Mirror Walls Research Articles

Исследование концентраторных фотоэлектрических модулей с отражающими элементами вторичной оптики

The characteristics of concentrator photovoltaic modules based on a 120 × 120 mm Fresnel lens with secondary concentrators in the form of hollow aluminum focons with internal mirror walls are studied. The optimal sizes and configurations of secondary concentrators are determined to increase the efficiency of focusing systems of concentrator modules. The maximum value of the allowable misorientation angle was obtained, equal to ±0.75°, corresponding to a power drop to a level of 90% relative to the maximum power value of the concentrator photovoltaic module at normal beam incidence. For a module with the most efficient focon 40 mm high and side face slope angles of 17°, the maximum efficiency of the module under laboratory conditions was obtained, equal to 35.15%. Under natural conditions, the efficiency value reached 33.8 The results obtained correspond to the level achieved for the best foreign analogues.

Estimation of Insolation of the Mirror Hall of a Unique Building

For studying of insolation of architectural objects with mirror walls, reflected solar radiation shall be accounted for. Most ways of insolation duration estimation are based on geometry of visible solar path, namely the geometrical model of the process of insolation of a point of Earth surface. This model is the daily cone of sunrays. At the same time, there is a daily cone of reflected sunrays in a point of a reflective surface. Using this model, insolation of a mirror reception hall in a unique building in the Russian South was studied. Geometric modelling has shown that on the floor of the hall of mirrors in some areas there is an addition of three reflected from the faces and the corresponding direct beams of solar radiation. The shots made by means of the thermal camera testo 882 have confirmed reliability of the proposed geometrical model.

Performance enhancements of conventional solar still using reflective aluminium foil sheet and reflective glass mirrors: energy and exergy analysis.

Many researchers are seeking simple and successful solutions to increase the output from the solar distiller. In this research work, reflective mirrors and reflective aluminium foil sheet were fixed on inner surfaces of the single-slope solar distiller, leading to more water production. The presence of reflective mirrors and reflective aluminium foil sheet on inner surfaces of the solar distillate permits the reflection of solar radiation falling inside the basin. Experiments were carried out on three stills: the first distiller is conventional solar still with black painted walls (CSS-BPW); the second distiller is conventional solar still with reflective aluminium foil sheet walls (CSS-RAFW); and the third distiller is conventional solar still with reflective glass mirror walls (CSS-RGMW). The maximum total drinking water productions from the CSS, CSS-RAFW and the CSS-RGMW are 3.41, 5.1 and 5.54 kg/m2, respectively. Compared to the CSS-BPW, the production of drinking water was increased by 68.57% when using the reflective glass mirrors and 48.57% when using the reflective aluminium foil sheet.

Mirrors inhibit growth and stimulate lateralized response to prey in larvae of the Mexican axolotl Ambystoma mexicanum

Laterality of brain and behavior at the individual and/or group level is a characteristic of all vertebrate classes, including amphibians. It is well recognized that the right-eye/left-hemisphere system is more efficient in discrimination of edible and non-edible items. However, the ontogenesis of this or other lateralized responses has rarely been investigated. Here we present the first evidence of ontogenesis of right-eye/left-hemisphere response to live food in the Mexican axolotl, Ambystoma mexicanum. Furthermore, we test a possible influence of mirror images imitating the presence of conspecifics on laterality of the reaction to food, as well as on the growth and development of axolotls; we then compare the results to those known for anuran tadpoles. We placed the newly hatched axolotls into aquaria either with transparent or mirror walls individually (first experiment), or in a group of 25 animals (second experiment). The larvae were fed Artemia salina nauplii and regularly scored for the number and direction (either left or right) of their attacks towards the prey. Body length was measured twice a month. The statistically significant lateralized response to food was first detected in only three-week-old larvae and was right-sided, suggesting processing of visual information in the left brain hemisphere. At the same age, the left hemisphere seems to start its specialization in more efficient perception of prey. In both experiments we found a significant difference between the larvae growing in the transparent and mirror aquaria, with a tendency towards a stronger right-sided lateralization in the mirror aquaria. Also, the mirror walls inhibited larval growth, especially at the age of 60–75 days. A similar phenomenon is known in overcrowding of anuran tadpoles, which is discussed in terms of visual brain stimulation.

Pattern of Lateralized Behaviors in a Caudate Amphibian, <i>Ambystoma mexicanum</i>

Laterality of brain and behavior at the individual and/or group level is a characteristic of all vertebrate classes. The general pattern of left-right asymmetry in vertebrates is so that left-eye/right-hemisphere system is used to detect socially important images, like conspecifics, and also recognize danger, while the right-eye/left-hemisphere system is used to discriminate prey and food items from inedible objects. However, the pattern of motor and visual lateralization in caudate amphibians is poorly investigated to date. Here we present the first evidence of individual and group level motor and visual lateralization in sexually mature and immature larvae of the Mexican axolotl, Ambystoma mexicanum , thus presenting a comprehensive characteristic of the lateralized behavioral pattern in a salamander species. First, we performed four successive tests to assess asymmetry in rapid C-start and measure its characteristics in responses to startle stimuli in sexually immature larvae. We experimentally showed that axolotls exhibited a leftward population bias in each of four C-start tests, of which the bias was significant in the second test and in the pooled data for all four tests. Second, in mature axolotls we have found right-sided individual level asymmetry and, at the group level, a tendency to react more actively to food items (live chironomid larvae) appeared in their right visual hemifield. Third, individual axolotl larvae been placed in the square aquarium with two opposite mat walls and two opposite mirror walls preferred to stay near to mirror walls, rather than near to mat walls. At the group level, this preference increased over three successive tests and reached significance in the third test and in the pooled data. At both individual and group levels axolotls showed statistically significant lateralization, preferring to inspect the mirror walls with their left eyes in all three tests. Overall, the expressed pattern of lateralization in the Mexican axolotl corresponds to the general pattern of lateralization established for other vertebrates including anuran amphibians.

Proposal for achieving in-plane magnetic mirrors by silicon photonic crystals

Magnetic mirrors exhibit predominant physical characteristics such as high surface impedance and strong near-field enhancement. However, there is no way to implement these materials on a silicon lab chip. Here, we propose a scheme for an in-plane magnetic mirror in a silicon-based photonic crystal with a high-impedance surface, in contrast to the previous electric mirrors with low surface impedance. A tortuous bending waveguide with zero-index core and magnetic mirror walls is designed that exhibits high transmission and zero phase change at the waveguide exit. This type of magnetic mirror opens the door to exploring the physics of high-impedance surfaces and applications in integrated photonics.

The Lists of W. G. Sebald

The Lists of W. G. Sebald

Effect of boundary conditions on the energy spectra of semiconductor quantum dots calculated in the effective mass approximation

We consider semiconductor quantum dots shaped as a rectangular prism and a sphere, in the framework of the effective mass approximation. The Schrödinger equation was solved assuming a specular reflection of a particle from the boundary of the quantum dot, which will set the equivalent values for the particle wave function for an arbitrary original point inside the quantum dot and its image in the quantum dot wall. It is shown that the results obtained in this approximation for some classical problems coincide with those based on traditional approaches using “impenetrable walls” or periodic Born-von Karman boundary conditions. Additionally, several problems that are difficult to treat using the traditional approaches could be easily resolved with the suggested mirror-type boundary conditions. It is also shown that this “mirror walls” approach is favorable for effective mass approximation. The comparison of the calculated energy spectra with existing experimental data shows reasonable agreement between the theory and the experiment.

COMPARATIVE ANALYSIS OF THE EFFICIENCY OF THERMAL SYSTEMS BUILT WITH REFLECTIVE INSULATORS WITH AND WITHOUT VACUUM

The use of reflective surfaces functioning as thermal insulators has grown significantly over the years. Reflective thermal insulators are materials that have several characteristics such as low emissivity, low absorptivity and high reflectivity in the infrared spectrum. The use of these materials has grown very much lately, since they contain several important radioactive properties that minimize the heat loss of thermal systems and cooling systems that are used to block the heat on the roof of buildings. A system made of three surfaces of 430 stainless steel mirror was built to analyze the influence of reflective surfaces as a way to reduce the heat loss and thereby conserve the energy of a thermal system. The system was analyzed both with and without the presence of vacuum, and then compared with a system that contained glass wool between the stainless steel mirror walls, since this insulator is considered resistive and also broadly used around the world in thermal systems. The reflectivity and emissivity of the surfaces used were also measured in this experiment. A type K thermocouple was fixed on the wall of the system to obtain the temperature of the stainless steel mirror surfaces and to analyze the thermal behavior of each configuration used. The results showed an efficiency of 13% when the reflective surfaces were used to minimize the heat loss of the thermal system. However, the system with vacuum had the best outcome, a 60% efficiency. Both of these were compared to the system made of glass wool as a thermal insulator.

Kinetics of collisionless gas: Equalization of temperature, growth of the coarse-grained entropy and the Gibbs paradox

The Poincare model for dynamics of a collisionless gas in a rectangular parallelepiped with mirror walls is considered. The question on smoothing of the density and the temperature of this gas and conditions for the monotone growth of the coarse-grained entropy are discussed. All these effects provide a new insight of the classical paradox of mixing of gases.

Кинетика бесстолкновительного газа: выравнивание температуры, возрастание грубой энтропии и парадокс Гиббса

The Poincare model for dynamics of a collisionless gas in a rectangular parallelepiped with mirror walls is considered. The question on smoothing of the density and the temperature of this gas and conditions for the monotone growth of the coarse-grained entropy are discussed. All these effects provide a new insight of the classical paradox of mixing of gases.

Rabbit preference for cages and pens with or without mirrors

Five-week-old Pannon White rabbits were housed in a closed climatized rabbitry and randomly assigned to either pens (56 rabbits) having a basic area of 1 m 2 with a stocking density of 16 and 12 rabbits/m 2 or to 18 individual cages (0.24 m 2/cage). The pens and the cages were divided into two halves and animals could move freely between the two halves through swing doors. The walls of one half of the pens and cages were completely covered with mirrors while the other half was covered with white plastic panels. A 24 h video recording was made twice a week using infrared cameras and the number of rabbits in each pen and cage was counted every 15 min. The duration of the trial was 6 weeks. The lighting period was 16L/8D. In each half of the cage or pen, a feeder and nipple drinkers were available and feed intake was measured separately. Throughout the entire rearing period, 72% of the individually caged rabbits showed a preference for the cage half enriched with mirrors ( P < 0.001). This preference decreased slightly with increasing age. Preference toward the cage half provided with mirror walls was independent of the time of day; in other words, during the active period (23:00–05:00) corresponding to the dark part of the day, rabbits continued to prefer the mirrored half even if the vision of the reflected image was reduced. The presence of conspecifics at different stocking densities (12 vs. 16 rabbits/m 2) did not reduce this interest in mirrors: averaging the ages, 66% of animals living at 16 rabbits/m 2 stocking density and 63% of those living at 12 rabbits/m 2 density were found in the half pen with mirrors ( P < 0.001). Group-penned rabbits showed a marked preference toward mirrors during the active period (73–76% for 12 and 16 rabbits/m 2 stocking densities, respectively; P < 0.001). The results suggest that the presence of mirrors offers advantages perhaps related to comfort and welfare, and therefore might be used as environmental enrichment for fattening rabbits and advised for rabbits caged individually for long periods.

The limits of the mirror box concept as an overcast sky simulator

A new overcast sky simulator was developed in the fall of 2000 at the Faculty of Architecture at NTNU, Trondheim, Norway. During the design process the limits of the mirror box concept as an overcast sky simulator were investigated. One of the limits is uneven distribution of luminance over the surface of the luminous ceiling. The reason for this is the uneven light distribution on the diffusing canvas from the light sources. The diffusing canvas itself may not be a perfect lambertian diffuser either. Another limit is the uneven luminance distribution on the mirror walls due to the stepwise changes of luminance on the mirror walls. The methods for reducing those limits are discussed and described.

Plant growth during the greenhouse II experiment on the Mir orbital station

We carried out three experiments with Super Dwarf wheat in the Bulgarian/Russian growth chamber Svet (0.1 m 2 growing area) on the Space Station Mir. This paper mostly describes the first of these NASA-supported trials, began on Aug. 13, 1995. Plants were sampled five times and harvested on Nov. 9 after 90 days. Equipment failures led to low irradiance (3, then 4 of 6 lamp sets failed), instances of high temperatures (ca. 37 °C), and sometimes excessive substrate moisture. Although plants grew for the 90 d, no wheat heads were produced. Considering the low light levels, plants were surprisingly green, but of course biomass production was low. Plants were highly disoriented (low light, mirror walls?). Fixed and dried samples and the root module were returned on the U.S. Shuttle Atlantis on Nov. 20, 1995. Samples of the substrate, a nutrient-charged zeolite called Balkanine, were taken from the root module, carefully examined for roots, weighed, dried, and reweighed. The Svet control unit and the light bank were shipped to Moscow. An experiment validation test (EVT) of plant growth and experimental procedures, carried out in Moscow, was highly successful. Equipment built in Utah to measure CO 2, H 2O vapor, irradiance, air and leaf (IR) temperature, O 2, pressure, and substrate moisture worked well in the EVT and in space. After this manuscript was first prepared, plants were grown in Mir with a new light bank and controller for 123 d in late 1996 and 39 days in 1996/1997. Plants grew exceptionally well with higher biomass production than in any previous space experiment, but the ca. 280 wheat heads that were produced in 1996 contained no seeds. Ethylene in the cabin atmosphere was responsible.

Whispering Gallery Orbits in the Bunimovich Stadium

Abstract A new visualization method is found for investigating the complex ray dynamics of whispering gallery orbits inside the Bunimovich stadium. Regarding the whispering gallery as mirror cabinet, a fractal system of virtual images of the mirror walls is found which reflects the sensitive dependence of the dynamic behavior on the initial conditions.

Chaotic billiards seen as mirror cabinets

A new visualization method is found for investigating the complex ray dynamics inside chaotic billiards. Regarding the billiards as mirror cabinets the resulting system of virtual images of the mirror walls reveals a fractal structure which corresponds to the chaotic trajectories of light rays or billiard balls inside.

Nonintegrable Stadium Billiard seen as Mirror Cabinet

Abstract The Bunimovich stadium billiard is treated as a mirror cabinet seen from inside. The resulting system of virtual images of the mirror walls reveals a fractional structure which corresponds to the chaotic trajectories of light rays or billiard balls inside the stadium.

Optical transmission and reflection by a slot with mirror walls in a semiconductor waveguide

The method of expansion of radiation carried by a waveguide mode into plane waves is used to analyze the characteristics of reflection and transmission by a slot with mirror walls in a semiconductor waveguide allowing for the change in the beam profile at interfaces between media. In the case of the AlxGa1–xAs–AlyGa1–yAs–AlxGa1–xAs system such a slot operates as an effective mirror when its width is about 1 μ and depth greater by 0.1 μ than half the waveguide thickness.