Should I study or should I go (to sleep)? The influence of test schedule on the sleep behavior of undergraduates and its association with performance

Sleep is crucial for college students’ well-being. Although recommended sleep duration is between 7–9 hours per day, many students do not sleep that much. Scholar demands are among the causes of observed sleep deprivation in youth. We explored the influence of having a school test on previous night sleep in first-year students and the association of sleep duration and test performance. We ran two surveys in freshman students of the Universidad de la República, Montevideo, Uruguay: 1) 97 students of the School of Sciences who took the test at the same time; and 2) 252 School of Psychology students who took the test in four successive shifts. More than 1/2 of the participants (survey #1) and almost 1/3 (survey #2) reported short regular sleep duration (< 7h). In both samples, the sleep duration of the night before the test was reduced with respect to regular nights (survey #1: 2.1 ± 0.2 h, p < 0.001; survey #2: between 1.7 ± 0.4 h and 3.6 ± 0.3 h, all p < 0.001), with more than 10% of the students who did not sleep at all. In survey 2, sleep duration increased in later shifts (F (3,248) = 4.6, p = 0.004). Using logit regressions, we confirmed that sleep duration was positively related to test scores in both samples (survey #1: exp B = 1.15, p < 0.001; pseudo-R2 = 0.38; survey #2: exp B = 1.03, p < 0.001; pseudo-R2 = 0.25). Delaying test start time may prevent the reduction in sleep duration, which may also improve school performance. In addition, educational policies should include information for students about the impact of sleep on learning and of the consequences of reduced sleep duration.

High-Load Titanium Drilling Using an Accurate Robotic Machining System

Robotic drilling systems have been used in the manufacture of large aerospace components for a number of years. Systems have been developed by several systems integrators in order to accurately drill materials from CFRP to Titanium. These systems, however, have been unable to achieve large diameter holes in Titanium due to reduced structural stiffness and end effector capabilities. Typically, large holes are either drilled using large cartesian CNC-controlled machines or drilled using automated drilling units (ADU). However, there is a pull from aerospace OEMS to move away from large monolithic machines, in favour of flexible robotic system. Flexible robotic systems provide a number of benefits for large structure assembly. The following report primarily outlines drilling trials conducted on the Accurate Robotic Machining System, during which holes from 25 mm to 32 mm ID were drilled in titanium implementing an empirical test schedule. Additionally, a discussion on the benefits of drilling large diameter holes using flexible robotic platforms.

Improving the test methodology of design piles on a construction site

Reliable solutions for the design of tall buildings with pile foundations depend on the correctness of the load-bearing capacity. In some cases, you need to know that it is impossible to determine the ability on the side surface and under the sole. To do this, it is proposed to develop a special technique that combines tests to remove and pull out and educate the nature of the downloads (static or kinematic).Тhe publication proposes a method of testing piles in the field, which simulates the processes that accompany the interaction of the pile with the soil base in real situations of operation of the technical object: for example, emergency soaking of soils when there is no time for stabilization deformations under load from a building or structure. It is shown that the value of friction on the side surface of the piles significantly depends on the nature of the loads. The analyzed results of the test schedule allow to separate these two components in the case when unloading is carried out continuously and the beginning of the pile movement in the opposite direction gives the value of soil resistance on the side floor. This simulates the real behavior of the pile at the base of the building, because in real objects there is no time for stabilization.It is offered to carry out tests of piles before loading which causes continuous indentation of piles, and division into components - bearing capacity on lateral surface Fdf and bearing capacity under the sole of the pile FdR will allow to accumulate the calculated soil supports in the respective zones, which makes it possible to create tables «R» and «f» for soil conditions of Ukraine.Taking into account the peculiarities of the construction of the pile test schedule and the proposed approaches will allow to correctly determine the components used in determining the bearing capacity of the pile. The accumulation of test results in the future will clarify the calculated soil supports of Ukraine. Reliable values of the calculated resistances will reduce the amount of static tests, which are time consuming and expensive.

Influence of chosen technical constraints on stability of 3D geological model-based schedule in a complex longwall operation

In Polish underground mining digital 3D geological models and mine structure models are becoming popular as an aid in creating design and schedules of mine workings. Article highlights development made in generating and optimizing mining operations. Having created a model it is possible to test schedule scenarios using a number of constraints. One of the constraint limiting coalmines is ventilation, which may be magnified by high content of methane in coal deposits. In this article two methods of introducing ventilation constraints have been presented. One limits number of longwall shearers working simultaneously in excavations ventilated by the shaft. The other limits tonnage of coal which can be extracted in each ventilation zone. Scenarios governed by the second method turned out to result in more stable exploitation than a base scenario. More precise calculations are possible if a model contains an accurate prognosis of methane emissions that would be caused by extraction of the coal deposit. The aim of the paper is to present possibilities of analysing and upgrading mining operations with the help of digital solutions.