刮板输送机的设计与使用

<正>刮板输送机是一种挠性牵引的连续运输机械,其运输能力不受货物的块度和湿度影响,具有机身高度小,便于装载,长短调整方便,移置容易,机体坚固等特点,在粮食、油脂、饲料、食品、化工、建材等行业得到了广泛的应用。刮板输送机在饲料厂的使用也很     

对U型槽刮板输送机设计中若干问题的探讨

<正> 目前,在生产和使用U型槽刮板输送机中还存在一些问题,如:浮链、输送链及链轮齿形的标准选用、链板的结构等。解决这些问题,有利于生产、使用、维修这种刮板输送机。一、浮链在使用U型槽刮板输送机中,有载分支的刮板输送链有时出现浮链,这使生产和使用厂家感到棘手。为了解决浮链问题,笔者对部分厂家的U型槽刮板输送机进行了调查,发现这样的现象:新安装的刮板输送链的刮板垂直于料槽底部,如图1中实线所示;使用刮板输送链一段时间后,刮板产生塑性变形,如图1中虚线所示。这一现象说明,浮链的成因来自于刮板及附板的结构。目前刮板的结构如图1,安装时刮板与链铰链中心线垂直,链板上焊接了一块附板,附板与刮板螺栓联接,附板为平面     

水平埋刮板输送机的理想临界输送速度

<正> 目前,水平埋刮板输送机(MS16～40,刮板输送链为DT、GT、BU_1)的输送速度较低,推荐的输送速度选择范围为0.08～0.8m/s,常用的输送速度为0.16～0.45m/s。如果在使用中能提高现有输送速度,无疑可有效地提高输送能力,或降低输送机材料消耗。而提高输送速度,这与输送机固有的临界输送速度有关。所谓水平埋刮板输送机的临界输送速度,是指被输送物料成整体稳定料流前进时,有载分支的刮板输送链的最大平均速度。本文介绍水平埋刮板输送机在理想(即不计驱动链轮与刮板输送链的啮合冲击的影响)条件     

刮板输送机选型原则与参数确定研究

刮板输送机是一种以挠性体作为牵引机构的连续动作式运输机械,它主要用于煤矿的回采工作面或顺槽等其他场所。由于其特殊的结构和工作环境,刮板输送机迄今为止仍是综采工作面唯一的运输设备。把刮板链视为刚体进行受力分析,就难以真实地揭示其产生动载荷的规律和运动过程中的本质问题。本文以安徽某矿为例,阐述了刮板输送机选型基本原则,分析了如何确定主要参数,其设计思路具有一定的推广应用价值。     

刮板输送机和液压支架配套分析

刮板输送机和液压支架设备之间的配套应用不仅提升了整个设备的生产性能,同时还延长了设备的使用寿命。在实际的生产中,这种设备类型的应用具有现实意义。本文主要从设备的生产能力,配套设备所占空间以及连接的形式和强度等方面的问题进行介绍和分析,希望能够给相关的设备应用工作人员提供借鉴和参考。     

大型可伸缩带式输送机的应用

可伸缩带式输送机是指可以根据工作面位置变化来调整自身长度的一种带式输送机。适用于采煤工作面中的顺槽运输和可伸缩挖掘。带式输送机现正向大输送能力和大单机长度的方向发展,其输送量已达2000t/h,单机铺设长度达3000m。本文根据输送机的发展和改善,使用简单易懂的话讲述了可伸缩带式输送机的基本结构,工作方式以及在现实煤矿的生产活动中,它利用自身的大容量的优势,在煤矿工业中发挥的实际性作用。     

同步覆压带大倾角带式输送机的探索设计

针对目前大倾角带式输送机存在的块状物料易下滑滚落发生事故的技术难题,以及目前不太理想的解决方法,开辟新思路,探索性设计了覆压式带式输送机,通过理论研究分析,该型带式输送机可从根本上解决大倾角带式输送机块状物料下滑滚落问题,避免发生伤人事故。     

如何解决埋刮板输送机的“浮链”问题

“浮链”是埋刮板输送机工作中常出现的问题,调节张紧装置以改善浮链现象是有效的,但解决浮链的根本措施在于设计。     

刮板输送机常见的故障与排除

<正>刮板输送机是一种在敞开槽内、借助于运动着的刮板链条连续输送散状物料的运输机械,是饲料厂常用的水平输送设备。由于其运载量大、密封性好、运转平稳、坚固结实,以及能多点进料和多点卸料等优点,在饲料企业得到了广泛的应用。刮板输送机工作正常与否,对生产工艺顺利进行和安全生产都至关重要。     

Prevention of intramammary infections in dairy cows by the use of a premilking teat dip method with a foaming iodophor dip agent

In this study we investigated the efficacy of premilking teat dipping with a foaming iodophor teat dip in a negative controlled field study. Incidence of new intramammary infections (IMI), incidence of clinical mastitis, influence on somatic cell count (SCC) and the characteristics of udder tissue and teats were used as parameters to evaluate clinical efficacy. Predipping was compared with a negative control using a split-udder experimental design. Right teats were predipped with a foaming disinfectant containing 0.27% iodine while left teats served as controls. The latter were conventionally cleaned with damp cloth towels and dried manually with disposable paper towels ("best cleaning practice"). All teats were dipped after milking with the same dip. There were no differences between treated and control quarters with respect to incidence of new IMI during the study period (treated quarters: 6.6% vs. untreated: 6.95%), incidence of clinical mastitis (30 cases in the treatment group vs. 39 cases in the control group) and geometric mean of SCC of quarter milk samples. Spectrum of detected pathogens was also comparable. Condition of udder tissue and teat ducts did not differ between treated and control quarters.     

规模养殖户病历档案的应用

随着集约化养殖场在农村的不断兴建，成千上万头（只）规模的养殖专业户在农村己屡见不鲜。及时建立病历档案，对搞好畜禽的饲养管理和疾病防治，提高养殖户的经济效益具有十分重要的意义，我县养鸡专业户卢某的蛋鸡场．常年饲养蛋鸡10000余只。年均经济效益在10万元以上．他的成功秘诀．就是建立病历档案。十几年如一日，从不间断．收益不浅。现将病历档案的书写原则，记载内容和应用体会介绍如下：     

Storage quality and marketability potential of bagged silage for smallholder dairy farmers in Zimbabwe

Bagged sole maize and maize–cowpea silages in three bag sizes were assessed at 42 and 282 d post-ensiling for sensory and chemical quality. A survey of dairy farmers on silage use and preferences was conducted in the Chikwaka communal area and Marirangwe small-scale commercial farming area. Only silage dryness changed with time. Percentage neutral detergent fibre significantly changed in 20?kg bags from 58.1 ± 0.75% at 42 d to 52.3 ± 0.86% at 282 d and in 10?kg maize–cowpea bags from 48.6 ± 0.75% to 56.0 ± 0.86%. Percentage crude protein significantly decreased (P < 0.05) for 15?kg (11.8 ± 0.30% to 9.4 ± 0.35%) and 20?kg bags (11.4 ± 0.30% to 8.9 ± 0.35%) for maize– cowpea. All 45 farmers surveyed knew about silage and 90% were feeding it to cows, 53% were making their own and 37% purchased silage. Challenges in making silage included unavailability of forage choppers, lack of requisite resources and inadequate knowledge. Silage unavailability and difficulties in transportation and storage resulted in a low frequency of silage purchases. There was no association (χ2 0.18; P > 0.05) between farming system and farmers’ willingness to buy or sell silage, and larger bags were preferred (χ2 78.96; P < 0.05). Computed silage costs per tonne were farm-produced sole maize US$57.54, maize–cowpea US$58.59 and bought-in sole maize US$89.80.     

Flumethrin: a non-stripping pyrethroid dip for the control of sheep scab

Flumethrin, a synthetic pyrethroid, used in the laboratory as a sheep dip (Bayticol) at a concentration of 55 ppm, eradicated sheep scab from 30 infested sheep and provided protection against infestation for at least seven weeks. Similar results with at least five weeks protection were obtained on monitor sheep dipped under field conditions with flocks of 525 and 870 sheep. The dip was prepared and replenished with 66 ppm flumethrin and the concentration did not strip.     

The clinical effectiveness of a post milking teat disinfection method with a foaming iodophor teat dip

The effect of postmilking teat dipping with a foaming iodophor agent on incidence of intramammary infections (IMI), incidence of clinical mastitis, somatic cell count and the characteristics of udder tissue and teat was investigated in a positively controlled field study. Two groups of animals were compared. Teats were dipped with a foaming iodophor in the treatment group (TG, 122 animals) while teats in the control group (CG, 121 animals) were dipped with a conventional iodophor teat dip with the same iodine content. A bacteriological examination of quarter milk samples divided the study period in two parts. The incidence of new IMI did not differ between the groups (1st part of trial: TG vs. CG: 6.84% vs. 9.16%, 2nd part of trial: 7.78% vs. 7.82%). There were no differences between the treatment groups regarding incidence of clinical mastitis. We detected 0.64 clinical cases per 100 days in the treatment group vs. 0.50 in the control group. The development of SCC was comparable in both groups. Teat skin and teat duct conditions showed variation during the study period. Clinical efficacy of postmilking teat disinfection with a foaming iodophor was comparable to the treatment with a conventional iodophor product.     

The bactericidal activity of a teat dip containing chlorhexidine and cetrimide.

Using an in vivo test on teat skin the disinfectant activity of a teat dip containing chlorhexidine and cetrimide was compared with two iodophor solutions, one containing the recommended concentration of 0.5 per cent available iodine and the other a 10-fold dilution of this (0.05 per cent iodine). The test organisms used were Staphylococcus aureus and Escherichia coli and for both species the 0.5 per cent iodophor was significantly more bactericidal than either the diluted iodophor or the chlorhexidine/cetrimide teat dip (P less than 0.01). In the test against S aureus, chlorhexidine/cetrimide and the 0.05 per cent iodophor showed similar bactericidal activity, but the iodophor was significantly more bactericidal against E coli (P less than 0.01). It is argued that due to its low bactericidal activity this formulation of chlorhexidine/cetrimide is likely to be inferior to 0.5 per cent iodophor solution as a disinfectant teat dip.     

In vitro and in vivo evaluation of a 0.5% chlorhexidine gluconate teat dip

The activity of a 0.5% chlorhexidine gluconate postmilking teat germicide in reducing the numbers of Staphylococcus aureus and Streptococcus agalactiae on the skin of excised teats from cows was determined. The product yielded logarithmic reductions of 4.09 and 4.10 against S aureus and Str agalactiae, respectively, compared with 3.80 and 3.81 reductions, using a 1% iodophor dip. Germicide tolerance to an organic load containing Serratia marcescens or Pseudomonas spp was also determined. Organisms were not recovered from the product 8 hours after introduction of a simulated organic load containing either species of bacteria. The germicide was further evaluated against S aureus and Str agalactiae, using experimental challenge-exposure procedures in a research dairy herd. Efficacy was 73.4% (P less than 0.001) against S aureus and 68.1% (P less than 0.005) against Str agalactiae.     

Design and storage stability of reference materials for microfluidic quantitative PCR-based equine gene doping tests

One method of gene doping in horseracing is administering of exogenous genetic materials, known as transgenes. Several polymerase chain reaction (PCR)-based methods have been developed for detecting transgenes with high sensitivity and specificity. However, novel designs for reference materials (RMs) and/or positive template controls (PTCs) are necessary for simultaneous analysis of multiple transgene targets. In this study, we designed and developed a novel RM for simultaneously detecting multiple targets via microfluidic quantitative PCR (MFQPCR). Twelve equine genes were selected as targets in this study. A sequence region including primers and probes for quantitative PCR was designed, and a 10 bp sequence was inserted to allow the RM to be distinguished from the original transgene sequences. The sequences of individual detection sites were then connected for 12 genes and cloned into a single plasmid vector. We performed fragment size analysis to distinguish between the PCR products of the original transgene sequence and those of the RM, enabling identification of RM contamination. PTCs diluted to 10,000, 1,000, 100, and 10 copies/µl with horse genomic DNA from RM were stably stored at 4°C for 1 year. As digital PCR enabled absolute quantification, the designed substances can serve as an RM. These findings indicate that the RM design and storage conditions were suitable for gene doping tests using MFQPCR.