The Refractive Periscope – a Novel Concept

A periscope is an optical device whose function is to allow sighting of objects that are not in direct line of sight with the observer Eye/Screen/Detector. The concept behind the periscope is tilting the optical axis by breaking the rays of light with a mirror or prism so that the image is obtained in the desired location. The periscope has a variety of uses, many of which belong to the military realm. For example, observing from submarines above the sea level surface, looking at the war zone from inside of a tank, directing light into hidden places and more. In this article, the authors will review a new development based on wave guide concept which composes a tube with light reflective walls. This allows us to build a significantly Small-dimensional periscope with respect to a standard periscope that does not use lenses. The authors will also review a number of applications suitable for the reflection periscope.

Studys on the laws of Gauss projection for area distortion

In the regions which has high altitude and is far from central meridian, Gauss projection has bigger area distortion and becomes main factors which influences the accuracy of area measurement. Through researching in detail the area distortion in the three respects that from ground to reference ellipsoid surface from reference ellipsoid surface to Gauss plane and from Gauss plane to compensating level surface, this paper finds the laws of Gauss projection for area distortion, and draws one computation model on 2000 coordinates system. This has contributed to restrict the influence of Gauss projection and choose suitable central meridian and compensating level surface.

A Molecular Dynamics Study of Heat Transfer Enhancement during Phase Change from a Nanoengineered Solid Surface

This study investigates the enhancement of the rate of evaporation from a nanoengineered solid surface using non-equilibrium molecular dynamics simulation. Four different types of surface modifications were introduced to examine the thermal transportation behavior. The surface modification includes: (1) transformation of surface wetting condition from hydrophobic to hydrophilic, (2) implementing nanostructures on the smooth surface, (3) cutting nano slots on the smooth surface and (4) introducing nano-level surface roughness. Evaporation behavior from the same effective surface area was also studied. The simulation domain consisted of three distinct zones: solid base wall made of copper, a few layers of liquid argon, and a vapor zone made of argon. All the nano-level surface modifications were introduced on the solid base surface. The few layers of liquid argon representing the liquid zone of the domain take heat from the solid surface and get evaporated. Outside this solid and liquid zone, there is argon vapor. The simulation began at the initial time t = 0 ns and then was allowed to reach equilibrium. Immediately after equilibrium was achieved on all three-phase systems, the temperature of the solid wall was raised to a higher value. In this way, thermal transportation from the solid wall to liquid argon was established. As the temperature of the solid wall was high enough, the liquid argon tended to evaporate. From the simulation results, it is observed that during the transformation from hydrophobic to hydrophilic conditions, enhancement of evaporation takes place due to the improvement of thermal transportation behavior. At the nanostructure surface, the active nucleation sites and effective surface area increase which results in evaporation enhancement. With nano slots and nano-level surface roughness, the rate of evaporation increases due to the increase of solid-liquid contact area and effective surface area.

Association Between Hip Rotation and Activation of the Quadriceps and Gluteus Maximus in Male Runners

Background: Although running can provide health benefits, knee joint injuries are frequently reported by recreational runners. To date, the precise mechanism responsible for anterior knee pain remains elusive, and the source of symptoms is debated. Inconsistencies are found in the literature pertaining to the relationship between hip mechanics and activity in the quadriceps and gluteus maximus (GMax) during the running gait. Purpose/Hypothesis: To investigate the correlations between hip rotation and the activity in the quadriceps and GMax during running. We hypothesized that increased hip rotation is correlated with decreased activity in these muscles. Study Design: Descriptive laboratory study. Methods: A cohort of 30 healthy recreational runners volunteered to participate in the study (mean ± SD age, 28.8 ± 5.66 years; height, 1.73 ± 0.05 m; mass, 69 ± 6.3 kg; body mass index, 23.02 ± 1.42 kg/m2). Surface electromyography (EMG) data were obtained from the GMax, vastus medialis obliquus (VMO), and vastus lateralis obliquus (VLO). These data were synchronized with a motion capture system during a level-surface running activity at a speed of 3.2 m/s. Results: A significantly strong, negative correlation was found between the hip internal rotation angle and EMG activity of the GMax and the VMO. However, the VLO showed a significant, moderate, and positive correlation of activity with the hip internal rotation angle. Conclusion: The present study showed that during level-surface running, decreased GMax activity may be the cause of distal joint injuries and alteration in quadriceps muscle activity. Clinical Relevance: Because GMax activity is important for controlling the lower body mechanics during running, evaluating GMax activity and internal hip rotation angle is important to prevent the running-related knee injuries that are linked to quadriceps deficits, such as patellofemoral pain. Additionally, clinicians and trainers should consider strengthening the GMax while rehabilitating running-related knee injuries.