Total Aperture Research Articles

Risky Business: Predator Chemical Cues Mediate Morphological Changes in Freshwater Snails.

Many prey organisms respond to the nonconsumptive effects of predators by altering their physiology, morphology, and behavior. These inducible defenses can create refuges for prey by decreasing the likelihood of consumption by predators. Some prey, as in marine mollusks, have been shown to alter their morphology in response to the presence of size-limited predation. To extend this work, we exposed pointed campeloma snails (Campeloma decisum) to chemical cues from a natural predator, the rusty crayfish (Faxonius rusticus), to better understand how snail morphology changes under the threat of predation. The total force needed to crush shells, total shell length, aperture width, and total weight, along with changes to these 3 body measurements, were recorded for each individual and used to quantify morphological changes as a function of risk. Snails exposed to crayfish chemical cues had shells that required significantly more force to crush their shells than controls (P=0.023). Total shell length was greater in crayfish-exposed snails than in control snails (P=0.012), and snails in the crayfish treatment also showed significantly more change in shell length than control snails (P=0.007). Similarly, aperture width was significantly greater in exposed snails (P=0.011). However, exposed snails exhibited significantly less change in aperture width than controls (P=0.03). Finally, we found that snails exposed to crayfish weighed significantly more than snails in the control (P=0.008). Thus, the results of this study show that morphology of gastropods is altered in the presence of predators, and this may be an antipredator tactic directly related to predation risk.

Destructive effect of UV-C light radiation on lettuce growth: risk assessment of long time exposure

Ultraviolet C (UV-C) light technology employs a particular wavelength within the ultraviolet spectrum to deactivate microorganisms, utilizing radiation as its method. UV-C light possesses germicidal properties, effectively disrupting the DNA of microorganisms such as bacteria, viruses and various pathogens, thereby impeding their ability to replicate and induce illness. Additionally, UV-C could enhance the production of phytochemicals and prevent contamination in agricultural applications. However, overexposure to UV-C can cause safety issues, especially for operators handling its utilization in germicidal or sterilization applications. This study investigated the destructive effects of UV-C light on the morphology and chlorophyll content of lettuces exposed to various durations, aiming to assess the risks associated with prolonged exposure. The results showed that prolonged UV-C exposure affects morphological and chlorophyll content changes. The most damaging effect on lettuce morphology and chlorophyll content was found in the 2 h of UV-C exposure treatment. In the 2 h of UV-C exposure treatment, lettuce length was reduced from 6.01 ± 0.80 cm on day 2 to 5.55 ± 0.78 cm on day 3. The lowest fresh weight of lettuce was also found at 2 h of UV-C exposure treatment (4.32 ± 0.94 gr). In addition, the lowest total lettuce stomata aperture was found in 2 h of UV-C treatment (41 units). Furthermore, on day 4, after 2 h of UV-C exposure treatments, the chlorophyll a, chlorophyll b and total chlorophyll content in lettuces were found to be 1.59 ± 0.02 mg g−1 FW, 0.93 ± 0.02 mg g−1 FW and 2.52 ± 0.04 mg g−1 FW, respectively. Therefore, the most destructive effect of UV-C was found during 2 h of UV-C exposure treatment. These findings indicate the dangers of long-term UV-C exposure to lettuce. Practically, this could also have a negative impact on humans. The knowledge gleaned from these findings is useful for safety issues in the industrial application of UV-C.

A comparative performance analysis of sensible thermal energy storage (with concentrated solar field and sCO2 Brayton Cycle) and hydrogen energy storage (with solar PV field)

Utility scale energy storage is an integral part of renewable energy installations to achieve sustainable and reliable transition to a net zero energy economy. There exists a myriad of such storage solutions each having unique characteristics. This paper attempts at a systems level quantitative study and comparison between two different energy storage technologies, Thermal Energy Storage System (TESS) which is already mature, and Hydrogen Energy Storage System (HESS) which gained a lot of momentum recently, with the former coupled with a concentrated parabolic trough solar field using molten salt as heat transfer fluid and a power block running on high efficiency sCO2 Brayton cycle while the latter is coupled with a solar photovoltaic (PV) field. So that comparisons can be made on similar scale, both the systems are normalized on the total equipment area used for capturing incident solar irradiation, i.e., total aperture area for the PTC field and total flat surface area of PV modules. Both the systems are subjected to year-long variations of ambient conditions and solar irradiance and off-design performances are simulated over various seasons. The results show superior performance of TESS in terms of roundtrip efficiency (96% as opposed to 32% with HESS) which also results in superior capacity utilization factor (CUF of 64.5% and 48% for TESS and HESS respectively) and better specific energy and energy density. However, HESS offers virtually infinite idling time where TESS has a shorter self-discharge time (17 h), and better power performance (specific power and power density) in 10MWe output range.

Optimal pattern synthesis of circular antenna arrays with improved effective aperture and beam area

Abstract Circular antenna array (CAA) is one of the most widely used antenna array designs. This paper addresses the design challenges of the CAA with the non-uniform single ring, which is placed in an X-Y plane with the best sidelobe level (SLL) and improved first null beamwidth (FNBW). It has been solved using differential evolution, craziness-based particle swarm optimization (CRPSO), and novel particle swarm optimization (NPSO) techniques. An optimal combination of feeding current and inter-element spacing provides an array pattern with the best SLL and improved FNBW, as well as some other parameter calculations of the antenna array like maximum directivity, maximum effective aperture, total effective aperture, maximum beam area, total beam area, circumference, and radius of the CAAs using these techniques. There are six designs of CAAs with different antenna elements (i.e., 10-, 12-, 16-, 20-, 36-, and 64-elements) which have been taken into account. Simulations are done in MATLAB. Based on various simulation results, we can analyze the performance of SLL and FNBW with other parameters using NPSO and compare them with different techniques of CAAs, as shown in the numerical analysis and simulation result section.

Curved toroidal row column addressed transducer for 3D ultrafast ultrasound imaging.

3D Imaging of the human heart at high frame rate is of major interest for various clinical applications. Electronic complexity and cost has prevented the dissemination of 3D ultrafast imaging into the clinic. Row column addressed (RCA) transducers provide volumetric imaging at ultrafast frame rate by using a low electronic channel count, but current models are ill-suited for transthoracic cardiac imaging due to field-of-view limitations. In this study, we proposed a mechanically curved RCA with an aperture adapted for transthoracic cardiac imaging (24 × 16 mm²). The RCA has a toroidal curved surface of 96 elements along columns (curvature radius rC = 4.47 cm) and 64 elements along rows (curvature radius rR = 3 cm). We implemented delay and sum beamforming with an analytical calculation of the propagation of a toroidal wave which was validated using simulations (Field II). The imaging performance was evaluated on a calibrated phantom. Experimental 3D imaging was achieved up to 12 cm deep with a total angular aperture of 30° for both lateral dimensions. The Contrast-to-Noise ratio increased by 12 dB from 2 to 128 virtual sources. Then, 3D Ultrasound Localization Microscopy (ULM) was characterized in a sub-wavelength tube diameter. Finally, 3D ULM was demonstrated on a perfused ex-vivo swine heart to image the coronary microcirculation.

Experimental assessment of a solar photovoltaic-thermal system in a livestock farm in Italy

This paper presents an experimental evaluation of the performance of a solar photovoltaic-thermal (PVT) system in a swine farm at Mirandola in Italy. In this project named RES4LIVE, funded by the EU’s Horizon 2020 program, a PVT system is installed to replace fossil fuel consumption in one of the barns on the farm. The electrical energy from the collectors is utilized to operate the heat pump and provide electricity to the barn, whereas the thermal energy from the collector is stored in a borehole thermal energy storage (BTES) for further use by a 35 kW heat pump. The hybrid solar field consists of 24 covered PVT flat plate collectors (7.68 kWel and 25 kWth) with a total aperture area of 39.3 m2, which can increase the temperature of the heat transfer fluid (HTF) to up to 40 °C. The PVT system is connected to a modular solar central (SC) with a standardized design that can also be used for other similar applications. The hybrid solar system complemented by energy storage is expected to save approximately 20,850 kg CO2/year. The data collected from the PVT system, SC, and BTES are rigorously analyzed to evaluate its overall performance. A comprehensive performance assessment reveals the capability of the solar system to reduce carbon emissions and effectively replace fossil fuel consumption in the agricultural sector.

Refractive Fresnel liquid crystal lenses driven by two voltages.

We propose and demonstrate a high-performance refractive Fresnel liquid crystal (LC) lens with a simple electrode design. The interconnected circular electrodes enable the creation of a parabolic voltage distribution within each Fresnel zone using only two driving voltages. By controlling these voltages within the linear response region of LC material, the desired parabolic phase profile can be achieved. We provide a detailed discussion on the electrode structure design methodology and operating principles of the lens. In our experiments, we constructed a four-zone Fresnel LC lens with a total aperture of 8 mm. The results show that the optical power of the lens can be continuously adjusted from -1.30 D to +1.33 D. Throughout the process of electrically tuning the optical power, the phase distribution within each Fresnel zone maintains a parabolic profile. These results demonstrate the high-performance of the proposed Fresnel LC lens.

Monte-carlo simulation of the effective lunar aperture for detection of ultra-high energy neutrinos with LOFAR

Ultra-high-energy (UHE) cosmic neutrinos interacting with the Moon’s regolith generate particle showers that emit Askaryan radiation. This radiation can be observed from the Earth using ground-based radio telescopes like LOFAR. We simulate the effective detection aperture for UHE neutrinos hitting the Moon. Under the same assumptions, results from this work are in good agreement with previous analytic parameterizations and Monte Carlo codes. The dependence of the effective detection aperture on the observing parameters, such as observing frequency and minimum detection threshold, and lunar characteristics like surface topography have been studied. Using a Monte Carlo simulation, we find that the detectable neutrino energy threshold is lowered when we include a realistic treatment of the inelasticity, transmission coefficient, and surface roughness. Lunar surface roughness at large scales enhances the total aperture for higher observation frequencies (ν≥1GHz\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ u \\ge 1~\ extrm{GHz}$$\\end{document}) but has no significant effect on the LOFAR aperture. However, roughness at scales small compared to the wavelength reduces the aperture at all frequencies.

Designed Structures of Interdigital Electrodes for Thin Film SAW Devices.

This paper studied the impact of the microstructure of interdigital electrodes on the performance of surface acoustic wave (SAW) resonators and proposed an innovative piston, dummy finger and tilt (PDT) structure, which was then applied to the GLONASS L3 band filters. Through the adoption of 3D finite element simulation (FEM), photolithography, and testing on an incredible high-performance surface acoustic wave (I.H.P. SAW) substrate, it is concluded that the total aperture length is 20T (T is period), resulting in a more optimal resonator performance; changing the width and length of the piston can suppress transverse modes spurious, but it does not enhance impedance ratio; to further improve the quality of the SAW resonator, the proposed PDT structure has been experimentally proven to not only effectively suppress transverse modes spurious but also possess a high impedance ratio. By utilizing a PDT structure within a "T + π" topology circuit, we successfully designed and manufactured a GLONASS L3 band filter with a bandwidth of 8 MHz and an insertion loss of 3.73 dB. The design of these resonators and filters can be applied to the construction of SAW filters in similar frequency bands such as BeiDou B2 band or GPS L2/L5 band.

Colocated MIMO Radar Waveform-Array Joint Optimization for Sparse Array.

Colocated multiple-input multiple-output (MIMO) radar can transmit a group of distinct waveforms via its colocated transmit antennas and the waveform diversity leads to several advantages in contrast to conventional phased-array radar. The performance depends highly on the degrees available, and element spacing can be deemed as another source of degrees of freedom. In this paper, we study the joint waveform and element spacing optimization problem. A joint waveform and array optimization criterion is proposed to match the transmit beampattern, the suppression range, and the angular sidelobes, under the constraints of minimal element spacing and total array aperture. Meanwhile, the effect of receive beamforming on suppressing mutual correlation between returns from different spatial directions is also incorporated into the optimization criterion. The optimization problem is solved by the sequential quadratic programming algorithm. Numerical results indicate that with more degrees of freedom from array spacings, colocated MIMO radar achieves a better transmit beampattern matching performance and a lower sidelobe level, compared with a fixed half-wavelength spaced array, but the benefits from additional degrees of freedom from array spacing optimization have a limit.

Inkjet-printed P(VDF-TrFE) film for high-frequency annular array.

An innovative processing to deposit P(VDF-TrFE) film on silicon wafers by an inkjet printing method was used to fabricate high-frequency annular array prototype. This prototype has a total aperture of 7.3 mm and 8 active elements. A polymer-based lens with low acoustic attenuation was added to the flat deposition on the wafer, setting the geometric focus to 13.8 mm. With a thickness of around 11 μm, the electromechanical performance of P(VDF-TrFE) films was evaluated with an effective thickness coupling factor of 22%. Electronics allowing all elements to simultaneously emit as a single element transducer was developed. In reception, a dynamic focusing, based on eight independent amplifying channels, was preferred. The center frequency of the prototype was 21.3 MHz, the insertion loss was 48.5 dB and the -6 dB fractional bandwidth was 143%. The trade-off sensitivity/bandwidth has rather favored the large bandwidth. Dynamic focusing on reception was applied and allowed to improvements in the lateral-full width at half maximum as shown on images obtained with a wire phantom at several depths. The next step, for a fully operational multi-element transducer, will be to achieve a significant increase of the acoustic attenuation in the silicon wafer.

Assessing machine independence of quantitative ultrasonography to evaluate vision degrading myodesopsia

Vision degrading myodesopsia (VDM) results from clinically significant vitreous opacities that reduce contrast sensitivity (CS) and visual quality of life (VQOL). Previous studies with a single clinical system for quantitative ultrasonography (QUS) found correlations with CS and VQOL as measured by the N.E.I. Visual Function Questionnaire (VFQ). Here, we evaluated a cohort of patients to determine if VDM as evaluated by QUS is machine independent. 28 eyes from 14 patients (age 56 ± 14 years) experiencing VDM were scanned with two different clinical ophthalmic ultrasound systems in succession: one with a 15-MHz single element transducer (23mm focal length, 7 mm aperture) and one with a 20 MHz annular array (five elements, 22 mm focal length, 9 mm total aperture). Images were acquired as a longitudinal plane through premacular vitreous in temporal gaze. Three QUS parameters and a composite score were computed from the vitreous region within each set of log-compressed envelope data and averaged over artifact-free frames. A linear regression comparing QUS parameters computed fromeach system showed statistically significant correlations (R ≥ 0.86, p < 0.001). Moreover, QUS parameters from both systems were correlated with CS and VFQ scores. The results from this study suggest the QUS parameters are independent of scanner and could be universally applied to assess VDM.

Performance analysis of coherent DPSK SIMO laser-based satellite-to-ground communication link over weak-to-strong turbulence channels considering Kolmogorov and non-Kolmogorov spectrum models

The performance of satellite-to-ground laser-based communication links is highly affected by atmospheric turbulence. Coherent detection with spatial diversity at the ground station receiver can mitigate the scintillation effects caused by atmospheric turbulence. Traditionally, the scintillation effects are modeled based on the Kolmogorov spectrum model. However, the experiments have indicated that scintillation effects on the laser beam propagation have non-Kolmogorov properties. Our goal in the present work is to analyze the average bit error rate (BER), outage probability (OP), and ergodic capacity of the satellite-to-ground heterodyne optical communication system with receiver spatial diversity. A differential phase-shift keying modulation technique is considered in this work. The propagated laser signal from the satellite to the ground station is assumed to be subjected to Málaga-distributed atmospheric turbulence. The atmospheric turbulence statistics are carried out based on the conventional Kolmogorov spectrum model and the three-layer altitude (TLA) non-Kolmogorov spectrum model. The performance of popular diversity combining techniques, namely, maximum ratio combining (MRC) and equal gain combining (EGC) techniques are analyzed. The statistical models of the MRC technique under the Málaga-distributed atmospheric channel model are obtained in analytical form expressions. The statistical models of the EGC technique under the Málaga-distributed atmospheric channel model are obtained via the fast Fourier transform representation of the characteristic function method. Based on these statistical models, average BER, OP, and ergodic capacity expressions for each type of diversity combining technique are derived. For the communication system under investigation, the performance of MRC and EGC multiple aperture receiver systems are compared to a single aperture receiver with the same total aperture area. These comparisons are carried out under the same conditions in terms of zenith angle and signal-to-noise ratio. The obtained results show that the performance of the optical communication system under investigation with MRC and EGC receivers can be improved by increasing the order of diversity. In addition, it is found that the difference in the performance between Kolmogorov and TLA non-Kolmogorov spectrum models is not significant at low zenith angles, while this difference increases as the zenith angle increases. All numerical results are verified by Monte-Carlo simulations.

Study on Denitration Performance of Mn-Ce/TiO2 Low-Temperature SCR Catalyst

Low sintering flue gas temperatures and large temperature fluctuations require the development of low-temperature and efficient SCR (selective catalytic reduction) catalysts suitable for the sintering process. It has been shown that modified Mn-Ce/TiO2 catalysts have good denitration capability and have potential commercial use. In this experiment, TiO2-loaded Mn and Ce SCR catalysts were prepared using the impregnation method, and a series of characterizations of the samples were carried out to illustrate the effect of the active material on the denitration efficiency. The kinetic analysis provides theoretical as well as data support for the subsequent optimization of the SCR catalysts. The results show that the denitration efficiency of the catalysts can reach 93.86% when the Mn content is 10% and the Ce content is 3%. The doping of active substances can increase the specific surface area, total pore volume and average aperture of the catalysts and improve the adsorption capacity of the catalysts.

Measurement of nasal anterior aperture and choana by computed tomography in newborns and infants

Nasal obstruction is potentially severe when it affects neonates because nasal breathing is predominant during this period. An accurate assessment of nasal airway obstruction should be based on a comparison of the patient's nasal cavity dimensions with precise "normal values". For this reason, we aimed in this study to evaluate the nasal morphometry in newborns and infants with Computed Tomography (CT) in our region. CT images of 134 children who had no facial and cranial anomalies and no pathology were evaluated. In the axial section, the total choana width, right lateral width of the choana, left lateral width of the nasal cavity, the posterior width of the vomer, total aperture width (AW), right aperture width (RAW) and left aperture width were measured in all participants. The study group was divided into 4 age categories: 0-30 days, 31-90 days, 91-180 days and 181-360 days. When the choanal measurements of the groups were evaluated, there was a significant difference between the groups in the choanal measurements (p<0.05, for all), but no difference was observed between the groups in terms of vomer measurements. While there was a significant difference between the groups in terms of AW measurement, there was a significant difference only between Group 1 and Group 4 in terms of RAW value. There was also a positive correlation between age and choanal and aperture values (p<0.05 for all), while no correlation was observed with vomer measurements The normal widths of the choanal and anterior nasal aperture in infants in our region were defined according to months and gender in our study. Considering that there may be social differences, knowing the normative values in normal healthy individuals is of great importance in the evaluation of clinical and pathological conditions.

Improving indoor air quality in primary school buildings through optimized apertures and classroom furniture layouts

This study aimed to examine the influences of the opened to total aperture area (the O/A ratio) and furniture arrangements in a naturally ventilated classroom’s internal ventilation and PM 2.5 deposition. For the experiments, four cases were established for the O/A ratio and layout. Computational fluid dynamics (CFDs) was validated and applied, using the ANSYS Fluent software, to determine the velocity and concentration of PM 2.5 in the primary school classroom. The results indicated that different furniture arrangements and O/A ratios affected the air velocities and PM 2.5 concentrations, and could improve indoor air quality. The furniture arrangement affected the PM 2.5 concentration at a height of 0–1.6 m, and concentrations at the inlet and outlet, as well as near the classroom wall, which were higher than that in the center. The U-shaped layout reduced the concentrations of PM 2.5 and the natural air in the classroom, yielding a minimum vertex in the middle of the classroom, particularly in the breathing zone of elementary students. Moreover, the indoor PM 2.5 concentration increased, with an increasing ratio of apertures in the classroom. An O/A ratio of 1 corresponded to the highest air velocity and PM 2.5 concentration in the classroom, with high turbulence in the middle. A ratio of 0.25 corresponded to the least PM 2.5 concentration in the classroom, particularly at below 2 m. Thus, applying the optimized results, an O/A ratio of 0.25 and the U-shaped furniture layout, to a classroom significantly lowered its PM 2.5 concentrations. • Primary school students are severely affected by air pollution in Chiang Mai. • Inexpensive and facile strategies necessary for reducing the PM2.5 concentrations. • Effects of the O/A ratio and furniture layouts on PM2.5 deposition are studied. • Computational fluid dynamics was applied employing the Ansys Fluent software. • Optimized results significantly lowered the PM2.5 concentrations of the room.

Dual circular polarization 2 × 2 slot array antenna based on printed ridge gap waveguide technology in Ka band

In this paper a novel multi-layer slot array antenna based on printed ridge gap waveguide (PRGW) technology with dual circular polarization (CP) at Ka band is proposed. This antenna consists of five layers, two dielectric substrates as a transition from PRGW to coax line and a branch line coupler (BLC) as an antenna feeding network, and three metal layers as a coupling slot, 2 × 2-element slot array antenna and ground layer. Feeding network has two individual ports consists of a BLC that based on PRGW implemented. The operating frequency band of the antenna for S11 < −10 dB with the gain more than 11.5 dBi is 27–29 GHz which covers the 27.5–28.35 GHz band proposed by Federal Communications Commission (FCC) and can be a suitable antenna for 5G applications at this frequency band. Total aperture size of the array antenna is less than 1.15 × 1.15 λ2 at 28 GHz and total efficiency of it is better than 80 %. Two individual ports of the proposed antenna provide two isolated left- and right-hand CP with axial ratio (AR) less than 2 dB for each port in aforementioned frequency range, and the measured results indicated that the antenna can provide isolation more than 15 dB between two input ports.

Development of a Miniature Embedded Imaging System For Internal Flow Measurements

Through this work, the foundation has been laid for the development of a system for small-scale, integrated, image- based flow diagnostics for ground and flight tests. This system addresses many of the challenges associated with alternative methods of performing these measurements. For this work a 120 fps imager was embedded in the ceiling of a Mach 2.0 wind tunnel to perform oblique shock impingement measurements. Illumination was provided via a ring-light system of micro-LEDs embedded around the camera lens aperture. The entire system was controlled using a Raspberry Pi 4 Model B to capture and process image data. The integrated system possesses a total aperture diameter of 20 mm. Pressure sensitive paint and UV oil flow visualization experiments capturing an oblique shock/boundary layer interaction were performed using this system.

A More Drought Resistant Stem Xylem of Southern Highbush Than Rabbiteye Blueberry Is Linked to Its Anatomy

Increasing extreme drought events due to climate change may cause severe damage to blueberry industries, including decreased fruit yield and quality. Previous studies on drought tolerance of blueberries focus mainly on functional changes of leaves, while hydraulic properties of blueberry stems related to drought resistance are poorly reported. Here, both xylem anatomical and functional traits of stems of two southern highbush (SHB) and three rabbiteye blueberry (REB) cultivars were investigated. Compared with REB, SHB showed lower sapwood hydraulic conductivity (KS) and P50 (xylem water potential with 50% embolism in xylem), suggesting that SHB has less conductive but safer xylem than REB. The hydraulic functional differences between two blueberry xylems were highly related to their significant differences in vessel anatomy. Small vessel diameter and total inner pit aperture area per vessel area (APA) limited the hydraulic conductivity of SHB xylem, but high conduit wall reinforcement, wood density, and vessel-grouping index in SHB xylem showed strong mechanical support and safe water transport. Besides, pseudo-tori pit membranes were found in all five cultivars, while the similar thickness of homogenous pit membrane in two blueberry species was not linked to other functional traits, which may be due to its limited measurements. These results reveal a trade-off between the water transport efficiency and safety in the blueberry xylem and clarify the variance of stem drought resistance in different cultivars from a hydraulic perspective. Further studies with such a perspective on other organs of blueberries are required to understand the drought tolerance of a whole plant, which builds a solid foundation for the introduction, cultivation, and management of blueberry industries.

Development and investigative studies on solar hot case food warmer for food safety at offices/institutes.

The paper presents the design, development and investigative studies into the use of a solar hot case/food warmer. The solar hot case can prove to be highly useful to the persons who carry hot food to their workplaces for lunch and eat it 4-5 h later. It can help keep food warm and infection free, by maintaining the food at an elevated temperature. The solar hot case has been developed with a total aperture area of 0.673 m2. The energy requirements for food warming have been calculated and found to be around 62 kJ in summer and 90 kJ in winter for an average lunch box of mass 0.25 kg containing 0.4 kg of food. The design of the solar hot case has been prepared on the basis of the food warming calculations to allow around ten lunch boxes to be warmed simultaneously. A computer program based on the solar radiation geometry and an ASHRAE model has been prepared to study the energy available in various months and to estimate the solar energy interception by the solar hot case. The results show that the energy absorbed by the system at an instant varies from around 300 to 1400 kJ/m2h in winter and 1000-2000 kJ/m2h in summer. Experimental in-field observations related to the temperature profiles of the developed system are also reported.