Window Design Research Articles

Incident-side-dependent mirror based on 1D photonic crystals containing VO2 nanoparticles

The optical properties of an incident-side-dependent mirror based on a one-dimensional photonic crystal composed of nanocomposite layers containing vanadium dioxide nanoparticles were investigated theoretically using the transfer matrix method in the near-infrared spectral range. The influence of the incident angle and filling fraction of the vanadium dioxide nanoparticles on the reflectance and transmittance of the structure were studied. We found that the mirror is an incident-side-dependent reflector with nearly zero transmittance in the photonic bandgap regions. The incident-side-dependent properties of the mirror are more pronounced when the vanadium dioxide nanoparticles are in their metal phase. In addition, the mirror is a perfect reflector for incoming rays from one side and a perfect absorber for incoming rays from the opposite side. Such temperature-controlled and incident-dependent mirrors may find application in the design of various intelligent windows.

Microstructure evolution and tribological properties of (TiB+TiC)/Ti–6Al–4V composites fabricated via in situ laser-directed energy deposition of wire and powders in an underwater environment

Titanium-matrix composite-reinforced restored layers are used to repair cracks and dents on titanium alloy shells to impart the deposition layer with the same properties as the base metal. However, there are few studies on their underwater applications. Underwater laser-directed energy deposition is a rapidly-developing technique that shows great application potential for underwater restoration projects. This paper reports the effect of the Ti/(B+C) ratio on the microstructure and mechanical properties of a layer restored underwater using CWPLDED. The results showed that the ceramic-reinforced phase transitioned from a quasi-continuous mesh distribution to a multi-point distribution as the Ti/(B+C) ratio changed. The matrix grain was refined because the reinforcing phase promoted the non-spontaneous nucleation of β-Ti and α-Ti and limited grain growth during both solidification and solid-state phase transformation. The composite layer restored underwater had a maximum ultimate tensile strength of 1231.18 ± 6.37 MPa and a maximum yield strength of 1158.11 ± 8.71 MPa. When Ti: B: C = 3: 4: 4, the improved wear resistance of the restored layer was attributed to the higher microhardness caused by an increased precipitated phase content and Ti matrix grain refinement. When Ti: B: C = 3: 4: 1, the restored layer exhibited better wear resistance due to the excellent spatial configuration of the reinforced phase. The intrinsic relationship between the (B+C) content, reinforced phase space, and dry sliding wear performance was revealed. This provides a design window for preparing (TiB+TiC)/Ti64 composite restored layers with excellent comprehensive performance by CWPLDED and offers new insights for repairing titanium alloys underwater.

Tradeoff between mass sensitivity and performance in quasi-zero stiffness vibration isolators

Quasi-zero stiffness isolators are a promising technology to reduce vibration transmission over a large frequency range while maintaining passive operation and low cost. Many different types of QZS isolators have been demonstrated utilizing a variety of mechanical, pneumatic, and magnetic components. While some of these types have their own unique challenges, other challenges are more general. Two of these challenges are mass sensitivity and hysteresis in the load-deflection curve caused by snap-through buckling, friction, or structural damping. This work investigates the impact of force-deflection hysteresis on isolation performance through experimental techniques. Results show that increasing hysteresis reduces the mass sensitivity but worsens the isolation performance at low frequencies. A tradeoff must be made between these two aspects but can be overcome by shifting the QZS region to difference forces. A simple method to achieve this adaptability exists for certain types of QZS structures, therefore enabling a variety of practical applications within a certain design window.

Imaging dendritic spines in the hippocampus of a living mouse by 3D-stimulated emission depletion microscopy.

Stimulated emission depletion (STED) microscopy has been used to address a wide range of neurobiological questions in optically well-accessible samples, such as cell culture or brain slices. However, the application of STED to deeply embedded structures in the brain of living animals remains technically challenging. In previous work, we established chronic STED imaging in the hippocampus in vivo but the gain in spatial resolution was restricted to the lateral plane. In our study, we report on extending the gain in STED resolution into the optical axis to visualize dendritic spines in the hippocampus in vivo. Our approach is based on a spatial light modulator to shape the focal STED light intensity in all three dimensions and a conically shaped window that is compatible with an objective that has a long working distance and a high numerical aperture. We corrected distortions of the laser wavefront to optimize the shape of the bottle beam of the STED laser. We show how the new window design improves the STED point spread function and the spatial resolution using nanobeads. We then demonstrate the beneficial effects for 3D-STED microscopy of dendritic spines, visualized with an unprecedented level of detail in the hippocampus of a living mouse. We present a methodology to improve the axial resolution for STED microscopy in the deeply embedded hippocampus in vivo, facilitating longitudinal studies of neuroanatomical plasticity at the nanoscale in a wide range of (patho-)physiological contexts.

NiO junction termination extension for high-voltage (>3 kV) Ga2O3 devices

Edge termination is the enabling building block of power devices to exploit the high breakdown field of wide bandgap (WBG) and ultra-wide bandgap (UWBG) semiconductors. This work presents a heterogeneous junction termination extension (JTE) based on p-type nickel oxide (NiO) for gallium oxide (Ga2O3) devices. Distinct from prior JTEs usually made by implantation or etch, this NiO JTE is deposited on the surface of Ga2O3 by magnetron sputtering. The JTE consists of multiple NiO layers with various lengths to allow for a graded decrease in effective charge density away from the device active region. Moreover, this surface JTE has broad design window and process latitude, and its efficiency is drift-layer agnostic. The physics of this NiO JTE is validated by experimental applications into NiO/Ga2O3 p–n diodes fabricated on two Ga2O3 wafers with different doping concentrations. The JTE enables a breakdown voltage over 3.2 kV and a consistent parallel-plate junction field of 4.2 MV/cm in both devices, rendering a power figure of merit of 2.5–2.7 GW/cm2. These results show the great promise of the deposited JTE as a flexible, near ideal edge termination for WBG and UWBG devices, particularly those lacking high-quality homojunctions.

The Effect of Window Placement on Natural Ventilation Capability in a Jakarta High-Rise Building Unit

The purpose of this study was to investigate the natural ventilation potential in an apartment unit in a high-rise building. A corner unit of a two-bedroom apartment was selected for this study, where single-sided and cross ventilation occurred in the unit. This study employed a CFD simulation to model the indoor airflow of an apartment unit in West Jakarta. The units were modelled and simulated using CFD with a RANS k-ε turbulence model. The results were validated with the readings from the field measurements that had been conducted. Based on CFD results, the window position influences indoor airflow. In the case of cross ventilation, a windward opening is more beneficial, while in single-sided ventilation, a leeward opening creates more indoor airflow. Therefore, it is recommended that the characteristic of window design be considered in the early design stage not only to improve indoor air quality but also to maintain privacy and safety measures.

Fabrication of high-transmittance and fast-response bistable dual-frequency CLC cells

Liquid crystal devices are popularly used in the design of smart windows. However, the continuous electric field required for their operation may cause unnecessary energy loss and there is a risk of state transition when the electric field disappears. To overcome these problems, bistable devices were developed that exhibit electro-optic memory. In this study, we demonstrate the synthesis of a novel liquid crystalline acrylic chiral dopant. The polymerizable chiral dopant is expected to disperse and be fixed in liquid crystals, homogeneously revealing higher chiral efficiency. Incorporation of the synthesized chiral dopant into the dual frequency cholesteric liquid crystal results in a bistable display performance with a high transmittance of 97.6% and a fast response time of 1.5 ms. Each of the transparent “ON” and opaque “OFF” states was maintained without the bias of a continuous electric field. The achieved results show the possible application of the synthesized acrylic chiral dopant on a bistable dual frequency cholesteric liquid crystal display (BDFCLC) for smart windows and other devices. BackgroundThe continuous electric field required for their operation may cause unnecessary energy loss and there is a risk of state transition when the electric field disappears. MethodsTo fabricate a smart optical device with fast transition between “ON” and “OFF” states, and with continuously electric field addition, a new acrylic chiral dopant was synthesized and mixed with commercially available dual frequency nematic liquid crystal as a new cholesteric liquid crystal material possessing both perpendicular and planer arrangements with and without one-time electric field addition. Significant findingsIn this study, we demonstrate the synthesis of a novel liquid crystalline acrylic chiral dopant. The polymerizable chiral dopant is expected to disperse and be fixed in liquid crystals, homogeneously revealing higher chiral efficiency. Incorporation of the synthesized chiral dopant into the dual frequency cholesteric liquid crystal results in a bistable display performance with a high transmittance of 97.6% and a fast response time of 1.5 ms. Each of the transparent “ON” and opaque “OFF” states was maintained without the bias of a continuous electric field.

Daylighting performance and discomfort glare assessment of granular aerogel glazing system: A full-scale comparative experiment

Energy saving, natural lighting, and visual comfort are essential factors to be considered in window design. Granular aerogel glazing system (AGS) has great energy-saving potential, whereas the studies on daylighting performance, especially the visual comfort of AGS are very limited. In this study, a full-scale experiment was conducted to evaluate the daylighting performance and discomfort glare of AGS compared to that of the double-glazed system (DGS) in overcast and sunny days. The horizontal illuminance in the front, middle, and back positions, the vertical illuminance, and the illuminance uniformity were comprehensively analyzed. The high dynamic range (HDR) photograph technique was used and validated. The daylight glare probability (DGP) and daylight glare index (DGI) identified by the task area method, threshold method, and factor method were extracted from HDR images by Evalglare. The results showed that the average horizontal illuminance in the AGS test room is lower than that in the DGS test room. However, due to the scattering effect of AGS, the horizontal illuminance of the AGS test room may be higher than that of the DGS test room in positions where no direct sunlight directly hitting at noon in sunny days. The maximum increasing rate of the hourly horizontal illuminance in the middle and back positions of the AGS test room in September is 37.8% and 54.5%. It is also found that glare may occur in the AGS test room mainly due to excessive luminance. The discomfort glare in the AGS test room may be intolerable in sunny days.

View access index: The effects of geometric variables of window views on occupants’ satisfaction

One of the important aims of window design is to provide quality views that affect occupant health, well-being, and work performance. We assessed the effect of geometric variables (i.e., view angles, glazing area (Window-to-Wall Ratio, WWR), window distance, viewing direction and percentage of window view area in the visual field (PWV)) had on occupants’ satisfaction to view access. We conducted a human subject experiment with 40 participants using simulated images displayed in virtual reality headsets. Each participant rated 40 images with the geometric window view variables being presented in various combinations. The results showed that glazing area (WWR), window distance, and viewing direction were the three primary predictors for view access satisfaction. Based on the empirical results, we developed a view access index. This index found that satisfactory view access cannot be achieved with WWRs < ∼25%, and the level of satisfaction with view access did not increase substantially when WWRs > ∼65%. The proposed index is the first model that predicts occupant satisfaction to view access by considering the complex interplay of multiple geometric window view variables derived from an immersive environment. Given the impact of glazing area, window distance and viewing direction have on occupant satisfaction in the workplace, it is important to integrate them during the early stages of building design. For minimum view access requirements, we recommend WWRs and horizontal view angles that are greater than 25% and to 35°.

Multi-objective optimization design of energy efficiency for office building window systems based on indoor thermal comfort

Different window design schemes have different effects on heating, cooling, lighting energy consumption and indoor thermal comfort. This research established four scenarios, considering different window design variables, such as: window to wall ratio, glazing type, overhang and fin depth, maximum and minimum outdoor temperature setpoint for window opening and window opening factor, to minimize different energy consumption and thermal discomfortable hours. Sensitivity analysis was carried out prior to optimization to compare the sensitivity of each window design variable to different research objectives. Through optimization based on the non-dominated sorting genetic algorithm II (NSGA-II), the recommended values of each window design variable were given, designers can choose different optimal schemes according to preferences. Results in this paper are of great significance in guiding designers in the early design stage of office buildings.

Impact of Window Design on Dynamic Daylight Performance in an Office Building in Iran

Window design affects the building's appearance. Besides, it has a significant impact on daylight performance and the visual comfort of interior spaces. Therefore, choosing the shape and position of windows can be a challenge for architects. This research aims to investigate the impact of window design on dynamic daylight performance to enhance visual comfort. The research examines five common window shapes that are located in two different positions on the southern-facing side. The most common dynamic daylight metrics of LEED v4.1 were used to investigate the spatial daylight autonomy (sDA), and annual sunlight exposure (ASE). Furthermore, useful daylight illuminance (UDI) was considered a complementary approach to assess useful daylight levels. The metrics are examined in three cities including Mashhad, Isfahan, and Bandar Abbas, which are located in the northeast, center, and south of Iran, respectively. Thirty simulations in each city are conducted by Grasshopper Graphical editor as a parametric interface and its plugins, ladybug, and honeybee for dynamic daylight analysis. The results emphasize that window design has a significant impact on dynamic daylight performance. The square window meets the LEED needs in three cities by achieving maximum sDA and minimum ASE by up to 68.8% and 20% in both positions, respectively. Moreover, the centrally positioned square window presents the lowest ASE level of 14.4% among other cases. However, the windows in a higher position, especially horizontal windows obtain the highest values of sDA, UDI, and ASE by up to 77%, 59%, and 30%, respectively. Therefore, the ASE rates deteriorate by increasing the sill height and head height of windows. This paper can provide window design recommendations based on the comparison of dynamic daylight metrics for five common window shapes.

From the Mexican glass industry to the smart fabric: applications of advanced materials in window design

El presente trabajo de investigación pretende entender cómo el desarrollo tecnológico ha impactado el diseño y funcionalidad de una ventana tradicional. Se analiza la situación de la industria del vidrio como fuente original de este producto, y se enfatiza el papel del surgimiento de los materiales avanzados en el diseño de ventanas inteligentes dentro del ámbito arquitectónico y diseño de productos. Se incluyen ejemplos de ventanas comercializadas actualmente, así como un panorama en la industria mexicana y de investigación.

An 8-inch commercial aluminum nitride MEMS platform for the co-existence of Lamb wave and film bulk acoustic wave resonators

This work investigates a co-design approach for fundamental symmetric Lamb wave (S0) resonators (LWR) and film bulk acoustic wave resonators (FBAR) in a commercial 8-inch aluminum nitride (AlN) microelectromechanical system (MEMS) platform to enable multi-band operation. The platform utilizes surface micromachining to define local release cavities, providing an undercut-free solution for acoustic resonators to achieve a high quality factor (Q). However, being based on a standardized platform initially tailored for FBAR devices, many design considerations and trade-offs need to be investigated for the co-existence between LWR and FBAR design. Hence, to capture the optimal design window for S0 LWRs while analyzing its performance impact on existing FBARs, the electrode configuration and its thickness are thoroughly investigated by the finite element method. In this work, a 2.2 GHz FBAR, a 700 MHz S0 LWR, and a 2.19 GHz S0 Lamé LWR are demonstrated for performance evaluation across different types of devices in this platform. The measurement results revealed a baseline performance for the FBAR device with an electromechanical coupling factor () of 6.73% and Q of 3017 at 2.2 GHz, resulting in a high figure-of-merit (FoM = ) over 200. In comparison, the 700 MHz S0 LWR exhibits a high Q of 2532 as well and a of 1.1% (FoM = 27.8), while the 2.19 GHz S0 Lamé LWR also exhibits a high Q of 1752 and a of 2.44% (FoM = 42.7), respectively. These performance indexes are all comparable with the current state-of-the-art, revealing the excellent potential of this AlN MEMS platform being implemented for future LWR development design or even mass production.

Exploring view access for biophilic arctic architecture through immersive visualization of integrative lighting

This research addresses biophilic design opportunities in Arctic indoor environments through a comprehensive methodology that incorporates architectural features, extreme cold climate conditions, and integrative lighting attributes. The paper presents lighting and thermal conditions of higher latitudes and the potential challenges of biophilic window design in Arctic buildings. It discusses building standards and develops state-of-the-art techniques for analyzing quality views and lighting thresholds that support human health. It moreover proposes an innovative visualization framework to support decision-making in the design of indoor Arctic environments. A visualization process was developed and applied in environmental survey conducted through image-based and sensor-based techniques during an expedition in Iqaluktuuttiaq (Cambridge-Bay, 69°07′02″N 105°03′11″W), Nunavut in March 2020. The surveys combine the visualization of view access ratios in the 360° field of view (FOV), the intensity of melanopic/photopic luminance, and Equivalent Melanopic Lux (EML) through HDR imaging and radiometric measurements from several interior points at the Canadian High Arctic Research Station building. The paper also proposes 360° captures of surface temperatures as a compatible metric for the immersive visualization of physical ambiences in extreme cold climates. It compares view access ratios with human centric lighting potentials for 360° captures for each survey point. Results highlight the method's potential to support biophilic design in Arctic indoor spaces. It demonstrates how 360° FOV visualization of human responses to lighting conditions can provide a biophilic perspective of a space and its architectural properties.

High Optical Contrast of Quartet Dual-Band Electrochromic Device for Energy-Efficient Smart Window.

A quartet dual-band electrochromic device (ECD) was developed to selectively control the transmittance from the visible to near-infrared wavelengths for the application of an energy-efficient smart window. The new AgNO3+TBABr+LiClO4 (ATL)-based electrolyte was developed to independently control the redox reaction of lithium and silver ions to demonstrate the quartet mode of an ECD. A dual-band ECD with a sandwich structure was assembled using an ATL-based electrolyte, WO3 electrochromic layer, and antimony-doped tin oxide (ATO) ion storage layer. The employed WO3 and ATO films were fabricated using a nanoparticle deposition system (NPDS), a novel ecofriendly dry deposition method. Four modes, namely, transparent, warm, cool, and all-block modes, were demonstrated via an independent redox reaction of both lithium and silver ions through the simple control of the applied voltage. In the warm mode, the localized surface plasmon resonance effect was exploited by producing silver nanoparticles upon two-step voltage application. Furthermore, since the high surface roughness of the WO3 thin film fabricated by NPDS maximized the light scattering effect, 0% transmittance at all wavelengths was observed in the all-block mode. Dual-band ECD showed high optical contrasts of 73% and long-term durability over 1000 cycles with no degradation. Therefore, the possibility of controlling transmittance at the target wavelength was confirmed using a simple device with a simple process, suggesting a new strategy for the design of dual-band smart windows to reduce the energy consumption of buildings.

Optical Protective Window Design and Material Selection Issues in the Multi-Sensor Electro-Optical Surveillance Systems.

Multi-sensor imaging systems have a very important role and wide applications in surveillance and security systems. In many applications, it is necessary to use an optical protective window as an optical interface connecting the imaging sensor and object of interest's space; meanwhile an imaging sensor is mounted in a protective enclosure, providing separation from environmental conditions. Optical windows are often used in various optical and electro-optical systems, fulfilling different sometimes very unusual tasks. There are lots of examples in the literature that define optical window design for targeted applications. Through analysis of the various effects that follow optical window application in connection with imaging systems, we have suggested a simplified methodology and practical recommendation for how to define optical protective window specifications in multi-sensor imaging systems, using a system engineering approach. In addition, we have provided initial set of data and simplified calculation tools that can be used in initial analysis to provide proper window material selection and definition of the specifications of optical protective windows in multi-sensor systems. It is shown that although the optical window design seems as a simple task, it requires serious multidisciplinary approach.

Preparation and Characterization of Poly(Acrylic Acid)-Based Self-Healing Hydrogel for 3D Shape Fabrication via Extrusion-Based 3D Printing.

The three-dimensional (3D) printing of hydrogel is an issue of interest in various applications to build optimized 3D structured devices beyond 2D-shaped conventional structures such as film or mesh. The materials design for the hydrogel, as well as the resulting rheological properties, largely affect its applicability in extrusion-based 3D printing. Here, we prepared a new poly(acrylic acid)-based self-healing hydrogel by controlling the hydrogel design factors based on a defined material design window in terms of rheological properties for application in extrusion-based 3D printing. The hydrogel is designed with a poly(acrylic acid) main chain with a 1.0 mol% covalent crosslinker and 2.0 mol% dynamic crosslinker, and is successfully prepared based on radical polymerization utilizing ammonium persulfate as a thermal initiator. With the prepared poly(acrylic acid)-based hydrogel, self-healing characteristics, rheological characteristics, and 3D printing applicability are deeply investigated. The hydrogel spontaneously heals mechanical damage within 30 min and exhibits appropriate rheological characteristics, including G'~1075 Pa and tan δ~0.12, for extrusion-based 3D printing. Upon application in 3D printing, various 3D structures of hydrogel were successfully fabricated without showing structural deformation during the 3D printing process. Furthermore, the 3D-printed hydrogel structures exhibited excellent dimensional accuracy of the printed shape compared to the designed 3D structure.

Investigation into the effects of foaming variables on the cellular structure and expansion ratio of foamed TPU using response surface methodology

Thermoplastic polyurethane elastomer (TPU) foams were prepared using the high-pressure autoclave with supercritical fluid carbon dioxide (SC-CO2). The effects of foaming variables (i.e. saturation temperature, saturation pressure, and depressurization rate) on cellular structure and expansion ratio were investigated. The model between expansion ratio and foaming variables was constructed using the Box-Behnken design (BBD) of response surface methodology (RSM), and analysis of variance (ANOVA) was conducted to evaluate the validity and significance of the model. Finally, the interactive effects of foaming variables on the expansion ratio were investigated, and the expansion ratios of maximum and center point from numerical model were verified by experiment. The result showed higher saturation pressure and depressurization rate resulted in the more uniform cellular structure and higher cell density, however the higher saturation temperature resulted in the bigger cell and nonuniform structure. The ranges of average cell diameter and cell density were 15.26–45.4 μm and 0.32 × 108 to 6.24 × 108 cells/cm3, respectively. The model obtained using BBD of RSM was valid to predict the expansion ratio in the design window. The saturation temperature was the most important factor influencing the expansion ratio. With the increase of saturation temperature, the expansion ratio always increases in the design window. The maximum expansion ratio from numerical optimization was 4.91, which was located at saturation temperature 190°C, saturation pressure 12.51 MPa, and depressurization rate 5 MPa/s, and the corresponding experiment value was 4.56. The error between them was 7.13%.

DAYLIGHTING PERFORMANCE OF HIGH SCHOOL LEARNING ENVIRONMENT IN TROPICS

ABSTRACT The quality of the indoor environment, including the lighting conditions, is crucial in classrooms as it directly affects students’ learning performance and productivity. Natural light is the best light source for visual comfort, aesthetics, and energy efficiency. Malaysia is in a tropical region and has abundant daylight availability that could meet the required lighting during the day. However, in Malaysian schools, electric lights are frequently switched on during classes in the daytime; hence, daylighting is not efficiently utilised. This study investigates the daylighting performance in classrooms in a national high school in Penang, Malaysia. Fieldwork was conducted by measuring incident illumination levels inside selected classrooms in the Teluk Kumbar High School. The results show that average illumination levels were between 400 lux to 1000 lux, more than enough in most classrooms because of the relatively large windows with clear glass. The average daylight ratios recorded in the classrooms were between 6.4 and 9.2%, which may result in glare problems. Simulations were conducted using Design-Builder to further evaluate the annual daylighting performance including Daylight Autonomy (DA), Annual Sun Exposure (ASE) and Useful Daylight Illuminance (UDI). Based on the findings, it is recommended to use shading devices or replace the glazing type to improve daylighting performance for visual comfort. Proper design and selection of windows in schools can significantly improve indoor lighting quality for students and reduce solar heat gain.

Optimal sampling regimes for estimating predator-prey dynamics

Predator-prey models are often used in ecology to represent realistic encounters between species. Lotka-Volterra differential equations are famously used by ecologists to model the relationship between a predator and prey. Given ecological data collection is known to be time consuming and difficult, the purpose of this paper is to optimize the process and improve sampling efficiency. The method of sequential optimality is applied to a more complex population model with multiple basins of attraction, the Lotka-Volterra differential equations. In this application, various theoretical scenarios are simulated using varying sample sizes and timeframes to determine optimal designs. The first scenario uses a standard sample size and design window to represent a realistic budget for ecological data collection. The second scenario decreases the budget and extends the design window as a representation of a limited budget. The third scenario represents ample resources available for sampling. The three scenarios are used to then compare the optimal designs and help ecologists evaluate the method of sequential optimality. I, A and D optimal designs are compared in the simulation results. The I-optimality criterion tends to outperform the A and D criteria and is recommended as a primary selection when using the sequential optimality algorithm. This simulation study has further developed sequential optimality by predicting optimal sampling regimes according to the dynamics associated with the Lotka-Volterra differential equations.