A manipulator size optimization method based on dexterous workspace volume

Background: Manipulators for robots are required to have high manipulability for adaptability in different tasks. However, general methods for designing manipulators with high manipulability are deficient. Here, aiming at improving the manipulability of the six degrees-of-freedom (DOF) manipulator, a method for optimizing structure size parameters based on the dexterous workspace volume is proposed. Methods: Firstly, the kinematic analysis of the manipulator is performed. Then, the manipulability of the single working point of the manipulator is judged based on reachability in different postures. The workspace of the manipulator is discretized to obtain the volume of the overall dexterous workspace. By taking the maximum volume of the dexterous workspace as the optimization goal, Genetic Algorithm (GA) is used to optimize the structure size parameters to achieve optimal manipulability. AUBO 6-DOF manipulator is defined and analyzed as an example. Results: The optimization results indicate that the dexterous workspace of the manipulator expands in volume and its manipulability is improved. The validity of the proposed optimization method is verified by comparing the distribution of dexterous workspace of the manipulator. Conclusions: This article proposes an optimization method for the structure size parameters of a 6-DOF manipulator, which can be implemented to improving the manipulability of the manipulator.

Water-air ejector with conical-cylindrical mixing chamber

In the paper, the hydrodynamics of the liquid-gas mixture in the mixing chamber of the ejectors at different spatial positions was analyzed and the comparative study of such ejectors was carried out. It was found that a more ordered mode of movement of the mixture in the mixing chamber is created as a result of the coincidence of the velocity vector of liquid drops and the direction of gravity in the vertical position of the ejectors. This leads to increasing the volume entrainment ratio almost twice. The analysis of the liquid-gas mixture flow in the mixing chamber, evaluation calculations and research allowed to develop and to patent a jet apparatus with a conical-cylindrical (combined) mixing chamber. It was also found that for such ejectors, the volume entrainment ratio is 15–55% higher than for a jet apparatus with a cylindrical mixing chamber due to the reduction of the resistance of the passive flow into the mixing chamber and prevention of the formation of reverse-circulating flows. A study has been conducted on liquid-gas ejectors in the range of the main geometric parameter m (ratio of the mixing chamber area to the nozzle area) 9.4–126.5, which allowed to establish its rational values at which the maximum volume entrainment ratio is achieved (m = 25–40).

Cost analysis of manual bund shaping in paddy fields: Economical and physiological

Bund shaping is one of the essential operations in preparing a paddy transplanting field. This operation is undertaken manually by spades in a traditional way as this has not been mechanised thus far. Therefore, this study was conducted to expose this operation by evaluating the economic, as well as physiological, cost involved in the bund shaping. For the economic cost, the study was conducted in nine different districts of Assam (India). The bund length for the estimated area was measured and estimated for one ha of land. The average rate of manual bund shaping was also measured to calculate the cost involved in this operation. Moreover, for the physiological cost, ten experienced subjects were calibrated and measured for their maximum aerobic capacity by sub-maximal exercise in laboratory condition. Furthermore, the heart rate was measured during the manual bund shaping and was then correlated with the calibrated data. It was found that the average required bund shaping length per ha was 3 669 m which was associated with a cost of 2 062.8 rupees. It was found that the bund shaping consumed 76.96% of the maximum volume of the oxygen consumption capacity of the subjects; however, the energy expenditure rate with respect to time and bund length were 7.37 kcal·min^–1 and 4.33 kcal·m^–1, respectively. Hence, bund shaping in a paddy field comes under a severe workload category which emphasises the need of mechanisation for the bund shaping operation.

EVALUATION OF CUMULATIVE PROPERTIES OF THE COMPLEX TOOL Z-88

This present work is devoted to the study of cumulative properties of the complex means Z-88. The studies were carried out on intact mongrel laboratory rats that had previously passed quarantine measures for 12 days. Two equivalent groups were created. The animals of the experimental group were injected intramuscularly in the thigh area with Z-88, and the control group was similarly injected with 0.9% sterile sodium chloride solution. On the first day of the experiment, the rats were injected with test drugs at a dose of 0.5 ml per animal, which was 1/10 of the maximum volume used in experiments to determine the parameters of acute toxicity. Both Z-88 and sterile saline solution were administered once a day throughout the experiment. Z-88 was administered once a day throughout the experiment. Starting from the fifth day, in every subsequent four days, the dose of the drug was increased by 1.5 times. The duration of the experiment was 24 days. During the experimental period of visible changes on the part of the studied indicators.

Squirrel-Cage Fan System Optimization and Flow Field Prediction Using Parallel Filling Criterion and Surrogate Model

In this study, the blade shape of the squirrel-cage fan system inside the range hood was optimized using the surrogate model to improve the maximum volume flow rate. The influence of computational fluid dynamics (CFD) noise was concerned. The regression Kriging model (RKM) was used as a surrogate model to reflect the relationship between the design parameters of the blade and the volume flow rate. The parallel filling criterion after re-interpolation was used to improve the optimization efficiency further and ensure global optimization. Through experimental verification, we found that the relative error between the volume flow rate of the optimal sample of RKM and the experiment was only 0.4%. Compared with the prototype, the maximum volume flow rate of the optimal sample of RKM was increased by 2.9%, and the efficiency under the corresponding working conditions was increased by 2%. RKM was used to predict the velocity field of the volute and impeller exit section to explore the feasibility of the RKM in the flow field prediction. Research shows that the RKM cannot accurately predict the velocity of each grid on the cross-section. Still, it can accurately predict the changing trend of the velocity.

Fast satellite selection algorithm for GNSS multisystems based on the Sherman-Morrison formula

The usage efficiency of GNSS multisystem observation data can be greatly improved by applying rational satellite selection algorithms. Such algorithms can also improve the real-time reliability and accuracy of navigation. By combining the Sherman-Morrison formula and singular value decomposition (SVD), a smaller geometric dilution of precision (GDOP) value method with increasing number of visible satellites is proposed. Moreover, by combining this smaller GDOP value method with the maximum volume of tetrahedron method, a new rapid satellite selection algorithm based on the Sherman-Morrison formula for GNSS multisystems is proposed. The basic idea of the algorithm is as follows: first, the maximum volume of tetrahedron method is used to obtain four initial reference satellites; then, the visible satellites are co-selected by using the smaller GDOP value method to reduce the GDOP value and improve the accuracy of the overall algorithm. By setting a reasonable precise threshold, the satellite selection algorithm can be autonomously run without intervention. The experimental results based on measured data indicate that (1) the GDOP values in most epochs over the whole period obtained with the satellite selection algorithm based on the Sherman-Morrison formula are less than 2. Furthermore, compared with the optimal estimation results of the GDOP for all visible satellites, the results of this algorithm can meet the requirements of high-precision navigation and positioning when the corresponding number of selected satellites reaches 13. Moreover, as the number of selected satellites continues to increase, the calculation time increases, but the decrease in the GDOP value is not obvious. (2) The algorithm includes an adaptive function based on the end indicator of the satellite selection calculation and the reasonable threshold. When the reasonable precise threshold is set to 0.01, the selected number of satellites in most epochs is less than 13. Furthermore, when the number of selected satellites reaches 13, the GDOP value is less than 2, and the corresponding probability is 93.54%. These findings verify that the proposed satellite selection algorithm based on the Sherman-Morrison formula provides autonomous functionality and high-accuracy results.

Place of regorafenib in treatment of patients with metastatic colorectal cancer: when are all options exhausted? Or in third line?

The use of regorafenib in the treatment of patients with metastatic colorectal cancer divides Russian and foreign oncologists into two camps. Many specialists postpone its appointment until a situation where all other options for systemic therapy have been exhausted, and the physical condition is close to unsatisfactory, and the metastatic process reaches its maximum volume. The position of oncologists adhering to such positions is based on a small number of objective answers and low survival rates without signs of progression of the process, with evidence of a more effective re-prescription of chemotherapy and targeted drugs already used in the treatment of this patient. On the other hand, an analysis of the world literature on regorafenib and options for the third line of therapy for metastatic colorectal cancer shows the ambiguity of the above approach and the potential of the drug in terms of improving the patient’s prospects by overcoming the resistance of the tumor mass to already used drugs and the ability to provide the patient with the so-called chemotherapeutic holiday.

Granulometric Parameters of Solid Blueberry Fertilizers and Their Suitability for Precision Fertilization

For precise fertilization of blueberry plants, it is technologically the easiest and most suitable option to use a volumetric filling, for which it can be presumed that it is possible to precisely dose the fertilizer for each plant by grams. For setting up a volumetric filler, it is necessary to know parameters such as the size of the fertilizer particles and their bulk density. The aim of this research is to determine the granulometric parameters and their effect, which is done by measuring up three different fertilizers (SQM Qrop K, Memon Siforga, Substral): width, height, and length of 100 randomly selected fertilizer particles as well as the volumes and weights of 100 particles in 10 repetitions. According to the measurements, the average diameters of fertilizer particles were found as well as the average mass, volumes, and bulk density. A Mahr Digital Caliper 16EWRi 0–150 mm was used to measure the diameters of the fertilizer granules. A Yxlon FF35 computer tomograph was used to accurately scan particles. The analytical scale, Kern ABJ 220-4NM, was used to determine mass. The volumes were measured, using measuring glasses, with one having a maximum volume of 10 mL in 0.2 mL increments and another having a maximum volume of 100 mL in 1 mL increments. Descriptive statistics analysis was performed in Microsoft Excel. It turned out that the average diameters (3.68 vs. 3.64 vs. 4.29 mm) and bulk densities (0.928 vs. 0.631 vs. 0.824 g cm−3) of the three fertilizers differed far from each other, meaning that the given volume could be filled with different amounts of fertilizer. Equations between mass and weight were formed according to the measurements. As a result, it was found that a volumetric filler can be used for fertilizing blueberry plants precisely, but it demands adjusting the filler each time in the situation, which is defined by the variety of blueberry plants: their age, size, and health.

Profile Of Maximum Volume Level Of Takraw Athlete State High School Of Sports Ability (SMANKO) Bengkulu Province

The purpose of this study was to determine the maximum oxygen uptake of athletesSepak takrawSports Talent State High School (SMANKO) Bengkulu Province. This study is a descriptive study. Collect data using a survey method with tests and measurements. This instrument is used to measure the maximum VO2 test using the Bleep test. The subject of this research is AthleteSepak takrawThe State High School of Sports Talent (SMANKO) of Bengkulu Province totaled 11 athletes. The data analysis technique used in this research is quantitative description analysis presented in percentage form. The conclusion that can be drawn is that the athletes' maximum oxygen uptake is as follows: In the very good category there are 0 athletes (0%), in the good category there are 0 athletes (0%), the moderate category there are 11 athletes (100%), in the poor category there are 0 athletes (0%) and very bad category there are 0 athletes (0%)