Constructional aspects of some heated concrete floors for greenhouses

The paper gives particular attention to the constructional aspects of concrete floors in greenhouses.In 1979 preliminary research was started in IMAG into the cultivation of vegetable seedlings on several floor materials, namely on ordinary concrete, porous concrete and asphalt. Overhead watering was provided, and the heating system was in the soil below the floor.These experiments revealed two problems. Uneven water distribution caused uneven growth and the mass of soil around and the concrete above the heating tubes caused a long response time for warming up and cooling down the concrete surface. For strength and wear resistance the ordinary concrete turned out to be the only suitable material.In 1981 IMAG made further trials with floors where heating and (flooded) watering system were integrated in the floor. These floors were made of reinforced concrete cast in situ, of asbestos cement and of concrete tiles. The 100 mm thick concrete floor cast in situ, turned out to be the most suitable because of the loading capacity and the good drainage of water. A standard specification was prepared for this floor type. At the end of 1985, applications of concrete floors in greenhouse, extended to 150 ha in the Netherlands for the production of vegetable seedlings, pot plants and cut flowers in pots or mats. If this trend continues there will be about 600 ha by 1990.Further development of the concrete floor has the objectives of improving thermal behaviour and easier removal or restoration of a floor. For that purpose two types of floor are under trial.

• 1.(1) An insulated concrete floor cast in situ that contains less concrete per square meter.
• 2.(2) A concrete floor built from removable concrete elements combined with a system for air movement between the plants.

     

Drainage Properties and Ammonia Emissions in Slatted Floor Systems for Animal Buildings

Drainage properties of and ammonia emissions from slatted floors and drainage channels were investigated using a laboratory arrangement development for the purpose. The arrangement consists of a steel-framed box with two levels in order to simulate different slatted floor systems. The slatted floor under test is laid on the top level and manure is dropped on to it from various heights. The lower level consists of a drainage channel, the top of which is covered by a lid perforated with holes of different shapes.Drainage experiments on slatted floors for cows with slits from 30 to 45 mm wide showed an average total drainage value for faeces and urine of 72% and an average urine drainage value of 82%. Drainage experiments on slatted floors for pigs showed results varying between 38 and 46% for total drainage depending on different drainage arrangements. The best drainage capacity was obtained when the drainage channel cover had holes giving a large drainage area.The ammonia experiments on slatted floors for cows with 2 and 30 mm spacing showed an accummulated ammonia emission of about 8 and 3 g respectively, during the 20 h testing period. On slatted floors for fattening pigs, the accumulated ammonia emission was calculated to be about 2 g during the 20 h testing period. These ammonia emission results are related to the mass quantities and the nitrogen contents of faeces and urine, which normally are dropped to slatted floor surfaces in animal buildings.     

Reduction of Dust Concentration and Exposure in Pig Buildings by Adding Animal Fat in Feed

Dust concentrations were reduced by 35–60% in pig buildings, while human dust exposure was lowered by 50–70% by adding 4% animal fat to the feed. However, there is still a large quantity of airborne dust in these buildings and workers should reduce their exposure risk to the high concentrations by wearing a dust mask. Variations exist in dust concentrations for total dust in pig buildings. The respirable dust fraction does not appear to be location-dependent and therefore may be a better indicator for evaluating dust reduction methods. Further studies are needed to find the nature of these variations in total dust concentration, so that a representative measurement can be determined for a pig building. Total dust levels found by a personal sampler were from three to seven times larger than total dust concentrations measured by a stationary sampler. Relationships between values from personal and stationary dust samplers need to be explored for livestock environments, and improved dust measurement criteria established for evaluating dust suppression practices.     

Volatilization of Ammonia from Dairy Housing Floors with Different Surface Characteristics

The relation between surface characteristics and urease activity was studied for samples (300×300 mm) from 50 different specimens representative of concrete floors in dairy cow houses, since volatilization of NH₃from urine pools on floors is reduced when urease activity on the floor surface is reduced, provided that urease activity is below a certain level. Variations within the factors “concrete strength”, “treatment of the fresh concrete surface”, “curing time” and “treatment of the hardened concrete surface” were applied. The specimens were split into two groups, namely non-coated and coated specimens.Floor surface roughness was measured for samples from all specimens, and also water penetration depth was measured for samples of the non-coated specimens. Samples from all 50 specimens were fouled with cow faeces and urine for 15 days and urease activity was measured.By relating urease activity of the samples from the non-coated specimens to the roughness of the floor surface and the water penetration depth, 67% of the variance was explained. This was 25% for the coated specimens, using a relation between surface roughness and urease activity. By expressing urease activity on the non-coated specimens as a function of the factors “concrete strength”, “treatment of the fresh concrete” and “curing time” and the factor levels within, 87% of total variance was accounted for.Although the experimental fouling period was relatively short compared with the length of the animal housing period, urease activity on most of the non-coated samples, on average, reached values out the range in which a reduction of volatilization of ammonia from a urine pool is found when urease activity is reduced. Coated specimens in general and, in particular, non-coated specimens of which the mould side was tested, demonstrated urease activities within that range.The durationof the fouling period during housing of the cows and the basics of the formation of urease activity on floor surfaces both support the idea that build up of urease activity proceeds after 15 days of fouling. The urease-active top layer on the floor surface is expected to cause gradual diminishing of the influence of floor surface characteristics on emission of ammonia from urine pools deposited on the floor. High levels of urease activity were expected to develop on all types of floors, either coated or non-coated. Impregnating and coating of floors in dairy cow houses were therefore not expected to result in a reduction of emission of ammonia. Only floor cleaning strategies removing or inactivating the urease on the floor were expected to result in such a reduction.     

基于单视角点云镜像的猪只体尺测量方法

为了克服人工家畜体尺测量耗时、应激大和工作强度大等问题,提出了一种基于单视角点云镜像的猪只体尺测量方法。首先使用单Xtion深度相机采集包含猪体的场景点云图像序列,并人工筛选出包含背部弯曲程度较小猪体的场景点云图像,然后基于随机采样一致性算法和聚类分割算法自动化分割目标猪体并对其进行姿态归一化,检测单视角猪体点云对称面,并利用对称面镜像获取完整猪体,最后利用自主研发的体尺测量软件测量猪只体尺。试验结果表明,利用该方法测量体长的平均相对误差为5.00%,臀宽测量的平均相对误差为7.40%,臀高测量的平均相对误差为5.74%。该方法为猪只体尺测量提供了切实可行的新途径。     

金华猪精准养殖与管理技术

在搜集、分析以家猪为代表的畜禽生长信息采集、畜禽图像处理的应用研究现状后,结合现代养猪工艺和金华猪生长习性,指出金华猪养殖产业迫切需要引入猪只体尺测量、估测猪体质量、智能饲喂设备（代谢笼）、数字化管理4个方面的精准养殖技术及其配套的智能化养殖设施,以期实现金华猪的现代化养殖与管理。      

规模化养猪场粪水处理和资源化利用关键技术

随着我国畜禽养殖业的迅猛发展,养猪场粪污集中排放对环境的影响越来越大,有效处理和合理利用猪场粪污迫在眉睫。通过对目前规模化养猪场污水处理工艺、技术、进行总结分析,为规模化畜禽养殖场粪污处理提供参考。      

轮胎摩擦力与滑移率关系模型的建立方法

通过分析描述轮胎摩擦力与滑移率关系的Magic模型,根据其关系曲线形状进行假设,利用二阶系统传递函数的直接识别方法,得到了由指数函数和双曲函数组成的简单建模方法,所建模型能够准确地描述摩擦因数与滑移率间的变化关系。     

家畜智能养殖设备和饲喂技术应用研究现状与发展趋势

家畜智能养殖设备是智能农机装备的组成部分之一,是国际农业装备产业技术竞争的焦点。本文重点围绕家畜智能养殖设备与饲喂技术在实践中的应用,进行了系统的性能特点分析。目前家畜智能养殖设备的开发对象主要针对猪和奶牛,主要研发的系统包括妊娠母猪电子饲喂站、哺乳母猪精准饲喂系统、奶牛精准饲喂系统和挤奶机器人等。家畜智能养殖设备的工业化应用必须与养殖模式、畜舍结构布局结合起来,才能发挥设备的使用效率,同时从满足动物的福利出发,与动物生理、生长及行为结合起来,形成设备与动物的互作和相互适应。最后指出了智能设备的研究必须与畜牧业生产的理论、目标产品的功能驱动及养殖方式的创新协调一致,要不断地更新换代,才能助推畜牧业的转型升级。     

叫声在生猪福利监测中的研究进展与挑战

叫声是评估生猪福利水平的重要方式之一。本文首先分析了生猪叫声与福利之间的相互关系。其中，与生猪福利密切相关的三种生猪叫声包括咳嗽声、尖叫声和呼噜声。基于这三种声音进一步分析声音与环境，声音与身体状况，以及声音与健康之间的关系。随后，对当下的生猪福利监测所采用的传感器，包括穿戴式与非接触式两大类进行分析，并简述不同方式的优劣势。基于非接触式的优势及麦克风传感器技术的可行性，从声音的获取和标记、特征提取以及声音分类三个方面对现有的生猪声音处理技术进行了阐述和评估。最后，从声音监测技术、生猪个体福利监测、商业应用以及养猪从业者四个角度讨论了叫声在生猪福利监测中面临的研究困境以及发展趋势。研究发现，目前关于生猪声音分析的研究大多集中在分类器的选择和识别算法的改进上，而对端点检测和特征选择的研究较少。同时，当下面临的主要挑战还包括不同生长阶段的音频数据获取难度较高，缺乏公共的猪舍内音频数据库以及缺少完善的声音指标与动物福利监测评价体系。总体来说，建议进一步对声音识别过程中涉及的各部分技术进行深入探索，同时加强跨学科专家之间的合作，共同推动声音监测在生猪实际生产中的应用，从而加快精准畜牧业的实现。     

寒冷地区畜禽粪便沼气发电工程典型案例分析

文章从工艺流程、技术参数、运行状况以及效益分析等方面对宁夏灵农畜牧发展有限公司养猪场内沼气工程进行了技术分析。结果表明,通过全混式厌氧发酵(CSTR)两级工艺,每天可消纳TS为6%的粪污39 m3,产气700 m3,发电1050 kWh,有机肥(沼液和沼渣)39 t。运行表明,采用太阳能耦联沼气锅炉联合增温的方式可解决寒冷地区冬季低温下沼气工程的正常运行问题,该项目的成功对沼气工程在宁夏等寒冷地区的推广应用以及宁蒙灌区畜禽粪便面源污染的控制具有重要的示范效应。     

基于能量损耗的球轴承摩阻力臂计算方法

为了解决水工闸门滚动行走支承的球轴承摩阻力臂计算方法问题,从能量损耗角度出发,将球轴承的滚动摩擦简化为微观滑动、弹性滞后和黏着效应3种.其中微观滑动的接触面近似为圆形区域,其应力分布采用2个相似的＂赫兹＂应力分布式进行叠加,来满足接触边界条件;弹性滞后则是由于滚珠材料并不是完全的弹性材料引起的.当滚珠受外载荷作用时发生变形,在变形过程中由于材料内摩擦作用所引起的结构阻尼将消耗一部分能量,而这部分能量是产生弹性滞后的原因,弹性滞后与应变成正比;黏着效应与接触材料的表面能有关,当滚球在套圈内滚动时滚珠需要克服接触材料的表面能,在克服材料表面能的过程中需要消耗一部分能量,这部分能量就是产生黏着效应的主要原因.通过选用440C不锈钢、氮化硅、碳化硅和碳化钨等滚动轴承中常用的材料进行计算,研究发现球轴承的摩阻力臂与打滑比成正比、与载荷成反比.     

畜禽舍臭味治理技术措施

畜禽舍的异味排放越来越成为畜禽舍建设和运营过程中关注的问题,说明了畜禽舍臭味的来源、危害和控制方法,以及生物处理措施的应用,用一个猪场的实例说明了解决方法,为畜禽舍的臭味治理提出了切实可行的方案。      

考虑压力效应的液压缸摩擦模型研究

应用经典摩擦模型描述液压缸摩擦力时,由于未考虑油液压力效应对摩擦力的影响,模型预测效果欠佳。为了克服该问题,引入压力影响系数和动态摩擦时间常数,基于Stribeck和广义Maxwell滑动模型（GMS）提出了改进的稳态摩擦模型（P-Stribeck）和动态摩擦模型（P-GMS）。搭建了伺服阀控液压缸系统摩擦特性测试实验台,在不同密封形式、不同缸径、不同负载、不同加速度及频率下进行了液压缸往复运动摩擦特性测试。采用智能遗传算法,利用液压缸测试实验台采集的进出口压力、位移、速度、摩擦力等数据,分别采用改进的稳态摩擦模型和动态摩擦模型进行参数辨识和模型检验。对不同复杂工况下实验数据与经典摩擦模型以及所提出的改进模型的预测结果进行对比和误差分析,结果表明：P-Stribeck模型预测液压缸稳态摩擦力的精度明显优于Stribeck模型,P-GMS模型预测液压缸动态摩擦力的精度优于GMS摩擦模型,从而验证了所提出摩擦模型的有效性。     

畜禽舍环境控制及防疫系统试验

为有效控制畜禽舍环境质量,净化空气,该文介绍了一种畜禽舍环境控制的技术措施,利用空气电净化防疫防病技术,构建一套防疫系统。试验结果表明,封闭式保育猪舍的除尘率在70%,细菌率维持在50%。利用空气电净化防疫措施,能够有效削减畜禽舍载畜载禽环境中的粉尘和空气微生物,可有效控制畜禽舍环境质量,净化空气,达到防疫的目的,是一种应用价值很高的有害微生物消灭方法。      

基于滑模极值搜索算法的车辆驱动防滑控制策略

为了提高车辆的驱动防滑能力,提出了一种基于滑模极值搜索算法的驱动防滑控制策略。采用滑模极值搜索算法作为一种自寻优方法找到轮胎力-滑转率曲线的极值点,无需估计路面附着系数和建立理想参考模型就可以将轮胎的滑转率控制在最优滑转率附近,提高车辆的动力性和方向稳定性。在Matlab/Simulink中建立车辆系统仿真模型。仿真结果表明,此控制策略能使车辆在驱动过程中快速达到实时路面条件下的最优滑转率,增强了车辆的动力性能。     

基于主动制动的车辆稳定性系统最优控制策略

引入分层控制概念设计了横摆力矩控制和滑移率控制相结合的车辆稳定性控制系统.建立了侧偏角和横摆角速度具有最佳输出响应的车辆理想模型,采用前馈与反馈控制相结合跟踪理想模型的控制策略,基于最优控制理论设计横摆力矩控制器.通过设计理想滑移率分配模块确定下层滑移率控制器理想值,基于模糊控制理论设计滑移率控制器.在Matlab/Simulink平台上建立8自由度非线性车辆模型,分别在低附着和高附着路面条件下进行了仿真分析.结果表明:采用分层控制可以很好地实现车辆所需横摆力矩,有效地控制车辆质心侧偏角和横摆角速度跟踪理想模型,瞬态及稳态响应良好,改善了车辆操纵稳定性.     

柴油机飞轮法兰过盈装配的设计及校核

介绍了后置齿轮系曲描后端飞轮的两种安装设计方案,并针对通过飞轮法兰与曲轴过盈配合,依靠摩擦传动传递飞轮端扭矩的设计方案,对飞轮法兰与曲轴之间过盈配合表面产生的摩擦扭矩进行了分析计算,并按屈瑞斯卡应力屈服条件对过盈配合表面进行了塑性变形判断,既保证在所传递扭矩的作用下不发生相对滑动,又保证在合理的装配工艺奈件下,配合表面不产生塑性变形,并通过试验验证了计算结果的正确性。该计算过程可以推广应用于类似的圆柱面过盈连接传递扭矩的校核计算。     

A Survey on Concrete Floors in Pig Houses and their Degradation

On farms with fattening pigs, degradation of slatted and solid concrete floors can result in animal injuries and early failure of slat beams. A survey in East and West Flanders was conducted to gauge the extent of this problem, the causes and consequences.Entrusting mixing and placing of the concrete to specialized firms, appeared to increase the life of the floor. However, even concrete slats cast by specialized manufacturers, showed degradation within five years of use on 40% of the farms. No relation could be found between the use of high-pressure cleaning and the speed of attack. The use of cleaners seemed to delay the attack rather than cause degradation. The feeding method had a major influence on attack. The smaller the distance between water and feed supply, the faster the degradation proceeded. Therefore the use of liquid feed made the problems significantly worse. Almost half of the farmers had already taken measures to protect or repair the floor. The life of coatings appeared to be rather limited. Surface layers with ordinary portland cement and ‘‘product S’’, which is said to be based on ground tuff, seemed to have a much longer life than the regular concrete or sand-cement finishes.     

贵州省盘县畜禽良种繁育体系建设

畜禽品种是畜牧业发展的基础,随着传统畜牧业向现代畜牧业的逐步转变,必然要求建立与之相适应的畜禽良种繁育体系。根据盘县畜牧业发展实际情况和工作经验,提出畜禽良种繁育体系建立的一些观点。畜禽良种繁育体系建设既要引进良种,推广应用新技术,又要保护和应用地方品种。地方畜禽品种的保护是畜禽良种繁育体系建设的重要内容;地方畜禽品种保护是各级地方政府的责任,需要不断加大投入;地方畜禽品种保护县级宜采用建立保护区和保种场的办法。