The practice of separating grain mixtures with the use of the difference in the aerodynamic properties of their components has proved that the process of separating mixtures in the aspiration separator is the most promising one with regard to the improvement of quality and intensification of production. The authors have developed a new improved design of aspiration seed separators, in which the work process of separating seed material is performed with the use of vibration processes. In this seed material separator, the constant force air flow that acts on the sail members on the central pipe of the separator, when seeds are fed for processing, generates self-excited oscillations in the pipe, which produces centrifugal forces of inertia in the seed feeding system. As a result of the mentioned effect, the propelling force in the process under study substantially increases, accelerating the seeds of different fractions, which differ in their masses, to different velocities. The motion paths of the seed particles change accordingly, heavier particles moving closer to the vertical axis of the aspiration channel, which provides for increasing the efficiency of separation of the seeds of different fractions from each other. In this paper, a new mathematical model is developed for the motion of a seed mixture material particle process of vibration and aspiration separation has indicated that the separation of the motion paths of the medium and heavy fractions takes place within the range of 20 40 mm; the flying speed of the particles is equal to 3.2 8.0 m s 1, respectively; and their acceleration is equal to 1.8 3.3 m s 2, which provides the necessary conditions for the accurate and high quality separation into the required fractions. In view of the found differences between the kinematic characteristics of the separated fractions of the grain mixture, the diameter of the pipeline for the medium fraction is to be within the range of 90 100 mm, for the heavy fraction 50 70 mm.

Theory of grain mixture particle motion during aspiration separation

The yield loss during the process of harvesting is a great challenge in rice production. A suitable harvesting time and harvesting method can help to reduce the yield losses of rice, and decisions about the harvest date have important implications for labor management as well as for agricultural machinery scheduling. Nonetheless, the comprehensive composition of timeliness harvesting loss (THL) and its changing rules for different harvesting methods remain poorly understood. The objective of this study was to determine the effect of harvest date and mechanical harvesting methods on grain dry matter timeliness loss (GDMTL) and mechanical timeliness losses (MTL) of rice in the cold region. To this end, the field experiment was conducted from 45 days after heading (45 DAH) to 59 days after heading (59 DAH), adopting a full-feeding and semi-feeding combine harvester (FCH and SCH) from 2019 to 2020. The results showed that harvest date had a significant effect on GDMTL and four kinds of MTL including header timeliness loss (HTL), cleaning timeliness loss (CTL), un-threshed timeliness loss (UTTL), and entrainment timeliness loss (ETL, only under FCH). With the prolonged harvest date, the HTL and CTL increased and the UTTL and ETL decreased, which ranged from 0.15–0.31%, 0.36–0.67%, 0.72–0.18%, and 0.69–0.31%, respectively for FCH. For SCH, the variation range of HTL, CTL, and UTTL was 0.41–0.59%, 0.66–0.98%, and 0.64–0.21%, respectively. The GDMTL increased first and then decreased, ranging from 2.84–0.87%. The mechanical harvesting methods had no significant effect on the GDMTL of rice, but the MTL could be large between FCH and SCH. In general, optimal harvest period was 52 DAH~53 DAH for both harvesting methods, which exhibited the highest yield and the lowest loss, i.e., 9269.3 kg/hm2 and 1.70%, respectively, and the mechanical operating mode on different harvest dates was recommended to minimize the mechanical loss. The optimal harvest date for rice in a cold region ensured both quality and quantity for mechanized harvesting, and provided a reference for the reasonable allocation of operating harvesters in the harvesting season.

https://www.mdpi.com/2071-1050/13/11/6345/pdf

Timeliness Harvesting Loss of Rice in Cold Region under Different Mechanical Harvesting Methods

Forestry workers are exposed to vibrations from chainsaws which usually are not taken into consideration from the negative impact point of view on their health. However, in time, these vibrations could cause trepidation disease which will affect the worker neuro-muscular and locomotory apparatus. One mean to mitigate the vibrations impact is to measure and determine the worker’s exposure level to vibrations during worktime and to dispose the proper measures to reduce their negative impact. Within this paper will be presented experimental results obtained for vibration data recorded on a chainsaw during wood cutting in real life conditions. The equivalent vibration was measured at both front and end handles level and the biggest value was used for calculation of the human exposure level.

/pdf/evaluation-of-hand-transmitted-chainsaw-vibrations-during-138noc4jzz.pdf

Evaluation of hand transmitted chainsaw vibrations during wood cutting

The effect of harvest date on yield loss of long and short-grain rice cultivars (Oryza sativa L.) in Northeast China

A brush cutter is the most frequently used equipment for tending young forests. When cutting unwanted vegetation, the operator is exposed to various harmful factors, such as: a forced body position, noise, vibrations and exhaust emissions. In this study, the impact of cutting attachment type on the noise level during tending of young pine stands was examined. The attachments used during the tests included: a wire head and cutting blades with 2, 3 and 24 cutting teeth. The research was carried out on 2–3 year old Scots pine plantations covered with three types of vegetation: herbaceous, mixed and woody. It was proven that the the wire head was the device that generated the highest level of noise. In the case of cutting blades, the number of cutting teeth was the important factor. The greater the number of teeth in the cutting blades, the lower the noise level the device produced. There was no significant influence of vegetation type on noise emission level. Based on the results, in order to minimize operators’ exposure to noise, the use of wire cutting attachment should be limited.

/pdf/influence-of-cutting-attachment-on-noise-level-emitted-by-2w435nfpcf.pdf

Influence of Cutting Attachment on Noise Level Emitted by Brush Cutter during Tending of Young Forests

Noise is one of the priority issues of environment, especially in crowded urban zones. A low level of acoustic pollution leads to the environmental and consumer health protection satisfaction level and thus increases the quality of marketed products. The Directive 2000/14/EC it requires manufacturers to apply to each equipment introduced on market the guaranteed value of the acoustic power, in this respect the user being more and more informed in order to choose some reliable products with low noise level and reduced vibrations. The paper consists in determination of the acoustic power level, respectively the vibrations transmitted to the user by a brush cutter, in various functioning regimes.

Comparative Analysis of the Noise and Vibration Transmitted to the Operator by a Brush Cutter

The foreign bodies located in the grain mass have physical and morphological properties that distinguish them from the basic culture, and which are used in manufacturing the separating equipment. The experts’ attention has been drawn by the study of phenomena, which influence the process of separating impurities, aiming at a maximum reduction of impurities from the grain matter. Cereal and industrial plant seed pre-cleaning and cleaning, prior to their storage or processing, is a complex technological process that includes a multitude of constructive types for technical equipment designed to separate and remove existing impurities in the seed mass, which are based on various separation principles. Impurities in the seed mass are also different from the main crop seeds (grain seeds or industrial plants) in terms of aerodynamic properties. This paper presents some theoretical aspects regarding the separation of seed mixtures based on the aerodynamic principle (resistance of the seed mass layer to the passage of air, seed floating capacity, air stream working velocities, total air flow rate), which were the basis for the development of a new type of aeration cleaning separator SCA 5 for seed mixtures cleaning and sorting. The advantages of using this equipment in the process of precleaning/cleaning cereal and industrial plant seeds are also mentioned.

/pdf/considerations-on-technical-equipment-used-for-cleaning-and-2xknsnvpki.pdf

Considerations on technical equipment used for cleaning and sorting seed mixtures based on aerodynamic principle

Food losses in primary cereal production. a review

The paper presents the scheme of dynamic calculation of vibrating separator endowed with free vibrating plate and the author contributions concerning the determination of the movement of an intensive cleaner separator endowed with non balanced vibration generating systems. Also there are mentioned the advantages of electrical motovibrators utilisation for driving the vibrating sieves of technical equipment used for cereal cleaning in view of their processing.

Theoretical contributions to the drive of cereal cleaning technical equipment endowed with non balanced vibration generating systems.

The paper presents experimental research of qualitative indexes of impurities separation out of grain seeds for equipment using combined principles of separation (according to specific mass and aerodynamic properties of seeds). The experimental installation used was composed of a gravity separator with a mechanical shaker with unbalanced masses (mounted on the platform working surface) and an aspiration installation with a fan. The experimental research has aimed at quantitative and qualitative influence on separation quality index of the following operating parameters: material flow rate of the shaking separator, air flow of aspiration installation, tilting work surface, work surface oscillation amplitude. Based on the data obtained by the measurements and qualitative indicators the separating process indexes have been determined, namely: degree of impurities separation, degree of good seed loss, as well as the index of technological effect for different types of combinations of separation installation parameters.

https://tf.llu.lv/conference/proceedings2012/Papers/002_Bracacescu_C.pdf

Experimental researches on influence of functional parameters of gravity separator on quality indicators of separation process with application on cleaning of wheat seeds

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