handling facilities that allow for an efficient and safe way to administer drugs according to BQA guidelines and educational opportunities that highlight the effect of improved DBQA on profitability could prove useful. Dairy producers play a key role in ensuring that dairy beef is safe and high quality, and just as they are committed to producing safe and nutritious milk for their customers, they should be committed to producing the best quality beef.     

Limiting mycotoxins in stored wheat

The quality of harvested wheat grain can deteriorate markedly during the post-harvest management stages. Biotic factors, such as grain type and ripeness, coupled with the prevailing abiotic factors, such as water content and temperature, and also preservative concentration will influence the safe storage life and the level of contamination with mycotoxins. These mycotoxins include deoxynivalenol (DON) produced pre-harvest and zearalenone (ZEA) produced post-harvest by Fusarium graminearum and Fusarium poae, respectively, ochratoxin (OTA) produced by Penicillium verrucosum post-harvest in cool damp northern European climates, and perhaps T-2 and HT-2 toxins produced by Fusarium langsethiae. This review presents recent data on the relationship between dry matter losses caused by F. graminearum under different environmental regimes (water activities, temperatures) and the level of contamination with DON. This is important as poor post-harvest drying and storage management may exacerbate DON contamination already present pre-harvest. It is thus critical to relate the environmental factors in stored wheat grain during storage, especially of intergranular relative humidity (RH) and temperature, to safe storage periods without spoilage or risk from increased DON contamination. The growth/no growth and DON/no DON (F. graminearum) and OTA/no toxin production (P. verrucosum) have been used to build a model with a simple interface to link temperature and RH values to the potential risk level which may allow growth or toxin production. This paper also considers the use of modified atmospheres, preservatives and biocontrol to minimise DON and OTA in moist wheat grain. These approaches together with clear monitoring criteria and hygiene could contribute to better post-harvest management of stored temperate cereals and ensure that mycotoxin contamination is minimised during this key phase in the food/feed chain.     

Biogenic amines in fish,fish products and shellfish: a review

Fish, cephalopods and shellfish provide a healthy source of high-quality proteins, essential vitamins, minerals and polyunsaturated fatty acids. The beneficial effects of fish consumption on human health such as protection against coronary heart disease and certain cancer may be offset by fish decomposition and the formation of chemical contaminants such as biogenic amines. There are several toxicological effects of biogenic amines on humans, especially histamine. It is the causative agent of histamine or scombroid fish poisoning which is a significant public health problem. In individuals with diminished histamine detoxification, ingestion of even a low or moderate histamine- or tyramine-containing fish may lead to food intolerance. Biogenic amines such as putrescine, tyramine and cadaverine can potentiate histamine toxicity. Furthermore, dietary polyamine intake should be minimised in some cancer patients. Besides their potential toxicity, biogenic amines are used for the evaluation of hygienic quality of different marine and freshwater species. Spoilage pattern and biogenic amine formation are species specific. Histamine has been traditionally used as an indicator of the quality of histidine-rich fish (dark-muscle fish). On the other hand, putrescine and cadaverine are the most objective indicators of quality of histidine-poor fish (white-muscle fish), shellfish and fermented seafood products.     

机器视觉在轨道交通系统状态检测中的应用综述

城市轨道交通系统主要由弓/网系统、轨道线路、车辆、车站等组成,传统的人工巡检等方法检测效率低、劳动强度大、自动化和智能化程度不高,给城市轨道交通的运营保障和进一步健康发展带来了巨大的挑战.机器视觉作为一种重要的检测手段,在城市轨道交通系统状态检测领域得到了广泛的应用.鉴于此,针对机器视觉在城市轨道交通系统安全状态检测中...     

中小型引水式水电站调压阀尺寸优化

为保证工程安全并降低造价,中小型引水式水电站多采用调压阀作为调节保证措施,调压阀直径的确定不仅直接影响工程投资,且涉及到系统的平压效果。通过分析不同运行工况、水道系统最大压力上升值、机组转速上升率、事故甩负荷导叶关闭时间等多种因素对调压阀直径的影响,提出了合理的调压阀直径选取需满足的原则,并结合某电站调压阀直径的优化计算,验证了理论分析提出的原则。