Search results

The purpose of this paper is to present the augmented reality (AR) eyeglass selection problem based on Neutrosophic MULTIMOORA method which is a very new multi-objective method.

The author evaluates five AR goggles according to six different criteria. Criteria have different weights and determined by analytic hierarchy process. The author used neutrosophic MULTIMOORA method in order to evaluate AR eyeglasses.

Five different AR eyeglasses were evaluated and the best one was selected according to six different criteria (benefit and non-benefit). According to Neutrosophic MULTIMOORA method, Sony AR eyeglass is selected as the best one. Neutrosophic MULTIMOORA method uses simple computational equations and it handles multi-objective decision making problems effectively.

Evaluating AR goggles by using the Neutrosophic MULTIMOORA method for the first time is the originality of this paper.

The purpose of this study is to design and manufacture a new remote center of motion (RCM) mechanism for use in laparoscopic surgical operations. In addition, obtaining the forward and inverse kinematic equations of the RCM mechanism and performing real-time position control with the Proportional–Integral–Derivative (PID) control method.

At the design stage, it is benefited from similar triangle rule. To obtain the kinematic equations in a simple way and facilitate control, two-fold displacement ratio is provided between the limbs where linear motion occurs. The rotation and displacement amounts required to move at the RCM point have been calculated by using the kinematic equations of the mechanism. Limb dimensions and motion limits are determined in the manner to avoid singularities and collisions. The x, y and z coordinates of the end effector have been defined as the reference point. Control of the mechanism was provided by PID control. To generate the user interface and control algorithm, MATLAB/Simulink real-time toolbox has been used. Four reference points were determined, control was performed and position error values were examined. MF634 Humusoft data acquisition card has been preferred to collect data from encoders.

A novel RCM mechanism has been designed and manufactured. Kinematic equations of this mechanism have been obtained. Position control of the cannula tip has been performed using PID control method for four different reference points. After settlement, maximum position error has been observed as 0.45 mm.

Structure of the designed mechanism is quite simple. Thus, costs are quite low. The operation area of the operator is widened by hanging the mechanism from the ceiling, so operational capability of health personnel is increasing. It helps to decrease the operation time and increase the success of the operation.

With this study, it is aimed to contribute to the literature by designing a new RCM mechanism. The rotation of the mechanism around the RCM point is provided by only one rotary motor, and the displacement of the RCM point in the vertical axis is provided by only one linear motor. The mechanism is also a surgical robot. The designed system is suitable for use in robot-assisted laparoscopic surgery in terms of maneuverability.

The aim of the study is to evaluate role of trade war between the United States and China on oil price. For this purpose, global oil price and US trade balance with China are selected as variables. In addition to this issue, monthly data of these variables for the periods between 1990 and 2019 are taken into consideration. In the evaluation process, both Engle–Granger cointegration and Toda–Yamamoto causality analysis are considered. The results of Engle–Granger cointegration analysis indicates that there is a ­relationship between trade war and oil prices. Nevertheless, according to the results of Toda–Yamamoto causality analysis, it is identified that trade war does not cause oil prices. While looking at these results, it is determined that trade war between the United States and China has an influence on the oil price changes. However, it is also understood that it is not the main factor of this volatility. Thus, it is recommended that in order to identify the main indicator of the oil price volatility, some different factors should also be taken into consideration.

The European states, which started the industrial revolution by making use of mechanical power, provided their agricultural development by producing new technology tools that will increase the production in the agricultural sector. The Ottoman Empire made many attempts to increase agricultural sector in the nineteenth century and implemented policies to increase production. In this direction, primitive agricultural tools were changed, and many encouraging steps were taken to adopt and spread modern technology in the country. As a result of the policies made, since the second half of the nineteenth century, the use of modern technology has increased in the provinces such as İzmir, Edirne and Adana and then in Konya and Ankara, since the railways reached the interior. Increasing accessibility to international markets with the development of commercial agriculture and railway construction are also important factors that encourage the use of machinery. When the use of machinery increased in the twentieth century, many machine companies opened dealers in the country and attempted to reach the inner parts of the country. With the increase in the use of modern agricultural technology, agricultural production has increased and provided significant benefits to the labor problem, especially in regions where commercial agriculture has developed. The effect of modern technology on the increase in production can be seen in the agricultural numbers in 1909–1914. When the agricultural census is taken into consideration, although the production areas did not increase, the production amount increased. However, the contribution of modern agricultural technology to production was still somewhat limited. The reason for this is that due to the high prices of agricultural machinery, small farm owners cannot supply these machines.

This paper aims to explain the influence of Standard Fire as per ISO 834 on the strength and microstructure properties of concrete specimens with different strength grade.

The strength grades of concrete considered for the experimental investigation were Fck20, Fck30, Fck40 and Fck50. The specimens were heated up to 1, 2, 3 and 4 h as per standard fire curve. Effect of elevated temperature on compressive and flexural behavior of specimens with various strength grades was examined. Effects of age of concrete, weight loss, surface characteristics and thermal crack pattern were also investigated.

Experimental investigation shows that strength grade, duration of exposure and age of concrete are the key parameters affecting the residual strength of concrete. For the beams exposed to 3 and 4 h of heating, the residual flexural strength was found to be so insignificant that the specimens were not able to even sustain their own weight. The loss in compressive and flexural strength of Fck50 concrete specimens heated up to 1 h were found to be 26.41 and 86.03 per cent of the original unheated concrete, respectively. The weight loss was found to be more for higher grade concrete specimens, and it was about 8.38 per cent for Fck50 concrete. Regression analysis was carried out to establish the empirical relation between residual strength and grade of concrete. Scanning electron microscopy and thermogravimetric analysis were carried out to examine the damage level of fire-affected concrete specimens.

Empirical relationship was developed to determine the residual strength of concrete exposed to elevate temperature, and this will be useful for design applications. This database may be useful for identifying member strength of reinforced beams subjected to various durations of heating so that suitable repair technique can be adopted from the available database. It will be useful to identify the proper grade of concrete with regard to fire endurance, in the case of concrete under compression or flexure.