Horizontal Modulation Research Articles

Accelerated generation of holograms with ultra-low memory symmetrically high-compressed look-up table

Computer-generated holography technology has been widely applied, and as research in this field deepens, the demand for memory and computational power in small AR and VR devices continues to increase. This paper presents a hologram generation method, i.e., a symmetrically high-compressed look-up table method, which can reduce memory usage by 50%. In offline computing, half of the basic horizontal and vertical modulation factors are stored, halving the memory requirements without affecting inline speed. Currently, its potential extends to various holographic applications, including the production of optical diffraction elements.

An exact method for machining lines design with equipment selection and line balancing

We consider the context of machining systems design where both equipment selection and line balancing decisions have to be taken in order to minimise the total cost of the system. The designed flow line employs multi-positional machines with rotary tables where vertical and horizontal machining modules can be used for the realisation of machining processes. For this challenging optimisation problem in production research, we develop an innovative mathematical model based on a mixed-integer linear programme and a heuristic algorithm for an approximate solution. An extensive numerical experiment is conducted in order to evaluate the performances of the proposed mathematical model and the developed heuristic. The obtained results show that the decision makers can use the elaborated methods for solving efficiently even large-scale industrial problems.

Design and Analysis of a Novel Wave Energy Harvester

A novel wave energy harvester (WEH) that can recover energy in the direction of heave, sway, and surge is designed under the background of low recovery efficiency and complex installation of the existing wave energy harvester. The harvester consisted of four main components: energy input module, energy transfer module, energy conversion module, and energy store module. In the paper, to convert more wave energy into electrical energy and improve the energy conversion efficiency of WEH, the motion transfer module is divided into vertical and horizontal motion transfer modules, which are used to harvest vertical and horizontal wave energy, respectively. The vertical motion transfer module combined with the ball screw structure, planetary gear structure, and one-way gear units ensure the generator has high speed. The horizontal motion transfer module is mainly composed of three uniformly distributed one-way gear units, ensuring collect the wave energy in all horizontal directions. The dynamic model of the harvester is established, and the simulation experiment is carried out under wave conditions with periods of 2 s, 2.5 s, and 3 s, respectively. The simulation results show that when the wave period is 2[Formula: see text]s, 2.5 s, and 3 s, the corresponding energy conversion efficiency of the WEH is 66.7%, 60.9%, and 57.1%, respectively. The proposed study provides a theoretical reference for modeling similar WEHs and can effectively balance energy supply and demand and further support the global agenda of UN-2030 for sustainable development, especially SDG-7.

Performance comparison of vertical and horizontal vacuum membrane distillation module coupled with mechanical vapor recompression

This paper focuses on the comparative study of vertical and horizontal vacuum membrane distillation (VMD) modules coupled with mechanical vapor recompression (MVR) system to obtain the optimal system layout structure and further improve operation stability and energy efficiency in the wastewater treatment. Firstly, freshwater accumulation characteristic in the vertical VMD module was explored under different working conditions. Then, comparative experiments of vertical and horizontal VMD-MVR systems were conducted. Finally, comprehensive performance of horizontal VMD-MVR system were evaluated. The obtained results showed that freshwater production in the distilling tank and freshwater accumulation in the VMD module were affected by operation time, feed temperature, feed flow rate, feed concentration and vacuum side pressure. Furthermore, the horizontal VMD-MVR system was proved to be a better choice due to lower freshwater accumulation in the VMD module and energy consumption in comparison to the vertical VMD-MVR system. Finally, long term operation experiment of 240 h indicated evaporation rate dropped to 55 kg/h as operation time reached to 180 h owing to membrane fouling. After membrane cleaning, evaporation rate recovered from 55 to 62 kg/h with a higher recovery efficiency of 95.1 %. Compared to conventional wastewater treatment systems, the horizontal VMD-MVR system exhibited excellent comprehensive performance.

P-y curves from in-situ ROBOCONE tests: a similarity approach for laterally loaded piles in clay

p-y curves from in-situ ROBOCONE tests: a similarity approach for laterally loaded piles in clay

Development of an innovative three-dimensional vibration isolation bearing

This paper presented an innovative three-dimensional vibration isolation bearing (3D-VIB) to mitigate horizontal seismic action and rail-induced vertical vibration. The 3D-VIB was composed of a thick laminated rubber bearing acting as the vertical vibration isolation module and a friction pendulum acting as the horizontal seismic isolation module. The thick laminated rubber bearing was used as a part of the slider in the friction pendulum. The compression performance of 3D-VIB was decoupled from its shear performance by concentrating the compressive deformation into the thick rubber bearing while shear deformation occurred independently in the friction pendulum module. The bearing capacity, vertical and horizontal properties of a full-scale 3D-VIB specimen were tested. In the test, the ultimate bearing capacity of 3D-VIB was 7 times that of the design compressive load of normal service condition. The vertical stiffness of the specimen under seismic vibration and vertical rail-induced vibration were tested separately. It was found that the vertical stiffness of the specimen under rail-induced vibration was 1.55 times higher than the vertical stiffness under seismic vibration. The horizontal performance of the 3D-VIB was characterized by stable parallelogram-shaped hysteretic curves similar to that of the traditional friction pendulum system. A user-defined element was developed and incorporated into ABAQUS to simulate the mechanical behavior of the 3D-VIB under different loading conditions, and simulation results agreed with the test results. The responses of a steel structure equipped with the 3D-VIB, while subjected to earthquake ground motions and rail-induced vibrations, respectively, were analyzed and compared with the non-isolated one. The analysis results suggested that with the installation of the 3D-VIB, the maximum inter-story drift ratio of the structure under maximum considered earthquake was reduced by about 88%. The average maximum transient vibration value of the rail-induced vertical vibration at the typical points of the conventional model was 86.2 dB, while that in the 3D-isolated model was 78.6 dB, the vibration reduction was 7.6 dB.

Convolutional symmetric compressed look-up-table method for 360° dynamic color 3D holographic display.

In this paper, we propose a convolutional symmetric compressed look-up-table (CSC-LUT) method to accelerate computer-generated hologram (CGH) computation based on the Fresnel diffraction theory and LUT. The proposed method can achieve one-time high-quality fast generation of color holograms by utilizing dynamic convolution operation, which is divided three processes. Firstly, the pre-calculated data of maximum horizontal modulation factor is compressed in 1D array by coordinate symmetry. Then, the test object is resampled to satisfy convolutional translation invariance. Finally, the dynamic convolution operation is used to simplify CGH computation process rather than the point-by-point computation. Numerical simulation and optical experimental results show that our proposed method can achieve faster computation speed, higher reconstruction quality and wider application compared to conventional SC-LUT method. The further optimization method for parallel acceleration on the GPU framework can achieve real-time (>24fps) color holographic display corresponding to three perspectives of a 3D scene.

Effect of perturbation timing on recovering whole-body angular momentum during very slow walking

Humans prioritize regulation of the whole-body angular momentum (WBAM) during walking. When perturbed, modulations of the moment arm of the ground reaction force (GRF) with respect to the centre of mass (CoM) assist in recovering WBAM. For sagittal-plane perturbations of the WBAM given at toe off right (TOR), horizontal GRF modulations and not centre of pressure (COP) modulations were mainly responsible for these moment arm modulations. In this study, we aimed to find whether the instant of perturbations affects the contributions of the GRF and/or CoP modulations to the moment arm changes, in balance recovery during very slow walking. Perturbations of the WBAM were applied at three different instants of the gait cycle, namely at TOR, mid-swing (MS), and heel strike right (HSR). Forces equal to 16% of the participant’s body weight were applied simultaneously to the pelvis and upper body in opposite directions for a duration of 150 ms. The results showed that the perturbation onset did not significantly affect the GRF moment arm modulation. However, the contribution of both the CoP and GRF modulation to the moment arm changes did change depending on the perturbation instant. After perturbations resulting in a forward pitch of the trunk a larger contribution was present from the CoP modulation when perturbations were given at MS or HSR, compared to perturbations at TOR. After backward pitch perturbations given at MS and HSR the CoP modulation counteracted the moment arm required for WBAM recovery. Therefore a larger contribution from the horizontal GRF was needed to direct the GRF posterior to the CoM and recover WBAM. In conclusion, the onset of WBAM perturbations does not affect the moment arm modulation needed for WBAM recovery, while it does affect the way CoP and GRF modulation contribute to that recovery.

A Hybrid Continuous-Time Dynamic Graph Representation Learning Model by Exploring Both Temporal and Repetitive Information

Recently, dynamic graph representation learning has attracted more and more attention from both academic and industrial communities due to its capabilities of capturing different real-world phenomena. For a dynamic graph represented as a sequence of timestamped events, there are two kinds of evolutionary essences: temporal and repetitive information. At present, the temporal information of interactions (e.g., timestamps) have been deeply explored. However, as another vital nature of dynamic graphs, the repetitive information of interactions between two nodes is neglected, which may lead to inaccurate node representation. To address this issue, we propose a novel continuous-time dynamic graph representation learning model, which consists of a node-level-memory based module, a historical high-order neighborhood based vertical aggregation module and a repetitive-topological information based horizontal aggregation module. In particular, to characterize the evolving pattern of the repetitive information of interactions between a pair of nodes, we put forward a repetitive-interaction based attention mechanism to integrate the two key attributes (i.e., the content and the number of interactions) of repetitive interactions at different moments, based on the insight that the repetitive behaviors of nodes are widespread and essential. We conduct extensive experiments including future link prediction tasks (for transductive and inductive learning) and dynamic node classification task, and results on three real-life dynamic graph datasets demonstrate that the proposed method significantly outperforms state-of-the-art baselines, for both observed nodes and new ones.

Bioinspired In‐Sensor Reservoir Computing for Self‐Adaptive Visual Recognition with Two‐Dimensional Dual‐Mode Phototransistors

AbstractArtificial visual systems that dynamically process spatiotemporal optoelectronic signals under complex real‐life environments bear a wide spectrum of edge applications. Despite significant progress in optoelectronic sensors and neuromorphic computing algorithms, developing visual systems that can adapt to a broad illumination range while retaining high performance, high efficiency, and low training costs remains a challenge. Here, this work reports a bioinspired in‐sensor reservoir computing (RC) for self‐adaptive visual recognition. By leveraging voltage‐tunable photoresponses of the MoS2‐based phototransistor array, the RC system demonstrates both scotopic and photopic adaptation functions and maintains a recognition accuracy of 91%. The horizontal modulation (HM) block enables the reservoir to adapt automatically in real‐time under changing illumination conditions, yielding a 90.64% recognition accuracy (14.21% improvement over conventional RC systems). These results pave the way for the emergence of a reconfigurable in‐sensor RC system with broad applications and enhanced performance for an efficient artificial vision system at the edge.

Development and validation of a concise and anisotropic irradiance model for bifacial photovoltaic modules

The irradiance model is significant for accurately modelling the electrical and thermal performance of bifacial photovoltaic (bPV) modules, but existing irradiance models fail to be employed for bPV modules in a simple but reliable way. Therefore, this paper presented a concise and anisotropic irradiance model to predict the irradiance received by bPV modules, in which an improved view factor-based model was adopted to calculate the ground-reflected irradiance. In addition to its computational simplicity, the proposed model can satisfy the assumption of an anisotropic irradiance at both sides of the horizontal, tilted, and vertical bPV modules. Outdoor experiments were conducted to validate the proposed model under different conditions. Results show that the proposed model can well predict the irradiance of bPV modules placed above a concrete ground. The prediction errors of the front/rear/total irradiance are 7.1%/12.5%/6.1% and 11.9%/16.5%/8.7% for tilted and vertical bPV modules, respectively. In addition, the prediction performance decreases when a high-reflective ground made of aluminum foil is used. It is found that the albedo of the high-reflective ground will vary significantly on sunny days, mainly due to the incident-angle dependence of the ground reflection. Grounds with more diffuse reflections can improve the accuracy of the model's predictions.

Demonstration of 12 Years Outdoor Working of Highly Durable Dye-Sensitized Solar Cell Modules Employing Hydrophobic Surface Passivation and Suppression of Biased Distribution of Iodine Ions

Dye-sensitized solar cells (DSCs) outperform conventional silicon solar cells in terms of weight and design flexibility. Therefore, besides standard rooftop installation, DSCs are suitable for new applications, including windows and walls. However, insufficient durability remains a critical issue, and outdoor working over 10 years is yet to be realized. In this study, we developed two approaches to improve the durability. The first involves hydrophobic surface passivation on the TiO2 surfaces by adopting alkylbenzimidazole (CnH2n+1BI) with long alkyl chains instead of the conventional additive (N-methylbenzimidazole) used for high open-circuit voltage in an ionic liquid-based electrolyte. The additive with a suitable alkyl-chain length (N-butylbenzimidazole and N-hexylbenzimidazole) notably improved the resistance against infiltrating water. The second approach refers to the DSC module arrangement. A unique problem of large-sized modules is that the I3– distribution often becomes biased over time, lowering the conversion efficiency. Horizontal module arrangements and/or the strip-shaped single cells in the modules solved this problem. By adopting these two approaches, we have demonstrated that the 10 cm × 11 cm-sized DSC modules have high durability to maintain 75% of their initial performance after the 12 year outdoor working test. This is the longest demonstrated lifetime for DSC modules outdoors.

Modeling multi-type urban landscape dynamics along the horizontal and vertical dimensions

Fine-scale urban simulation obtained through vector-based cellular automata (VCA) can provide more authentic parcel-level maps to aid urban planning. However, two aspects of VCA still need improvement for more detailed modeling of urban landscape dynamics. One is the lack of simulation of urban renewal prevalent in megacities. The other is the lack of simulation of vertical urban landscape dynamics at the parcel level. Hence, this study should be the first to propose a comprehensive VCA framework for modeling horizontal and vertical multi-type urban landscape dynamics (HV-MVCA) at the parcel level. The HV-MVCA consists of two modules: a deep learning-based horizontal urban landscape dynamic simulation module and a random forest-based (RF) vertical metrics prediction module. Compared with traditional VCA, the HV-MVCA can obtain the highest simulation accuracy with an enhancement of 1.45%-4.56%. The RF-based fitting model can reasonably interpret the vertical metric as the coefficient of determination and the mean absolute percentage error was 0.88 and 28.93%. By localizing shared socioeconomic pathways (SSPs), the horizontal and vertical urban landscape dynamics in the future can be simulated under different scenarios. As the multi-scenario simulation results can provide abundant horizontal and vertical information at the parcel level, the proposed HV-MVCA can help achieve a more comprehensive assessment of many urban-related issues with these indicators, such as energy consumption, climate change, and pollution emissions.

A deep learning semantic segmentation network with attention mechanism for concrete crack detection

In this research, an attention-based feature fusion network (AFFNet), with a backbone residual network (ResNet101) enhanced with two attention mechanism modules, is proposed for automatic pixel-level detection of concrete crack. In particular, the inclusion of attention mechanism modules, for example, the vertical and horizontal compression attention module (VH-CAM) and the efficient channel attention upsample module (ECAUM), is to enable selective concentration on the crack feature. The VH-CAM generates a feature map integrating pixel-level information in vertical and horizontal directions. The ECAUM applied on each decoder layer combines efficient channel attention (ECA) and feature fusion, which can provide rich contextual information as guidance to help low-level features recover crack localization. The proposed model is evaluated on the test dataset and the results reach 84.49% for mean intersection over union (MIoU). Comparison with other state-of-the-art models proves high efficiency and accuracy of the proposed method.

Dynamic responses of a flexible floating modular system subjected to ship impact

An innovative flexible floating anti-collision system (FFAS) has been proposed and developed as restraining structure against ship direct collisions. Consisting of multiple horizontal buoy modules, the collision behaviors of the FFAS were greatly influenced by the intricate interaction between striking ship and the modular system, as well as the complicated coupling of fluid and structure. Hence, the colliding process was always oversimplified by restricting the degree of freedom and dereferencing constant added mass in the past research. To address this problem, experimental tests are conducted in a 3D water basin to build a more realistic simulation of the collision process between the FFAS and head-on navigating ship. The six-DOF motion of the stuck buoy and the tension of the block and mooring lines are synchronously monitored for hundreds of impact cases. The results indicate that the impulse load and ship sliding will occur and the impact duration and the peak tension of the lines are affected significantly. Considering various impact positions, the worst-case scenarios for the block and mooring lines are determined and the safe distance for the FFAS setup is suggested for practical design.

Influence of Forging Parameters on Microstructure and Properties of En AW-6082 Alloy

Aluminum alloys are widely used in automotive industry due to their low density and good corrosion resistance. This category includes alloys based on AlSiMg which are suitable for load bearing parts operating under higher temperatures. This paper deals with analysis of influence of deformation parameters and heat treatment on structure and mechanical properties of EN AW-6082 (AlSi1MgMn) alloy manufactured by horizontal cast module technology. Casted rods were used as a billet, which was formed to defined height by hot open-die forging. Subsequently the precipitation hardening was used as heat treatment. Changes in microstructure were evaluated based on the metallographic analyzes performed by light optical microscopy and scanning electron microscopy using an energy dispersive X-ray spectrometry and electron backscatter diffraction. Mechanical properties were determined by uniaxial tensile test and hardness testing. The results showed, that due to the process parameters, no significant structural changes were observed in the surface layer of forging. However, microstructure is significantly inhomogeneous in the core due to the dynamic softening processes. Mechanical properties are increasing which is significantly influenced by the type and distribution of precipitates emerging during the artificial aging.

Planar Rainbow Refractometry For Size, Refractive Index And Position Measurement Of Droplets In A Plane

Rainbow refractometry can simultaneously measure the temperature and geometric parameters of droplets by analyzing the recorded primary rainbow scattering signal of the droplet. The technique therefore has high potential in measurement applications involving reacting/non-reacting sprays. This study develops the planar rainbow refractometer technique, expanding the measurement dimension from a single "line" measurement to a "planar" measurement. The position of the droplet in the plane is determined by the contour of the rainbow signal, whereas the size and refractive index of the droplet are derived from the extracted rainbow image using the calibrated scattering angle. A simple and compact rainbow optical measurement system is constructed based on horizontal slit modulation, enabling the recording of spatially discrete rainbow signals of droplets in a plane. A novel scattering angle calibration method using a precisely traversed monodisperse droplet stream with a priori parameters is proposed and the algorithm for obtaining the calibration coefficients is evaluated by simulation. Spray verification experiments were carried out. The signal processing consists of image recognition, particle localization, and the rejection of non-spherical droplets. The possibility of estimating droplet number density is also discussed.

Synergetic Horizontal Dipole Orientation Induction for Highly Efficient and Spectral Stable Thermally Activated Delayed Fluorescence White Organic Light‐Emitting Diodes

AbstractRadiative exciton generation and light out‐coupling are two crucial factors for highly efficient organic light‐emitting diodes (OLEDs). Herein, a thermally activated delayed fluorescence (TADF) material DspiroS‐TRZ with high horizontal dipole ratio (HDR, Θ// = 82%) is utilized as the blue emitter as well as the host for an orange‐red TADF emitter TPA‐AQ to fabricate white OLEDs. A synergetic horizontal dipole orientation induction on the transition dipole moment of TPA‐AQ is achieved by the highly orientated DspiroS‐TRZ, resulting in high HDR (Θ// = 96%) of the orange‐red emitter. Owing to the simultaneous efficient triplet exciton utilization and highly orientated binary system, a maximum external quantum efficiency (EQEmax) of 29.3% is achieved for single emission layer (EML) white OLED, with an excellent white light out‐coupling efficiency of 34%. In addition, the carrier recombination in the EML is further regulated by inserting an exciton regulation emission layer, which can relieve the trapping effect of the orange‐red emitter and guarantee stable Langevin recombination and energy transfer processes for improved electroluminescence spectral stability. An EQEmax of 31.2% is ultimately achieved for the double‐EML white OLED, highlighting the key role of horizontal dipole orientation induction and carrier recombination modulation for highly efficient and spectral stable white OLEDs.

Experimental Study of the Fire Dynamics in a Semi-enclosure Formed by Photovoltaic (PV) Installations on Flat Roof Constructions

Flame spread experiments upon a BROOF(t4) compliant flat roof mock-up located below a vertical barrier were carried out for variations in gap height, inclination, subjacent insulation material, and the barrier type (stainless-steel board or photovoltaic (PV) module). A binary flame spread scenario was identified, where re-radiation from the flame facilitated self-sustained flame spread if the gap height to the horizontal panel was below 10 cm for the stainless-steel board and 11 cm for PV modules. These were defined as the critical gap heights. Inclination of the PV modules increased the critical gap height and caused a 25% faster flame spread rate (FSR) than the FSR below horizontal modules with the same gap height at the location of ignition. The faster FSR for inclined modules caused a 40% reduction of the maximum temperature measured at a depth of 70 mm in the insulation materials (242°C). Based on temperatures measured in the insulation materials, the 60 mm polyisocyanurate (PIR) insulation performed slightly better than the 50 mm mineral wool insulation. However, it is expected that the mineral wool would outperform the PIR insulation if tested with the same thickness, as it insulates significantly better at high temperatures. Finally, no sustained flame spread was observed on the back side polymer sheet of the PV modules, but one of the three PV module brands produced burning droplets. Based on the experiments, it can be concluded that the current standards are inadequate as the introduction of a PV system on a compliant roof construction enables flame spread.

Implications of spatial-temporal shading in agrivoltaics under fixed tilt & tracking bifacial photovoltaic panels

The spatial and temporal behavior of the incident sunlight can have important implications for agrivoltaic (AV) crop yield. Here we explore the short term (daily) and long term (monthly) variations of the photosynthetically active radiation (PAR) under various tracking and fixed-tilt agrivoltaic PV modules configurations and propose strategies to minimize the shade-induced crop yield loss. For a fixed row to row PV module spacing, vertically installed PV modules facing East/West provide the best spatial homogeneity and a higher intensity of net daily incident PAR, while the traditional North/South faced fixed tilt PV modules result in a high spatial contrast, i.e., a significantly lower PAR underneath the PV modules as compared to the open space between the adjacent rows of PV modules. The shading behavior for the horizontal single axis tracking PV modules shows a seasonal dependence, a higher shading vertically below the PV modules during winters and vice versa for summers. The spatial variation in the crop yield correlates well with that of the net daily PAR spatial pattern in the case of the shade sensitive crops (e.g., tomato) while the spatial yield for the shade tolerant crops (e.g., lettuce) is less affected by PAR variations. We propose an intercropping approach where the cultivated areas for crops having high and low shade sensitivity are identified based on the calculated spatial PAR pattern. A case study of intercropping lettuce with tomato under various PV module configurations shows that this approach can minimize the biomass loss for shade sensitive crops in the presence of spatial PAR heterogeneity.