Mirror Layout Research Articles

Fruit grading system by reconstructed 3D hyperspectral full-surface images

Conducting hyperspectral imaging of fruit' entire surfaces while simultaneously evaluating their physical properties, such as volume and mass, can provide a richer dataset for comprehensive fruit classification. For this purpose, a fruit grading system using 3D hyperspectral full-surface images is developed, which is based on multi-view imaging of mirrors in the hardware structure design and relies on the virtual volume intersection (VI) algorithm and texture technology in software design. During the design process, a mathematical model for the mirror layout and system geometry parameters is established to determine the system's layout for scanning the entire surface of the sample. In practical applications, a prototype with 28 channels ranging from 400 to 1000 nm is developed for pear samples based on a sub-component control system, a spherical-cap cavity with flashing multi-color LEDs, and multiple side mirrors. The results obtained from this prototype reveal that the predicted volume (R2=96.18%) and mass (R2=98.18%) exhibit a high correlation with measured results and the hyperspectral data between bruised and normal pears is a significant difference. A dataset of pears of three qualities (large, small, and bruised) is prepared for comprehensive classification and resulting in an effective grading (95.33%), which shows that the proposed system is a potential solution for comprehensive fruit quality classification.

Analysing and Designing Layout of all current mirrors on Cadence Virtuoso

Abstract: This paper proposes new current mirror layout strategies which are being designed using 180nm technologies using cadence virtuoso layout software. The performances of circuit is also being analysed in L edit window by varying input current and input voltages values or by changing arrangement of N- Type-Mosfet. Simulation results show a significant improvement in matching characteristics of the proposed structures over what is achievable with existing layout techniques in demanding applications.

Promote optical performance of linear Fresnel micro-concentrator by an offset-axis mirror layout in building-integrated PV/T application

In building integrated PV/T applications, the utilization of linear Fresnel micro-concentrators could promote solar energy harvesting efficiency. For the consideration of low wind load and building aesthetics, the height of the concentrator is invariably kept in a small range, resulting in severe optical blocking between mirrors. In this paper, two offset-axis mirror models are introduced to promote the optical efficiency of the micro-concentrator. The rotating axis of the mirror in the former model is not located on the symmetrical axis of the mirror but is offset to one side of the mirror. The later model is a rod offset-axis mirror with the axis offset to the outside of the mirror by a rod. These offset-axis mirrors allow the mirrors farther away from the receiver to possess a higher position for larger angular rotation, thus reducing the blocking between mirrors. Thereafter, mathematical models were established to obtain the key parameters of each mirror at different axis positions, and the influence of the axis position on the optical performance of the micro-concentrator was analyzed. The results revealed that both kinds of offset-axis mirrors could significantly improve the ground utilization ratio of the micro-concentrator and realize a more compact micro-concentrator design. In comparison with the layout scheme with the conventional central-axis mirrors, the ground utilization ratio of micro-concentrator with a hybrid layout of side-axis mirrors and rod offset-axis mirrors was improved by 28%. The optical simulations based on the Monte Carlo method revealed that a micro-concentrator with a hybrid layout of side-axis mirrors and rod offset-axis mirrors could promote the solar harvesting efficiency by 56.8% compared to the conventional central-axis mirror layout, regardless of direct normal sunlight or large angle inclined sunlight. The concept and calculation methodology of offset-axis mirror presented in this paper could reduce the thickness of linear Fresnel micro-concentrators in the design and improve their concentrating efficiency, which would lay the solid foundation for the wide application of micro-concentrators in the building domain.

Design and Performance of Ultraviolet 368-nm AlGaN-Based Flip-Chip High-Voltage LEDs with Epitaxial Indium Tin Oxide/Al Reflective Mirror and Symmetry Electrode Arrangement

In this letter, we describe the design and fabrication of high-power AlGaN-based ultraviolet (UV) flip-chip high-voltage light-emitting diodes (LEDs) operating at 368 nm with an epitaxial indium tin oxide (ITO)/Al reflecting mirror and symmetry electrode layout. Metal-organic chemical vapor deposition (MOCVD) was used to grow an ITO thin film as a transparent electrode on the LED surface. At 365 nm, epitaxial ITO thin films exhibited a transmittance of up to 93.6%. Additionally, the epitaxial ITO/Al reflective mirror has a reflectance of 81.2% at 365-nm. To investigate the electrical characteristics, four types of HV-LED micro-cells were constructed with varying n-type mesa structures and p-type interconnect electrodes. We demonstrated a forward voltage (Vf) of 7.86 V at 350 mA with a 2 × 2 mico-cells high-voltage ultraviolet 368-nm flip-chip LED after optimising electrode structure and device process.

Heliostat layout optimization for load-following solar tower plants

An optimization procedure to design the heliostat layout in Solar Tower plants is introduced in the present paper. Whilst typically the mirror layout generation aims to maximize the annual power production, the model presented in this work determines the optimal heliostat distribution when the overall efficiency is maximized (and the LCOE is minimized) for specific periods of the year. This is crucial for CSP plants operating in island mode or within isolated grids, where the power demand is variable throughout the year and massively concentrated in certain months, and the backup units have limited capacity. The study focuses on a solar field corresponding to a nominal power of 5 MWe.The optimization process allowed to determine radial spacing of the mirror rows, tower height and position of each single heliostat for three different design periods. The resulting layouts exhibit a maximum annual field efficiency ranging between 64.78% and 65.77%. Introducing the economic evaluation, 18.43 ¢USD/kWh is the best LCOE value achieved for the layouts designed for March conditions. Furthermore, the study shows that the fields optimized for June achieve the highest peak efficiency values, but the annual yield is better if March is considered as design period.

A comparative study of different optimised mirrors layouts of Linear Fresnel concentrators on annual energy and exergy efficiencies

This paper is aimed at investigating optimised mirror layout effects of Linear Fresnel Concentrators (LFC) by evaluating the annual energy and exergy efficiencies. Subsequently, a north–south central receiver LFC with cylindrical mirror profile and Trapezoidal Cavity Receiver (TCR) were considered. Two distinct mirrors reference configurations such as the sun and specific references and four different layouts such as the constant width and shift, constant width and variable shift, variable width and constant shift and variable width and variable shift studied separately and for each of them, the widths and shifts of mirrors optimised through an analytic method. A TCR was designed for every layout, and its heat loss was estimated from numerical modelling to derive the annual energy and exergy values. It was concluded that considered mirrors reference configurations and mirrors layouts play an important role in energy and exergy efficiencies. Furthermore, variable width layouts have a higher impact on energy and exergy amounts than variable shift layouts due to their effects on the receiver dimension and its heat loss. Finally, besides the highest efficiency of variable width and shift layout in specific reference, the constant and variable width layouts demonstrate superior performance in sun and specific references, respectively.

Lésions congénitales périorbitaires en miroir dites « kissing » : nævus ou tache café au lait ?

"Café au lait" spots (CLS) are pigmented skin lesions principally located at the trunk and the limbs. Histologically, CLSs consist in an excessive pigmentation of the epidermis, with no risk of malignant transformation. The "kissing" nevus is a rare pigmented congenital nevus affecting both lower and upper eyelids in a mirror layout. As other nevi, it presents a theoretical risk of malignant transformation. These two pigmented lesions are responsible for aesthetic discomfort when affecting the face. Three patients presenting with a congenital pigmented lesion affecting the two eyelids in a mirror layout are presented. In two cases, the lesions, initially considered as "kissing" nevi, were classified as CLSs. The diagnosis of CLS was made on a biopsy in one patient and after surgery in the other one. Pigmented mirror layout lesions, called "kissing" lesions, are exclusively described for the nevi. We describe two cases of CLSs affecting the eyelids in a mirror layout. Difficulties in diagnostic are exposed and the possible treatments are discussed.

An alternative methodology to treat solar radiation data for the optical efficiency estimate of different types of collectors

An alternative methodology to calculate the yearly optical efficiency of a generic solar power collector/converter for any chosen location is here proposed. The innovation is in considering the yearly direct normal irradiation (DNI) not as a series of temporal data with hourly or minute resolution, but rather, as a map of physical positions assumed by the sun during the year in the sky vault. A MATLAB® suite was developed to convert the temporal DNI information, which is usually available for a chosen location, into spatial DNI information. The suite allows creating a yearly direct solar irradiation density map as function of a generic pair of independent angular coordinates (e.g., azimuth and zenith). The yearly DNI density map can then easily be multiplied by the collector efficiency map to obtain its yearly optical efficiency. The main advantages of the proposed approach compared to conventional temporal ones are (i) reduced magnitude of computational effort, and (ii) ease in conducting collector optical optimization. The approach is tested on three cases—a generic flat collector and two linear collectors—to show its generality and potentialities. The developed methodology is applied to optimize the yearly optical efficiency of a linear Fresnel collector with different orientations and mirror layouts.

Analysis of solar shading caused by building-integrated Vertical Heliostat Fields

The “Vertical Heliostat Field” (VHF) concept proposes a solution to integrate solar heliostat fields in urban communities with the aim of deploying modular Concentrating Solar Power systems nearby populated areas. Its distinctive feature resides in the use of special mirror layouts where heliostats should be distributed on a vertical surface (i.e., a building façade). The VHF reflects radiation coming from the sun toward a common point where a solar receiver has been placed for power generation or other high temperature applications. This work presents the optical performance of the Vertical Heliostat Field as a shading system, studying the daylighting evolution inside the building as a function of VHF parameters (separation between heliostats, date, field zone, etc.), though always preserving the compatibility with the primary goal of achieving good performance and operational efficiencies as a solar thermal power plant comparable to a conventional central receiver system. Direct and diffuse components of solar radiation have been considered separately. Results indicate that a field with reduced spacing between heliostats provides a good performance as an element for shading building façades.

Solar radiation concentration features in Linear Fresnel Reflector arrays

This paper is aimed at characterizing the concentration process for LFRs, and to analyze the use of different optical designs, including circular-cylindrical and parabolic-cylindrical mirrors with different reference positions. A new approach to analyze and optimize the performance of Fresnel arrays is presented, which is based on a newly formulated optical property that can be used to evaluate the drift of the reflected sunbeams from the mirrors as they rotate to follow the sun. This new optical-geometric property sets upper bounds for the deviation of the reflected sunbeams, in relation to trajectories of the reference situation. It is observed that the maximum deviation depends on the width of the mirror, which must be limited for maximizing the optical efficiency. From this theory an optical design process is suggested to minimize such lateral drifts and to minimize the concentration factor variation along the day. A new mirror layout is defined for keeping a constant value of the radiation impinging onto the receiver from effective sunrise to effective sunset.

Parallel testing of multi-port static random access memories

This paper presents a novel approach for testing multi-port memories. This approach is based on the parallel execution of the testing process so that inter-port faults (shorts and coupling faults) can be detected at no loss of coverage and with no increase in the number of tests compared with a single-port memory. The parallelization is based on partitioning the memory into so-called segments; in each phase, the operation of a port is restricted to a segment. The proposed approach utilizes parallel segment accesses by arranging the ports on a pair-wise basis (one port for reading and the second port for writing); this permits an efficient utilization of the ports and full coverage of inter-port faults for both normal and mirror layouts. A port assignment process is utilized together with the partitioning of the memory; it considers the functionalities of the ports and their relation with respect to the addresses and the placement of the cells. It is shown that the test complexity of the proposed approach is independent of the number of ports. Simulation results are presented. A BIST circuitry capable of embedding and controlling this parallel approach is also proposed; it is shown that the BIST implementation is O(NlogN) where N is the number of ports.

Current Mirror Layout Strategies for Enhancing Matching Performance

This paper proposes new current mirror layout strategies to reduce the matching sensitivity to the linear parameter gradients. Effects of threshold gradients across a mirror on the matching characteristics of current mirrors are discussed. The performance of new and existing layouts are compared for threshold voltage gradients at arbitrary angles through the active area. Simulation results show a significant improvement in matching characteristics of the proposed structures over what is achievable with existing layout techniques in demanding applications.