Cosine response of pyranometers – Measurements at Pune

Among the various characteristics that determine the overall accuracy and performance of a pyranometer, the strict adherence to the cosine law is an important one. But this cosine response is difficult to realize and to correct for, The cosine response of various types of pyranormeters available at Pune was determined on the optical set up in Central Radiation Laboratory. The results of these studies are presented briefly.

Cosine response of an Indian pyranometer

ABSTRACT .The performance of a pyranometer depends on various characteristics like spectral response, linearity of output. temperature coefficient and dir~tional response" The departure from the cosine law is one of the most difficult to correct for and even to determine individually" The Central Radiation Laboratory has carried out the determination of cosine error at Pune. The results of such a measurement on an Indian made thermoelectric pyranometer are IX"esented and discussed"

The Similarity of Essay Examination Results using Preprocessing Text Mining with Cosine Similarity and Nazief-Adriani Algorithms

Exams are one way to measure the level of students' ability to participate in learning. One type of exam given to students is the essay type. This study focuses on making automatic assessments for essay-type exams using cosine similarity. This method has several stages such as folding Case, tokenizing, filtering, stemming, analyzing, weighing of words in documents with cosine similarity. The stemming process uses the Nazief & Adriani algorithm. The results of this study are to conclude that the choice of words that are considered as keywords in the answer key greatly affects the results of the system's assessment. This is evidenced by testing applying the cosine law of 89.5%. However, there are several types of questions that are significantly different because there are unique characters in the database and answer keys that do not contain keywords that match the correct answer.

TESTING THE HYPOTHESIS OF THE COSINE DISTRIBUTION OF STRESSES IN THE SHAFT-HOLE CONTACT

One of the most common connection types in mechanical engineering and construction is the shaft-hole connection. The mechanical stresses caused by its loading are distributed in the contact zone of the loaded parts of the joint. In some cases, they can lead to destruction. Therefore, while designing, it is important to analyze the mechanical stresses in the contact zone. Traditionally, calculations assume that the contact stresses are distributed according to the cosine law. However, this is not entirely true, especially with diff erent shaft and hole diameters. The authors examined theoretical studies of the contact zone of the shaft and the hole (including the cases of diff erent diameters) and the stress distribution in the contact zone. Based on the studies, they performed numerical calculations in the APMWinMachine environment to determine the stresses in the volume of the shaft and the plate with a hole when loading the shaft-hole connection. The analyses were performed for the two-dimensional case by the fi nite element method in the APMStructure program. The results show that when the diameters in the connection are equal, the stress distribution is close to the cosine law. In this case, only one stress raiser occurs in the contact zone, which is located on the line of action of the loading force. However, if there is a slight discrepancy in the shaft and hole diameters, there are three stress raisers in which the connection may break – the central zone and two side zones. The angular distance between them can be determined based on the known theoretical formulas. The authors made an experiment with a plexiglass model, which qualitatively confi rmed the correctness of the analysis performed.

Design and Evaluation of Tea-Plucking Machine for Improving Quality of Tea

Tea harvesting has always been tedious work. Tea harvesting mechanization is still incomplete in most tea-planting areas. To improve the mechanization of tea plucking, this article introduces a self-propelled track-type tea-plucking machine which mainly consists of a track chassis, an elevator system, a cutting system, and a transmission system. In this article, the structure and functions of the main parts of the self-propelled tea-plucking machine are introduced in detail. Additionally, the rigid body motion model was established. Next, orthogonal experiments (the factors were travel speed and the speed ratio of cutting to traveling) were conducted with three factor levels, and to choose the optimal factor level combination, fuzzy synthesize evaluation was conducted on the results of the orthogonal experiments. The motion model showing that the cutter moves in a cosine law and that the inertia force of the drive shaft and blades also move in a cosine law while working. The experiment reveals that (1) both travel speed and speed ratio of cutting to traveling have a significant effect on the quality (integrity rate, unpicking rate, stubble unevenness) of plucked tea leaves, and (2) the interaction affects only the integrity rate. The fuzzy synthesize evaluation indicates that the optimal factors are as follows: the cutting speed is 0.3 m/s, and the speed ratio of cutting to traveling is 1.0. With this set of parameters, the plucking integrity increased by 20% compared with Japan’s ride-on-type tea-plucking machine. This research made considerable progress in the mechanization of tea plucking, which reduces the cost for employing pickers, enhances the earnings of farmers by improving the quality and price of tea, and supports the sustainable development of tea industry. Keywords: Agricultural machinery, Experiment, Fuzzy synthesize evaluation, Harvest, Hydraulic, Tea.

Modelling of the conjugate natural convection in a closed system with the radiant heating source radiant energy distribution by Lambert’s cosine law

Various types of emitters are often used as energy sources in real engineering systems and technological processes. Investigations of heat transfer basic laws in such systems are of interest. We conducted mathematical modelling of conjugate heat transfer in a closed rectangular cavity under conditions of radiant energy source operating. The 2-D problem of conjugate natural convection in vorticity stream function-temperature dimensionless variables has been numerically solved by means of the finite difference method. Radiant energy distribution along the gas-wall interfaces was set by Lamberts? cosine law. We obtained fields of temperature and stream functions in a wide range of governing parameters (Rayleigh number 104 ? Ra ? 106, the length of radiant heating source 0.15 ? D ? 0.6). Then we analyzed how heat retaining properties of finite thickness heat conducting walls made of different materials affect the heat transfer intensity. Differential characteristics distribution showed significant non-uniformity and non-stationarity of the conjugate heat transfer process under study.