A comparison of methods for the long-term harness-based attachment of radio-transmitters to juvenile Japanese quail (Coturnix japonica)

Background While the period from fledging through first breeding for waterbird species such as terns (e.g., genus Sterna, Sternula) is of great interest to researchers and conservationists, this period remains understudied due in large part to the difficulty of marking growing juveniles with radio transmitters that remain attached for extended periods. Methods In an effort to facilitate such research, we examined the impact of various combinations of harness types (backpack, leg-loop, and 3D-printed harnesses), harness materials (Automotive ribbon, Elastic cord, and PFTE ribbon), and transmitter types (center-weighted and rear-weighted) on a surrogate for juvenile terns, 28-day-old Japanese quail (Coturnix japonica; selected due to similarities in adult mass and downy feathering of juveniles), in a 30-day experiment. We monitored for abrasion at points of contact and tag gap issues via daily exams while also recording mass and wing cord as indices of growth. This study was designed to serve as an initial examination of the impacts of marking on the growth and development of young birds and does not account for any impacts of tags on movement or behavior. Results While we found that treatment (the specific combination of the transmitter type, harness type, and harness material) had no impact on bird growth relative to unmarked control birds (P ≥ 0.05), we did observe differences in abrasion and tag gap between treatments (P ≤ 0.05). Our results suggest that leg-loop harnesses constructed from elastic cord and backpack harnesses from PFTE ribbon are suitable options for long-term attachment to growing juveniles. Conversely, we found that automotive ribbon led to extensive abrasion with these small-bodied birds, and that elastic cord induced blisters when used to make a backpack harness. Conclusions While these results indicate that long-term tagging of juvenile birds is possible with limited impacts on growth, this work does not preclude the need for small-scale studies with individual species. Instead, we hope this provides an informed starting point for further exploration of this topic.

Nonlinear oscillations of a pendulum wrapped around a cylinder

The large oscillations of a pendulum are studied. The pendulum is a material point that is suspended on an elastic cord with nonlinear characteristics. The mass of the cord is accepted. It is wrapped around a perfectly rigid and fixed cylinder. The system has two degrees of freedom. Nonlinearity is due to a geometric and physical nature. A system of two differential nonlinear equations is derived. A numerical solution was performed with the mathematical package MATLAB. The laws of motion, the generalized velocities and accelerations and the phase trajectories are obtained. In order to continue the task by preparing an actual model and conducting experimental research, the projections of the velocity and acceleration of the material point along the horizontal and vertical axes, as well as their magnitudes, are determined. The obtained results are presented graphically and analysed in detail.

Increase the reliability of power supply by using mechanical energy storage devices for low-power consumers

The article analyzes the possibilities of using wind energy in Uzbekistan and studies the possibility of using energy storage devices to build a reliable electricity supply in the regions. In areas with weak winds, a device that first stores wind energy and then generates alternating electricity has been proposed. Energy storage systems have been analyzed, and it is recommended to use mechanical energy storage systems in the energy system consisting of renewable energy sources in the Republic of Uzbekistan. It has been noted that the use of such devices is particularly effective in areas far from centralized power supply, where power supply is not available or where reliability is low. An experimental model of a mechanical energy storage device using an elastic cord braid in a storage system and some equations for its design are given. The possibility and necessity of using this storage system is highly valued in our country. Despite the low power of the original model of the device, it is possible to achieve high results in the future by conducting research in this area and changing the type and composition of the elastic cord. This article presents the results of preliminary research on the development of a new design of mechanical energy storage devices using mechanical elastic cord.

Characterizing Wave Behavior in a Beam Experiment by Using Complex Orthogonal Decomposition

Complex orthogonal decomposition (COD) is applied to an experimental beam to extract the dispersive wave properties from response measurements. The beam is made of steel and is rectangular with a constant cross section. One end of the beam is free and is hung by a soft elastic cord. An impulse is applied to the free-end. The other end is buried in sand to absorb the wave as it travels from the impact site on the free-end; this effectively prevents reflections of the wave off the buried end and emulates a semi-infinite beam. The beam response is measured with an array of accelerometers, whose signals are integrated to obtain an ensemble of displacement signals. Acceleration responses are also compared in the frequency domain to predictions from the Euler–Bernoulli model. COD is applied to the displacement ensemble to obtain complex modal vectors and associated complex modal coordinates (COCs). The spatial whirl rates of nearly harmonic modal vectors are used to extract the modal wave numbers, and the temporal whirl rates of the modal coordinates are used to estimate the modal frequencies. The dispersion relationship between the frequencies and wave numbers compare favorably to those of the theoretical infinite Euler–Bernoulli beam.

Vliv SM-systému cvičení na úroveň posturální stability

The main aim of this study was to find out if exercise with elastic cord improved postural stability in a experimental group. Postural stability was measured by electronic balancing board with variable radius and integrated feedback. The exercise regimen was undertaken twice a week for 3 months. All participants were measured at the beginning of the study and then after 3 months. Participants had to stand on the electronic balance board during 30 seconds with open eyes and kept the board balanced using feedback from the screen. The results were expressed by number from 0 to 100. Twenty-nine elite gymnasts volunteered for this study. Participants did not report any neuromusculoskeletal injuries or other diseases that may affect balance performance. Before participating in the study, all parents of gymnasts read and signed the informed consent form. The participants were assigned to a control group (15 girls; mean age = 13.78±1.62 years; mean height = 1.57±0.09 m; mean mass = 46.16±8.71 kg) and experimental group (14 girls; mean age =14.1±2.0 years; mean height =1.56±0.08 m; mean mass = 45.6±10.55 kg). The total number of time spending in training was 18 hours per week. Experimental group performed 2 hours plus of exercise with elastic cord. One of the aims of the study was to decide if the differences between pre-test and post-test in experimental group will occur. The paired samples t-test was used (p=0.006578; the significance level 95%). The intervention programme with elastic cord improved postural stability in a group of elite gymnasts.