Clear Sunny Day Research Articles

Photodynamic therapy for actinic keratosis: Is the European consensus protocol for daylight PDT superior to conventional protocol for Aktilite CL 128 PDT?

BackgroundTopical photodynamic therapy (PDT) is an established treatment modality for various dermato-oncologic conditions. In Europe, initially requiring irradiation with red light, PDT of actinic keratosis (AK) can now also be carried out with exposure to daylight that has been clinically proven to be as effective as and less painful than red light. ObjectivesIn this paper, we propose a comparison between the conventional protocol for Aktilite CL 128 (red light source) PDT and the European consensus protocol for daylight PDT — with the exposure is assumed to be performed during either a clear sunny day or an overcast day — in the treatment of AK with methyl aminolevulinate through a mathematical modeling. MethodThis already published modeling that is based on an iterative procedure alternating determination of the local fluence rate and updating of the local optical properties enables to estimate the local damage induced by the therapy. ResultsThe European consensus protocol for daylight PDT during a sunny day and an overcast day provides, on average, 6.50 and 1.79 times higher PDT local damages at the end of the treatment than those obtained using the conventional protocol for Aktilite CL 128 PDT, respectively. ConclusionsResults analysis shows that, even performed during an overcast day, the European consensus protocol for daylight PDT leads to higher PDT local damages than the efficient conventional protocol for Aktilite CL 128.

An experimental study of floating wick basin type vertical multiple effect diffusion solar still with waste heat recovery

In the present study, a floating wick basin type vertical multiple effect diffusion solar still with waste heat recovery (FW-BVMED-HR) has been constructed by modifying the conventional design of basin type VMED solar still (reference still). The reference still has been modified by incorporating improvements like multiple floating wicks in the basin and heat exchanger for waste heat recovery in order to determine the cumulative effect of both of these improvements. The performance of the FW-BVMED-HR still was compared with reference still under identical weather and operational conditions by running them side by side simultaneously. Both the stills were made of same dimensions and materials, and consisted of four effects. On a clear sunny day, the distillate productivity of FW-BVMED-HR still was found to be 21% higher than the reference still. High distillate productivity resulted, due to high convective heat transfer by humid basin air from high temperature float wick surface to first partition plate, feed water pre-heating from waste heat recovery, reduced basin bottom and side losses, and high night distillate productivity as a result of additional heat stored in multiple floating wicks.

The influence of the spatial heterogeneity of vegetation cover and surface topography on vertical CO2 fluxes within the atmospheric surface layer

The influence of the spatial heterogeneity of vegetation cover and topography on CO2 fluxes in the atmospheric surface layer is estimated using a two-dimensional (2D) hydrodynamic model of turbulent exchange. A ~4.5-km-long profile that crossed a hilly area with a mosaic vegetation cover in Tula region was selected for model experiments. During the first experiment, a wind field and vertical fluxes were calculated by the 2D model for the entire selected profile with respect to the horizontal heterogeneity of the vegetation cover and surface topography. In the second experiment, the profile was considered an assemblage of elementary independent homogeneous segments; for each of them, vertical fluxes were calculated by the 2D model with the assumption of ‘zero’ horizontal advection, i.e., the required functions are independent of the horizontal coordinates. The influences of any boundary effects that appear at the interface between the different vegetation communities and at topographical irregularities on the turbulent regime are ignored in this case. For the profile selected, ignoring the horizontal advection, disturbances in the wind field that appeared at surface topography irregularities, and boundaries between different vegetation communities can lead to a 26% underestimation of the total CО2 absorption by the ground surface on a clear sunny day under summer weather conditions.

Spatial heterogeneity in stand characteristics alters water use patterns of mountain forests

Mountain landscapes have complex and rugged topographies, with abrupt spatial and temporal changes in microclimate and soil properties, factors that directly affect tree growth and canopy processes. These may alter functional relationships over short spatial scales, rendering the use of allometry in scaling tree water use (TWU) from single trees to stand level less accurate. On the other hand, canopy processes, especially stomatal conductance are sensitive to the environmental conditions prevailing above the canopy. Given that these also change rapidly in a mountain landscape, we speculate that patterns of water use in a complex landscape are determined by the interaction between stand structure and canopy conductance. We examined forest stand structure, microclimate and sap flux density (Js) in two forest stands distributed at 50m and 330m elevations of the Dinghushan Mountain in south China to determine how they influence tree functional allometry for scaling up stand water use. Tree sapwood area (SA) was correlated with the diameter at breast height (DBH) irrespective of species and location within the forest catchment. The maximum sap flux density (Js) on a clear sunny day ranged from 18±9 to 48±12 and 25±8 to 64±11gm−2s−1 in the 330m and 50m forest stands, respectively. Differences among trees and between forest stands were significant (p<0.05). Daily maximum tree water use (TWU) ranged from 2±4 to 36±12kgd−1 and 4±3 to 42±11kgd−1 in the 330 and 50m, respectively. Differences between the stands were significant. Within a stand, TWU was correlated with DBH irrespective of species. This functional relationship was, however, different between the forest stands, resulting in different E estimates for the respective stands. Cross-site variations were due to differences in vapor pressure deficit (VPD), photosynthetic photon flux density (PPFD) and leaf specific canopy conductance (gt). While trees responded in a similar manner to the microclimatic environment, between-site differences in stand characteristics shifted the functional relationships. Thus, in this complex mountain terrain, using a universal, site-specific allometric equation in scaling up sap flow from single trees to catchment-scale can lead up to 30% inaccuracy.

Optimization of Solar Photocatalytic Degradation of Chloroxylenol Using TiO2, Er3+/TiO2, and Ni2+/TiO2 via the Taguchi Orthogonal Array Technique

In this study, the optical properties of a TiO2 photocatalyst were enhanced with various impregnations of Er3+ and Ni2+ separately, using the impregnation method as photocatalysts for the direct solar photolysis degradation of chloroxylenol. The synthesized Er3+/TiO2 and Ni2+/TiO2 catalysts were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX), metal mapping, and ultraviolet visible (UV–Vis) spectroscopy. The results showed that the Er3+/TiO2 and Ni2+/TiO2 nano-particles have the same structures of TiO2 nano-particles with little difference in particle size. The Er3+ and Ni2+ ions were well-distributed on the TiO2 surface, and it was found that the maximum band gap decreased from 3.13 eV for intrinsic TiO2 to 2.63 eV at 1.8 wt % Er3+/TiO2 and to 2.47 eV at 0.6 wt % for Ni2+/TiO2. The initial concentration of chloroxylenol, catalyst loading, and pH of the solution are the most important factors affecting the solar photocatalytic degradation efficiency that were optimized using Design Expert software (version 6.0.10, Minneapolis, MN, USA, 2003). The results showed that the optimal conditions for chloroxylenol degradation include a pH of 4, TiO2 loading at 3 g/L, and a chloroxylenol concentration of 50 mg/L. These conditions resulted in a degradation efficiency of 90.40% after 60 min of direct solar irradiation, wherein the solar energy recorded during a clear sunny day is 1000 W/m2. However, some experiments were conducted on a semi-cloudy day to cover all weather stated and to study the degradation kinetics. During semi-cloudy day experiments, using Er3+/TiO2 and Ni2+/TiO2 with a solar irradiation activity of 600 W/m2 for a 60 min exposure at optimal conditions increased the degradation efficiency from 68.28% for intrinsic TiO2 to 82.38% for Er3+/TiO2 and 80.70% for Ni2+/TiO2.

Impact of Photovoltaics on Frequency Stability of Power System During Solar Eclipse

This paper analyses the influence of variable production of photovoltaic plants on the synchronous continental Europe interconnection during the solar eclipse of March 20, 2015. For countries with a high share of photovoltaics, the daily photovoltaics generation is estimated for the worst-case scenario – a clear sunny day. The presented results of long-term dynamic simulations focus on frequency stability (taking into account daily load diagram, secondary and primary frequency control, system inertia, settings of frequency protections and load frequency shedding).

Measured thermal & daylight performance of an evacuated glazing using an outdoor test cell

Outdoor characterization of thermal and daylight performance of an evacuated (vacuum) glazing has been conducted using an outdoor test cell for clear sunny day, intermittent day and overcast days. An average overall heat transfer coefficient of 1.4W/m2K was found for vacuum glazing. Solar heat gain coefficient of vacuum glazing varied between 0.58 and 0.19. Vacuum glazing has potential to reduce 53% heat loss compared to a same area of double-glazing while offering nearly equal amount of heat gain. Internal daylight illuminance was found to be similar to double glazing indicating that the presence of small pillars inside vacuum glazing had no significant visual impact.

The Effects of Driving Environment on the Mental Workload of Train Drivers

A study is carried out to investigate the effects of driving environment on the mental workload of train drivers while driving. The driving task is performed under three environmental conditions, i.e. clear sunny day, rainy day and rainy night driving. Electroencephalography (EEG) measurements are recorded from the Fz and Pz channels of fifteen male subjects aged between 24 to 48 years old. The mean alpha power is monitored as a function of time as this signal reflects the variations in mental workload of the drivers. The results exhibit that the signal pattern for rainy night driving condition is significantly different compared to others. This finding indicates that the train drivers show an increase in mental workload after six minutes of driving under rainy night condition. The results demonstrate a percentage difference in mean alpha power of 37% between daytime and rainy night driving conditions during the early periods of driving. This indicates that the mental workload of train drivers tends to be low with an increased level of sleepiness under such conditions, which are signs of low vigilance.

Calibrating an optimal condition model for solar water disinfection in peri-urban household water treatment in Kampala, Uganda

In low income settlements where the quality of drinking water is highly contaminated due to poor hygienic practices at community and household levels, there is need for appropriate, simple, affordable and environmentally sustainable household water treatment technology. Solar water disinfection (SODIS) that utilizes both the thermal and ultra-violet effect of solar radiation to disinfect water can be used to treat small quantities of water at household level to improve its bacteriological quality for drinking purposes. This study investigated the efficacy of the SODIS treatment method in Uganda and determined the optimal condition for effective disinfection. Results of raw water samples from the study area showed deterioration in bacteriological quality of water moved from source to the household; from 3 to 36 cfu/100 mL for tap water and 75 to 126 cfu/100 mL for spring water, using thermotolerant coliforms (TTCs) as indicator microorganisms. SODIS experiments showed over 99.9% inactivation of TTCs in 6 h of exposure, with a threshold temperature of 39.5 ± 0.7°C at about 12:00 noon, in the sun during a clear sunny day. A mathematical optimal condition model for effective disinfection has been calibrated to predict the decline of the number of viable microorganisms over time.

광튜브와 디쉬형 집광기의 자연채광 성능 예측 및 비교 연구

본 연구에서는 북측창을 가진 강의실 내의 불균형적인 실내 조도차이를 개선하기 위해 두 가지의 자연채광시스템을 적용하였을 경우에 대하여 Photopia를 이용한 성능 시뮬레이션을 수행하였다. 특히, 본 연구에서는 태양고도가 최고 <TEX>$80^{\circ}$</TEX> 이르는 하지에 청천공 상태 하에서의 태양고도에 따른 각 시스템의 배광분포곡선을 구하고 이를 이용하여 실내 조도 등을 분석하였다. 작업면의 경우, 창측과 복도측의 평균 조도차가 1000lx를 초과하였는데 시스템 설치 후에는 그 차이가 상당히 줄어드는 것으로 나타났다. 광튜브 시스템 설치시 906lx에서 603lx로 감소하였으며, 디쉬형 시스템은 308lx까지 줄어들었다. 광튜브의 성능은 태양고도에 영향을 크게 받았으며 디쉬형 집광기는 지속적인 태양추적으로 인하여 태양고도에 관계없이 일정한 성능을 보여주었다. This study presents the simulation results of Photopia when a lecture room with north-facing windows were illuminated by two different types of daylighting systems to improve the imbalance in its lighting conditions. Especially, the candela power distribution curves (CDCs) on a clear sunny day at the summer solstice, reaching <TEX>$80^{\circ}$</TEX> in solar altitude, were analyzed with respect to the illuminance available at task areas (work planes). The difference between its illuminance on the north and south areas exceeded 1,000 lux without any daylighting system. This, however, decreased drastically with the application of a daylighting system. When a light tube system was introduced, it reduced from 906lx to 603lx and, even further to 308lx with the application of a dish concentrator system. Generally, the performance of a light tube system was greatly influenced by solar altitude while its effect on the dish concentrator system was rather negligible.

The collapse of turbulence in the atmospheric boundary layer

A well-known phenomenon in the atmospheric boundary layer is the fact that winds may become very weak in the evening after a clear sunny day. In these quiet conditions usually hardly any turbulence is present. Consequently this type of boundary layer is referred to as the quasi-laminar boundary layer. In spite of its relevance, the appearance of laminar boundary layers is poorly understood and forms a long standing problem in meteorological research. Here we investigate an analogue problem in the form of a stably stratified channel flow. The flow is studied with a simplified atmospheric model as well as with Direct Numerical Simulations. Both models show remarkably similar behaviour with respect to the mean variables such as temperature and wind speed. The similarity between both models opens new way for understanding and predicting the laminarization process. Mathematical analysis on the simplified model shows that relaminarization can be understood from the existence of a definite limit in the maximum sustainable heat flux under stably stratified conditions. This fascinating aspect will be elaborated in future work.

Ultraviolet radiation tolerance of the Antarctic springtail,Gomphiocephalus hodgsoni

AbstractThis is the first study to examine the tolerance of Antarctic springtails (Collembola) to ultraviolet radiation (UV). Survival of extended attenuated exposure to sunlight was examined for both individuals and aggregations of the speciesGomphiocephalus hodgsoniCarpenter over a 10 day period. Both individuals and aggregations demonstrated significantly higher survival and moult rates from control treatments kept in the dark to those exposed to UV. A photo-inhibitive element to moulting is indicated that may function to protect post-ecdysial springtails when their emergent cuticles are more sensitive to the external environment. DNA damage was measured in springtails directly exposed to sunlight for 5 h on a clear sunny day. Significant differences were found between treated animals and controls kept in the dark. There was some reduction of damage 12 and 24 h after exposure, when springtails had been placed in the dark to recover. This indicates the up-regulation of DNA repair mechanisms, with the 12 h treatment in particular showing no significant difference with controls. In addition to providing a first look at UV tolerance in these soil arthropods, these findings recommend employing strict protocols for collections of sample material for subsequent biological analysis in order to minimize the interactive effects of photo-damage.

Modeling, design and thermal performance of a BIPV/T system thermally coupled with a ventilated concrete slab in a low energy solar house: Part 2, ventilated concrete slab

This paper is the second of two papers that describe the modeling and design of a building-integrated photovoltaic–thermal (BIPV/T) system thermally coupled with a ventilated concrete slab (VCS) adopted in a prefabricated, two-storey detached, low energy solar house and their performance assessment based on monitored data. The VCS concept is based on an integrated thermal–structural design with active storage of solar thermal energy while serving as a structural component – the basement floor slab (∼33 m 2). This paper describes the numerical modeling, design, and thermal performance assessment of the VCS. The thermal performance of the VCS during the commissioning of the unoccupied house is presented. Analysis of the monitored data shows that the VCS can store 9–12 kWh of heat from the total thermal energy collected by the BIPV/T system, on a typical clear sunny day with an outdoor temperature of about 0 °C. It can also accumulate thermal energy during a series of clear sunny days without overheating the slab surface or the living space. This research shows that coupling the VCS with the BIPV/T system is a viable method to enhance the utilization of collected solar thermal energy. A method is presented for creating a simplified three-dimensional, control volume finite difference, explicit thermal model of the VCS. The model is created and validated using monitored data. The modeling method is suitable for detailed parametric study of the thermal behavior of the VCS without excessive computational effort.

Performance of a silicon photovoltaic module under enhanced illumination and selective filtration of incoming radiation with simultaneous cooling

A promising option to reduce the cost of silicon photovoltaic systems is to concentrate the sunlight incident on the solar cells to increase the output power. However, this leads to higher module temperatures which affects performance adversely and may also cause long term damage. Proper cooling is therefore necessary to operate the system under concentrated radiation. The present work was undertaken to circumvent the problem in practical manner. A suitable liquid, connected to a heat exchanger, was placed in the housing of the photovoltaic module and unwanted wavelengths of solar radiation were filtered out to minimise overheating of the cells. The selection of the liquid was based on factors such as boiling point, transparency towards visible radiation, absorption of infrared and ultraviolet radiation, stability, flow characteristics, heat transfer properties, and electrical nonconductivity. Using a square parabolic type reflector, more than two fold increase in output power was realised on a clear sunny day employing a 0.13 m 2 silicon solar module. Without the cooling arrangement the panel temperature rose uncontrollably.

Influence of the boundary layer development on the ozone concentration over an urban area

Results obtained during two campaigns (summer 2004 and autumn 2005) of observation of the planetary boundary layer dynamics over the Sofia city urban area are presented. An EARLINET scanning aerosol lidar, an ozone analyser and a ground meteorological station were used during the observations. The stable boundary layer height varied from 200 m to 600 m during the different seasons. The residual layer was found to be at 700–1200 m, being destroyed between 10:30 and 12:30 LST. The mixing layer developed up to heights of about 800–1300 m. The ground level ozone concentration was measured to be from 10 µg/m3 to 90 µg/m3. The convective boundary layer formation in three case studies (a clear sunny day, a partial solar eclipse, and in the presence of internal atmospheric gravity waves) are presented. In particular, the mixing layer development and the residual layer destruction are studied and considered, along with the relevant ground level ozone concentration variation.

THE AQUATIC-POLYCARBONATE SKYLIGHT FOR SURABAYA INDONESIA

This paper will indicate of how appropriate use of aquatic skylight module installed on buildings in the tropical zone compared to the ones in the subtropical climate. In order for energy saving strategies, the aquatic-polycarbonate skylight system is used in the tropical climate. In the tropical hot humid climate, Indonesia has received huge amount of global direct and diffuse radiations on horizontal roofs throughout the year, approximately 525 watts per square meter of solar radiation will impact on flat roofs or skylights on a clear sunny day in Surabaya city. Ironically, most of the commercial and institution buildings are equipped with Western skylight styles in Surabaya without any modifications. The aquatic-polycarbonate skylight is the system that will control daylight, scatter direct solar heat radiation, cool the indoor polycarbonate surface temperature, and collect solar hot water at the same time. The concept of using the water as shading device has three goals: first of all, the flushing water in the polycarbonate holes tries to scatter horizontal or tiled skylight direct sun-ray radiation, and minimize the direct sun heat temperature on the polycarbonate with flushing water continuously. Secondly, the sparkle flushing water in series of square holes of polycarbonate will bounce and disperse the direct sunlight into the space below enhancing daylight patterns. Finally, while bouncing, sparkling and scattering direct sunlight, those series of flushing water holes would also collect the solar heat radiation as solar hot water. Each system could works nicely to absorb, to scatter, to minimize, and to obtain the solar heat radiation for solar hot water in buildings. This strategy aims to provide a clean environment living zones with applying passive heating and cooling systems.

THE AQUATIC-POLYCARBONATE SKYLIGHT FOR SURABAYA INDONESIA

This paper will indicate of how appropriate use of aquatic skylight module installed on buildings in the tropical zone compared to the ones in the subtropical climate. In order for energy saving strategies, the aquatic-polycarbonate skylight system is used in the tropical climate. In the tropical hot humid climate, Indonesia has received huge amount of global direct and diffuse radiations on horizontal roofs throughout the year, approximately 525 watts per square meter of solar radiation will impact on flat roofs or skylights on a clear sunny day in Surabaya city. Ironically, most of the commercial and institution buildings are equipped with Western skylight styles in Surabaya without any modifications. The aquatic-polycarbonate skylight is the system that will control daylight, scatter direct solar heat radiation, cool the indoor polycarbonate surface temperature, and collect solar hot water at the same time. The concept of using the water as shading device has three goals: first of all, the flushing water in the polycarbonate holes tries to scatter horizontal or tiled skylight direct sun-ray radiation, and minimize the direct sun heat temperature on the polycarbonate with flushing water continuously. Secondly, the sparkle flushing water in series of square holes of polycarbonate will bounce and disperse the direct sunlight into the space below enhancing daylight patterns. Finally, while bouncing, sparkling and scattering direct sunlight, those series of flushing water holes would also collect the solar heat radiation as solar hot water. Each system could works nicely to absorb, to scatter, to minimize, and to obtain the solar heat radiation for solar hot water in buildings. This strategy aims to provide a clean environment living zones with applying passive heating and cooling systems.

Maximum power point traking controller for PV systems using neural networks

This paper presents a development and implementation of a PC-based maximum power point tracker (MPPT) for PV system using neural networks (NN). The system consists of a PV module via a MPPT supplying a dc motor that drives an air fan. The control algorithm is developed to use the artificial NN for detecting the optimal operating point under different operating conditions, then the control action gives the driving signals to the MPPT. A PC is used for data acquisition, running the control algorithm, data storage, as well as data display and analysis. The system has been implemented and tested under various operating conditions. The experimental results showed that the PV system with MPPT always tracks the peak power point of the PV module under various operating conditions. The MPPT transmits about 97% of the actual maximum power generated by the PV module. The MPPT not only increases the power from the PV module to the load, but also maintains longer operating periods for the PV system. The air velocity and the air mass flow rate of the mechanical load are increased considerably, due to the increase of the PV system power. It is also found that, the increase in the output energy due to using the MPPT is about 45.2% for a clear sunny day.

Analytical model for predicting the performance of photovoltaic array coupled with a wind turbine in a stand-alone renewable energy system based on hydrogen

We present the results of an analysis of the performance of a photovoltaic array that complement the power output of a wind turbine generator in a stand-alone renewable energy system based on hydrogen production for long-term energy storage. The procedure for estimating hourly solar radiation, for a clear sunny day, from the daily average solar insolation is also given. The photovoltaic array power output and its effective contribution to the load as well as to the energy storage have been determined by using the solar radiation usability concept. The excess and deficit of electrical energy produced from the renewable energy sources, with respect to the load, govern the effective energy management of the system and dictate the operation of an electrolyser and a fuel cell generator. This performance analysis is necessary to determine the effective contribution from the photovoltaic array and the wind turbine generator and their contribution to the load as well as for energy storage.

Thermal performance of a solar pressure cooker based on evacuated tube solar collector

This paper presents the thermal performance of a community type solar pressure cooker based on evacuated tube solar collector. The developed design of solar pressure cooker has separate parts for energy collection and cooking unit and both are coupled by heat exchanger. The paper has presented the performance results of experimental study conducted on solar pressure cooker and a simulation model has been developed for predicting the cooker performance under a variety of operating and climatic conditions. The theoretical model is validated against the experimental results. The obtained results have suggested a possibility of several batches of solar cooking on a clear sunny day under typical conditions of Delhi.