Population growth in the last 20 years and also diversifying people's food needs have led to an increased demand for products obtained from animals raised on zootechnical farms. For maintaining in the profile market, by providing quality products at the lowest price, the combined feed factories were equipped with modern work equipment and installations to ensure a high degree of mechanization, automation and computerization of the activities performed. This had favourable consequences in achieving high productivity with low specific consumption. The technological flow carried out in a combined feed factory involves performing several activities, such as: supply, transport, grinding, mixing, granulation, cooling, packaging and storage. Thus, a very important activity in a combined feed factory is the transport of raw materials from warehouses to work facilities. To ensure proper functioning of work facilities and an increase of labor productivity, the implementation of automated control of conveyor belts is recommended. The experimental investigations were based on the achievement of an electronic device, through which the operation of magnetic rotation and proximity sensors was monitored. These types of sensors equip the automatic control devices for conveyor belts used in a combined feed factory. The electronic assembly realized in own conception allowed to determine with accuracy the values of the response times, as well as the distances required for automatic shutdown of the transport system. In case of overload, this automatic shutdown command is of major importance in order to avoid the destruction of the transport system. The obtained results demonstrate the functionality of the designed command and control system, as well as the need for its implementation to ensure automated monitoring of the transport of raw materials between the work facilities.
Persistent left superior vena cava (PLSVC) is a rare vascular congenital anomaly yet the most common for the thoracic venous system. Usually asymptomatic, PLSVC is commonly diagnosed when echocardiography or other cardiovascular imaging is performed. Due to venous drainage abnormality, PLSVC is frequently associated with other anomalies of the intrinsic heart’s conduction system, leading to tachy- or brady- arrhythmias. We present the case of a patient with 20 years history of supraventricular rhythm disorders diagnosed with isolated PLSVC. Furthermore, we discuss the diagnostic approach providing insights into four-dimensional echocardiography (4DE) evaluation for PLSVC diagnosis, assuming that there is a direct correlation between coronary sinus dilatation caused by abnormal venous return and supraventricular rhythm disorders. We highlight that correct understanding of the pathophysiology of PLSVC will lead to a reduction in unnecessary and potentially harmful testing, to a shorter diagnostic time and to a financial resource saving, as a whole.
Precision sowing importance, as a factor influencing the development of crops determined the specialists in the field to do sustained research to find ways to mechanize the sowing work with high precision, to ensure the number of plants per unit area, respectively, the necessary space for plant development. Increased precision of agricultural sowing machines has direct implications on the germination, emergence and development of plants. The paper presents researches on precision sowing machines, equipped with pneumatic distributors, these being the most used models, manufactured by foreign and Romanian companies. The purpose of the experimental research was: determining the influence of certain physical characteristics, as the seed form, MMB on sowing accuracy; establishing the way in which these characteristics influence the free fall speed of the seeds from the distribution apparatus to the ground, taking into consideration the possibility of increasing this parameter, in order to reduce the travel times of the distance to the ground; determining the floating speed of seeds from several crops, this being an important parameter, which influences the design and adjustments of the sowing machines. The laboratory tests were performed on a stand with fixed sowing body. The seed distribution disk was driven with rotational speeds, corresponding to the working conditions, without slipping. Within the experimental laboratory researches, measurements were made in order to determine the uniformity of distribution of seeds on the row. Following the tests performed, it was found that the values of this parameter falls within the requirements imposed for sowing hoeing plants. The experimental results allow the elaboration of useful recommendations for farmers using these technical equipments.
The use of electronic regulators, in order to correlate the working parameters at sprinkling machines, requires a study to assess the performances of the regulation process in working conditions. Given that the parameters to be correlated are physical sizes, the equipment must be fitted with appropriate sensors to perform the conversion into electrical sizes. Processing the input information, present in the form of electrical voltages, can be achieved only by a specialized circuit of comparator type. To operate properly the liquid flow control valve, this circuit will have to generate different commands in the form of electrical signals. Having low values, these signals are not at the required level to operate the electric motor used for actuating the control valve. Therefore, it is necessary to amplify them to an appropriate level by a power amplifier. The amplifier must be able to put the motor rotor in short-circuit mode with the cancellation of each adjustment command. This mode of operation ensures strong braking and stoppage almost instantaneously of the rotor. This fact has favourable consequences on accuracy of flow adjustment. For optimum operation of the equipment, the design of these circuits was done so as to ensure a maximum sensitivity by eliminating self-oscillating work regimes. Experiments were performed simulating on adequate stands the real working process of a sprayer, equipped with such a regulator. Testing in laboratory conditions has the following purposes: checking the functioning of some important electronic circuits, which are components of the adjusting system; establishing the performances of the adjustment system, from the point of the quality of the adjusting process. Analysis of the obtained results from the tests demonstrates that the hysteresis of the comparator circuit is10 mV, in accordance with the setting, ensuring a good sensitivity during operation and also the elimination of the over-adjustment phenomenon. Amplifying the signals at the 9 V value, the power amplifier ensures a proper reversal of the sense of rotation of the actuating electric motor and putting in short-circuit mode for its quick stop. Due to the correct operation of the designed circuits, the adjustment function is performed correctly, the deviation from the prescribed adjustment report being just 0.2 %.
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