Variation in rubber chemistry and dynamic mechanical properties of the milking liner barrel with age

The milking liner is the interface between the milking machine and the cow. Liner properties important to milking performance were investigated for liners of different ages using discriminating tests rather than the normal, rubber-industry quality control-based tests. Large variations in the liner mechanical properties occurred depending on where the sample was taken; stiffness increased 4-fold 40 to 50 mm below the top of the liner. This was related to changes in the chemistry of the rubber created by absorption of milk-derived products (MDP) into the rubber and losses of formulation components, particularly 50% of the plasticizer and all of the antidegradent 40 to 50 mm below the top of the liner, with age and use. The presence of MDP leads to calcium and phosphate deposits on the inner surface of the liner barrel where the MDP was absorbed. The detailed liner properties can be used to explain the forces on the cow's teat and its reactions and effects on milk flow behavior, and to guide future liner development.     

Edge glue clamp carrier glue line pressures based on pulling shims in the glue line

2 =0.90). As the maximum clamp spacing to ensure a particular glue line pressure depends on the distance to the first glue line, a look-up table, based on a minimum glue line pressure of 345 kPa (50 psi), was produced giving the maximum recommended clamp spacings for common clamp face to glue line widths.

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pinus radiata ), wurde ein deutlicher Zusammenhang zwischen dem Leimfugendruck und dem Abstand von Zwingenbacke zur Leimfuge und dem Zwingenabstand gefunden (r²=0.90).Da der maximale Zwingenabstand der ben?tigt wird, um einen bestimmten Leimfugendruck zu erzielen vom Abstand zur ersten Leimfuge abh?ngt, wurde eine Nachschlagetabelle entworfen, welche auf einem Leimfugendruckminimum von 345 kPa beruht, und welche die maximalen Zwingenabst?nde für übliche Abst?nde von Zwingenbacke zu Leimfuge empfiehlt.

     

The influence of compression wood and microfibril angle on the occurrence of distortion in window frames made from radiata pine (Pinus radiata)

D. Don) was examined for the occurrence of crook, bow and twist, and divided into two categories of samples, those with severe distortion, and those with negligible distortion. Ten samples in each category were examined. Small sections of window frame were extracted from the affected areas of the samples in the case of timber showing distortion, and at random for the control samples. Compression wood was assessed by image analysis from scanned images of the end grain, to give a percentage value. Each growth ring was examined microscopically to determine the severity of the compression wood if present and to determine the average microfibril angle in each ring. The microfibril angle gradient across the timber was then calculated. Results indicated that compression wood percent and distribution, average microfibril angle, and microfibril angle gradient, had a significant influence on the occurrence of distortion in these samples. Samples showing distortion altogether had high levels of compression wood, high microfibril angles, or high compression wood or microfibril angle gradients. On average, samples with high levels of distortion had 15% visual compression wood, an average microfibril angle of 32°, and a microfibril angle gradient of 12°, compared to 7%, 24°, and 7°, respectively for the control samples. Compression wood, where present, was typically of the mild type with intercellular spaces and a highly lignified S2L region in the cell walls of tracheids. For the majority of samples identified as containing compression wood, a highly lignified S2L region in the cell wall was the only anatomical feature present. This suggests that abnormal cell wall chemistry may be a significant factor in determining the dimensional stability of sawn timber and remanufactured products.     

Wind velocity directional fluctuation prediction model

A two-dimensional analytical model of wind directional fluctuation exceedence rates is presented. The model assumes that wind directional fluctuations are binormally distributed. The model correctly predicts the trends but tends to underestimate the exceedence rates. Improvements by making the model three-dimensional are outlined.     

Greenways, blueways, skyways and other ways to a better London

“ Landscape planners are quick to criticise other professions for single-use planning, but we tend towards the same mistake when planning greenways and urban greenspace.” This proposition is illustrated by the great series of open space plans which was prepared for London between 1929 and 1976. It is then discussed from a theoretical standpoint with reference to Christopher Alexander, the ‘pattern analysis’ approach to landscape planning, and the author's 1991 report to the London Planning Advisory Committee, Towards a Green Strategy for London. The paper concludes that ‘greenway’ is an excellent marketing term, but that product diversification and product differentiation must take place. We need special varieties of greenway for special purposes. Brief Alexander-type patterns are outlined for seven varieties: parkway, blueway, paveway, glazeway, skyway, ecoway and cycleway.     

Exit flow measurements of a centrifugal pump impeller

Discharge flows from a centrifugal pump impeller with a specific speed of 150 [rpm, m³/min, m] were experimentally investigated. A large axisymmetric collector instead of a volute casing was installed to obtain circumferentially uniform flow, i.e. without interaction of the impeller and the volute. The unsteady flow was measured at the impeller exit and vaneless diffuser using a hot film probe and a pressure transducer. The flow at impeller exit showed pronounced jet-wake flow patterns. The wake, which was on the suction/hub side at high flow rate, became enlarged pitchwisely on both the hub and the shroud side as the flow rate decreases. The pitchwise non-uniformity of the flow rapidly decreased along the downstream and the nonuniformity almost disappeared at radius ratio of 1.18 for medium flow rate. The mean vaneless diffuser flow was reasonably predicted using a one dimensional analysis when an empirical constant was used to specify the skin friction coefficient. The data can be used for a centrifugal pump impeller design and validation of CFD codes and flow modeling.     

视频流正向云端迁移

私有云适合对连续性和安全性要求高的应用,公有云则适合有波动需求和需要多址协同的应用,云端视频制作还受到商业模式和应用需求的影响     

A congruence rule format for name-passing process calculi

We introduce a GSOS-like rule format for name-passing process calculi. Specifications in this format correspond to theories in nominal logic. The intended models of such specifications arise by initiality from a general categorical model theory. For operational semantics given in this rule format, a natural behavioural equivalence—a form of open bisimilarity—is a congruence.     

Shift From Coke to Coal Using Direct Reduction Method and Challenges

 Ironmaking involves the separation of iron ores. It not only represents the first step in steelmaking but also is the most capital intensive and energy intensive process in the production of steel. The main route for producing iron for steelmaking is to use the blast furnace, which uses metallurgical coke as the reductant. Concerns over the limited resources, the high cost of coking coals, and the environmental impacts of coking and sinter plants have driven steelmakers to develop alternative ironmaking processes that can use non coking coals to reduce iron ores directly. Since the efficiency and productivity of modern large capacity blast furnaces will be difficult to surpass, blast furnaces will continue to retain their predominant position as the foremost ironmaking process for some time to come. The alternative ironmaking processes are therefore expected to play an increasingly significant role in the iron and steel industry, especially in meeting the needs of small sized local and regional markets. It is likely that the importance of direct reduced iron (DRI) and hot metal as sources of virgin iron will continue to increase, especially in the developing countries where steelmaking is, and will be, primarily based on electric arc furnace (EAF) minimills. Consequently, the challenges that are faced by the new technology have to be embraced.