Jukka Ahokas

Instrumentation, measurement and performance of three air quality measurement systems for dairy buildings

Recent interest in global warming has led to the monitoring of operations such as dairy production that emit pollutants into the atmosphere. However, monitoring systems for indoor air quality in dairy buildings are still uncommon due to high costs involved in designing systems that can withstand high moisture, dust, corrosive gases, and varying temperatures. For studying the performance of measurement systems for dairy buildings, three different air quality measuring systems were built using both affordable and expensive sensors. The measurement systems were 1) a stationary system for longer period on-site measurements, 2) a wireless stationary system for off-site measurement, and 3) a mobile system for periodic air quality measurement. The instrumentation, measurement procedures, and performance of these systems are presented in this article. Spatial air quality survey showed high variation in microclimate conditions in the dairy building. Average deviation of sensors from the true value in the different measurement systems was 1.1°C for temperature, 3.6% for relative humidity, 450 ppm for carbon dioxide, 0.5 m/s for velocity, and 1 ppm for ammonia. Affordable sensors in the systems gave reasonably accurate readings when carefully calibrated. The single most practical location for installing air quality measurement systems was directly above the dairy cows in the center of the dairy building.

Contactless measurement of cow behavior in a milking robot

We have worked on automatically measuring the behavior of dairy cows during automatic milking. A milking robot offers a unique possibility for a dynamic measurement of physical data. Four strain gauge scales were installed into a milking robot in order to measure the weight of each leg separately, and a laser distance sensor was placed next to the robot in order to measure the radial movement of the cow’s body surface. The data were collected into a PC. Three video cameras were installed to observe the system, and the data were recorded digitally. From the data, the dynamic weight or load of each leg and the respiration rate of a cow could be measured. Different stages of milking were observed, and the changes in behavior during milking were analyzed. The acquired information could be used to judge a cow’s restlessness and welfare—for example, leg health and stress.

Dynamic Behaviour of a Tractor-trailer Combination during Braking

Both the theoretical and practical aspects of braking in a tractor and single axle trailer combination were examined using appropriate tests that also measured other behavioural characteristics of the combination. The results showed that braking distance or deceleration can be calculated accurately but the actual braking behaviour on icy roads can currently be determined only by testing. The results also showed that the test standards for agricultural trailer brakes can give erroneous results when single axle trailers are used. Future standardisation work in single axle trailers should employ modified test procedures. In standards and legislation, braking performance is often determined by the stopping distance or deceleration value. For brake performance the braking ratio can be calculated from the axle load and deceleration. This value gives a better figure for the torque capacity of the trailer brakes and in brake performance tests should be used instead of stopping distance or deceleration values.

Image Based Separation of Dairy Cows for Automatic Lameness Detection with a Real Time Vision System

Automation of lameness detection with vision techniques has a high potential to improve the early recognition of lame cows and would have a positive impact on time efficient herd management. In order to get individual information about gait features from cows passing a corridor in row e. g. after leaving the milking parlour an automatic separation of cows in a sequence is necessary. The presented results are based on video recordings done on farm, where cows walk from the milking parlour after milking through a corridor in row of 10 to 20 animals. To cope with problems such as stopping for a while in front of the camera, overlap of cows, non-uniform time interval between cows, etc. an algorithm for cow separation is proposed based on local image filtering and statistical analysis of binary images frame by frame. Filters to enhance horizontal and vertical edges in an image are utilized for shadow and background reduction. Binarization on filtered images is made by using statistical analysis. The column-based summation of binarized images related to a threshold is used to decide when the next cow in a row is detected after another has passed already. First results show 95% correct cow separation.

Parallel plate heat exchanger for heat energy recovery in a farm grain dryer

ABSTRACT One of the methods with the most potential to reduce energy consumption in grain drying is heat recovery from the dryer exhaust air. A parallel plate heat exchanger to recover heat energy from the exhaust air of a recirculating batch grain dryer was examined by theoretical assessments as well as by measurements in a scaled-down research dryer and experimental heat exchanger. In addition to the heat transfer performance, the operability in dusty conditions was investigated. Finally, the optimization of the heat exchanger was introduced by the aid of the calculation models and practical measurement. The heat exchanger performed satisfactorily, providing an average energy saving of approximately 18%. A significant improvement in the performance could be achieved by increasing the air velocity. No severe dust accumulation was observed, and a heat exchanger of this type could provide remarkable energy saving possibilities in grain drying. Further tests are necessary to ensure the operability in long-term use.

The mobility of small and medium sized combine harvesters in muddy conditions.

The objective of this study was to investigate the factors which have an effect on the mobility of wheeled combine harvesters in difficult harvesting conditions. Test areas included wet clay soils, high organic matter soils and slippery clay soil slopes. In the experimental combine harvester, it was possible to change the wheel gauge in the rear, wheel sizes and the weight distribution. Radial, cross-ply and dual tyres were compared. In addition, a hydrostatic rear wheel drive system was included in the research programme. In most cases the high motion resistance of the rear tyres caused high slippage values at the front tyres. The most obvious improvements in the mobility of combines can be made through improvements to the rear axles. The wheel gauge in the rear axle should be exactly the same as in the front. Rear tyres with large diameter should be about half as wide as the front tyres and even the rear tyres should have a “V”-tread. By changing the rear axle construction and the tyre size, it was found possible to reduce resistance to motion by 30%. Large diameter tyres provide the most effective means of improving mobility of combines in soft conditions. Wide tyres with a wide contact area are likely to cause bulldozing effects when the bearing capacity of the topsoil is small.

Challenges of Bioenergy Analyses

Shortcomings in analyses of bioenergy systems may lead to unrealistic or overoptimistic expectations for replacing fossil energy with bioenergy. This paper addresses problems faced in our study.

Automatic Cow Health Measurement System in a Milking Robot

Milking robot offers a unique possibility for dynamic measurements of physiological data. We have worked on automatically measuring health of dairy cows during automatic milking. The measurement system consists of leg health measurement system and a respiration rate measurement. Four strain gauge scales were installed into a milking robot in order to measure the weight of each leg separately and a laser distance sensor was placed next to the robot in order to measure the radial movement of cow’s body surface. The sensors were connected to an amplifier and the data was collected into a PC using a dedicated computer program. Three video cameras were installed to observe the system and the data was recorded digitally. From the data the dynamic weight or load of each leg and the respiration rate of the cow can be measured. The average weight, the weight variation of each leg, the total weight, the number of kicks and steps, the frequency of kicks and the total time in the milking robot can be calculated. The data can be used for automatic detection of leg problems and it is highly probable that the symptoms of heat stress can be detected as increased respiration rate.

Microclimate and gas emissions in cold uninsulated dairy buildings

A measuring tower was built for continuous cattle house microclimate and gas emission measurements. The tower was made strong enough to be able to be left amongst the cows. The tower measured temperature, humidity and air velocity at three heights and carbon dioxide, ammonia and hydrogen sulfide at one height. The measuring system was situated in a cattle house in Eastern Finland. The first data showed that cows can get along in extreme cold conditions. The outside temperature of the cattle house was – 33 oC for several days with a corresponding inside temperature of -28 oC. One of the problems in the cattle house was with high moisture content. This would need a more efficient ventilation.