Angle Dependence Research Articles

Optimal Design of Tilted Building Envelope Considering Air Conditioning Energy Demand, Daylight Utilization and Glare Protection—Case Study

An important energy-saving method to optimize building envelope design is the integration of local climate characteristics. This study attempts to find sloped facade configurations to balance air conditioning energy demand and daylight utilization for four directions in an area with a hot climate. Tilt angle dependence of the air conditioning energy demand, useful daylight illuminance (UDI) and daylight glare index (DGI) are selected to investigate the acceptance thresholds of the tilt angle. The final facade’s configuration is achieved by employing the graphical optimization method. An acceptable solution that balances better daylight performance and less energy consumption by air conditioning is developed. Due to the considered city being located in a low-latitude area with great daylight availability as well as a fully dimmable light control strategy, unbearable glare reduction can be achieved by benefiting from the sloped facades, without necessarily sacrificing much usable daylight. Meanwhile, there is no obvious increase in the demand for lighting energy consumption, and a good outward view is preserved. The sloped rather than vertical facade provides natural solar shading to the east-, south- and west-oriented windows while allowing low-angle winter solar heat to warm the building space. Tilt angles between 35°and 40° are preferred for the east facade, and smaller tilt angles of between 30°and 35° are recommended for the south facade. Larger tilt angles of between 40°and 45° are preferred for the west facade. However, the north-facing facade’s outward tilt would cause an undesirable increase in air conditioning energy demand. The annual air conditioning energy demand of the east-, south- and west-facing space is found to separately decrease by 7.1%, 7.3% and 9.9%, respectively, benefiting from the sloped facades.

Effects of the Growth Facet Shape of Self‐Catalyzed GaAs Nanowires on the Zinc‐Blende–Wurtzite Switching

Herein, the crystal phase switching between the cubic zinc‐blende and hexagonal wurtzite phases in self‐catalyzed GaAs nanowires (NWs) is theoretically studied, considering the dependence of the droplet contact angle on the position at the triple‐phase line. This dependence is calculated for the droplets resting on the NW top facet, which has the shape of truncated hexagon. The nucleation of c and h islands, corresponding to the cubic and hexagonal crystal phases, at the triple‐phase line and in the center of the catalyst–NW interface, is considered within the classical nucleation theory. As a result, the probability of h‐island nucleation as a function of the average contact angle is obtained. It is found that the maximum of this probability shifts to the region of large contact angles when the length of narrow edges of the NW top facet decreases. Also, it is shown that the GaAs island nucleation at the triple‐phase line occurs preferentially in the vicinity of the top facet corners.

REORIENTATION OF THE EARTH REMOTE SENSING SPACECRAFT USING ROTORS

The article describes a method of reorienting of the Earth remote sensing gyrostat satellite using a flywheel engine, while located in the same vertical plane with the observation object. In the course of the study, a geometric dependence of the nutation angle on time was derived, differential equations of the motion of the spacecraft relative to the center of mass were generated and solutions were obtained. These obtained equations allows to determine motion parameters (coordinates and speeds) depending on the inertial mass characteristics of the system, initial conditions and time, as well as control the effect of these parameters on the system. The article presents the results of conducted studies that show the performance of the developed mathematical model. Thanks to the developed model, it is possible to determine the necessary control actions to target the gyrostat satellite to the observation object with high accuracy.

Effect of incidence angle on PV soiling loss

The effect of light incidence angle is crucial for accurate interpretation of soiling sensor readings and soiling loss data. In this study, the effect of incidence angle on soiling loss is investigated under a solar simulator using artificially and naturally produced soiling samples on different types of glass substrates. It was found that the incidence angle dependence of soiling loss can be described satisfactorily using a two-parameter model, which has one power-law parameter associated with dust morphology and a fraction parameter dependent on the substrate’s angular transmittance. These results are applicable to beam radiation; further research is needed to apply them to field conditions in which diffuse solar radiation is significant. Findings from this study may provide an approach for more accurately calculating PV soiling loss based on optical sensor readings and for more meaningful soiling loss comparison across different locations.

High-field immiscibility of electrons belonging to adjacent twinned bismuth crystals

Bulk bismuth has a complex Landau spectrum. The small effective masses and the large g-factors are anisotropic. The chemical potential drifts at high magnetic fields. Moreover, twin boundaries further complexify the interpretation of the data by producing extra anomalies in the extreme quantum limit. Here, we present a study of angle dependence of magnetoresistance up to 65 T in bismuth complemented with Nernst, ultrasound, and magneto-optic data. All observed anomalies can be explained in a single-particle picture of a sample consisting of two twinned crystals tilted by 108° and with two adjacent crystals keeping their own chemical potentials despite a shift between chemical potentials as large as 68 meV at 65 T. This implies an energy barrier between adjacent twinned crystals reminiscent of a metal- semiconductor Schottky barrier or a p-n junction. We argue that this barrier is built by accumulating charge carriers of opposite signs across a twin boundary.

Mathematical Model of Impact Projectile Flight Dynamics as an Element of its Digital Twin

This paper gives the analysis of the structure and characteristics of the mathematical model of the impact projectile’s flight dynamics. The model is designed for being used as an element of the projectile’s digital twin. The model is based on differential motion equations of a gyro-stabilized solid with an axisymmetric mass distribution. Different types of angle variables were chosen for describing aerodynamics and formulating equations of motion. Non-linear (considering the nutation angle) dependences for aerodynamic coefficients are proposed. They are created by applying proven scientific concepts and research methods in aerodynamics of axisymmetric body and by comparing with known numerical and experimental results obtained in exterior ballistics of gyro-stabilized aviation and artillery projectiles. Special aspects of initial conditions for angles and angular velocity were also studied. Since the impact projectile is considered as an axially symmetric body, its self-rotation angle is not of practical inte rest. Using algebraic manipulations, the differential equation for this angle was eliminated from the set of equations. This has made it possible to significantly reduce stiff of the remaining system of differential equations. The Dormand-Prince method is recommended as a method of numerical integration. The method of the eight-order (with seventh-order uncertainty estimate) allows getting the high accurate solution of the differential equations set under relatively small computing costs. The model allows computing the projectile trajectory under various initial conditions, including the flight with high nutation angles up to 87°—89°. As a result, there is a possibility to determine the nature of the interaction between impact projectiles and typical targets (ricochet, surface effect, after-penetration effect) within a wide range of approach angles to the target’s surface (skin) unattainable during the full-scale tests. The possibility of solving similar problems allows to recommend the designed model as an element of the impact projectile’s digital twin intended for testing its exterior ballistics on the digital (virtual) test range. All testing calculations and final modeling were made by using the "GNU Octave" computational software package.

Recalibration of the lunar chronology due to spatial cratering-rate variability

Cratering chronologies are used to derive the history of planetary bodies and assume an isotropic flux of impactors over the entire surface of the Moon. The impactor population is largely dominated by near-Earth-objects (NEOs) since ∼3.5 billion years ago. However, lunar impact probabilities from the currently known NEO population show an excess of impacts close to the poles compared to the equator as well as a latitudinal dependency of the approach angle of impactors. This is accompanied by a variation of the impact flux and speed with the distance from the apex due to the synchronicity of the lunar orbit around the Earth. Here, we compute the spatial dependency of the cratering rate produced by such variabilities and recalibrate the lunar chronology. We show that it allows to reconcile the crater density measured at mid-latitudes around the Chang'e-5 landing site with the age of the samples collected by this mission. Our updated chronology leads to differences in model ages of up to 30% compared to other chronology systems. The modeled cratering rate variability is then compared with the distribution of lunar craters younger than ∼1 Ma, 1 Ga and 4 Ga. The general trend of the cratering distribution is consistent with the one obtained from dynamical models of NEOs, thus potentially reflecting a nonuniform distribution of orbital parameters of ancient impactor populations, beyond 3.5 Ga ago, i.e., planetary leftovers and cometary bodies. If the nonuniformity of the cratering rate could be tested elsewhere in the Solar System, the recalibrated lunar chronology, corrected from spatial variations of the impact flux and approach conditions of impactors, could be extrapolated on other terrestrial bodies such as Mercury and Mars, at least over the last 3.5 billion years. The modeled cratering rate presented here has strong implications for interpreting results of the Artemis program, aiming to explore the South Pole of our satellite, in particular when it will come to link the radiometric age of the samples collected in this region and the crater density of the sampled units.

A Conformable Holographic Sensing Bandage for Wound Monitoring

AbstractChronic wound monitoring can provide personalized pathophysiological information for wound management and treatment. Continuously monitoring the wound milieu via the holographic pH sensor can reflect the wound healing processes. However, the integration with wearable devices is hindered by its inherently restricted interrogation angle dependency within 5°. Herein, a ball bearing‐based double photopolymerization method is developed to fabricate holographic pH sensors with a broader interrogation angle range of 15°–60° in wound exudates. The fabricated holographic pH sensor is then integrated with the flexible ultrathin polyurethane substrate, which replays a total Bragg peak shift of approximately 150 nm with physiological pH changes from 7.00 to 8.75. The conformable holographic pH sensing bandages demonstrate the ability to quantify the pH value under various bending manipulations, simulating the mounting on the body surface. The reversibility in artificial wound exudate demonstrates the durability and capability of real‐time pH monitoring in the wound milieu with minimal effect on the replay wavelength. The addition of electrolytes, albumin, urea, uric acid, lactate, and glucose does not interfere with the readout over the physiological pH range of wound exudates. The obtained conformable holographic sensing bandage benefits the wound healing process monitoring through colorimetric interrogation at point‐of‐care (POC) settings.

Growth and Temperature Properties of the Phase-Matching Angle of 23% Deuterated ADP Crystal.

Theoretical analysis indicated that partially deuterated ammonium dihydrogen phosphate (DADP) crystal with a deuterium content of 23% could realize spectral noncritical phase-matching (S-NCPM) for type-I frequency doubling of an Nd:glass laser. To explore the temperature dependence of the phase matching (PM) angle of the second harmonic generation (SHG) process and the output SHG bandwidth of DADP crystal at 1.053 μm, we used the point-seed rapid-growth method to grow targeted DADP crystal with 23% deuterium content. Experimental results indicated that the grown DADP crystal had high quality and large dimensions (7 × 6 × 6 cm3). Using a femtosecond OPO laser as a tunable light source, the temperature dependence of the PM angle of the SHG process in DADP crystal at 1.053 μm was investigated. The PM angle changed linearly with temperature, as predicted by the theoretical calculation. In addition, under the condition of higher temperature, broad bandwidths of the second harmonic of DADP crystal were still observed. These results provide excellent guidance and reference value for the application of wavelength insensitive phase-matched second harmonic generation in partially deuterated DADP.

Commissioning and clinical evaluation of a novel high-resolution quality assurance digital detector array for SRS and SBRT.

We aimed to perform the commissioning and clinical evaluation of myQA SRS detector array for patient-specific quality assurance (PSQA) of stereotactic radiosurgery (SRS)/ stereotactic body radiotherapy (SBRT) plans. To perform the commissioning of myQA SRS, its dose linearity, dose-rate dependence, angular dependence, and field-size dependence were investigated. Ten SBRT plans were selected for clinical evaluation: 1) Common clinical deviations based on the original SBRT plan (Plan0), including multileaf collimator (MLC) positioning deviation and treatment positioning deviation were introduced. 2) Compared the performance of the myQA SRS and a high-resolution EPID dosimetry system in PSQA measurement for the SBRT plans. Evaluation parameters include gamma passing rate (GPR) and distance-to-agreement (DTA) pass rate (DPR). The dose linearity, angle dependence, and field-size dependence of myQA SRS system exhibit excellent performance. The myQA SRS is highly sensitive in the detection of MLC deviations. The GPR of (3%/1mm) decreases from 90.4% of the original plan to 72.7%/62.9% with an MLC outward/inward deviation of 3mm. Additionally, when the setup error deviates by 1mm in the X, Y, and Z directions with the GPR of (3%/1mm) decreasing by an average of -20.9%, -25.7%, and -24.7%, respectively, and DPR (1mm) decreasing by an average of -33.7%, -32.9%, and -29.8%. Additionally, the myQA SRS has a slightly higher GPR than EPID for PSQA, However, the difference is not statistically significant with the GPR of (3%/1mm) of (average 90.4%% vs. 90.1%, p=0.414). Dosimetry characteristics of the myQA SRS device meets the accuracy and sensitivity requirement of PSQA for SRS/SBRT treatment. The dose rate dependence should be adequately calibrated before its application and a more stringent GPR (3%/1mm) evaluation criterion is suggested when it is used for SRS/SBRT QA.

Optimization of the current spray angle of the nozzles of the adaptive distribution system of a single-support boom sprayer

One of the unsolved problems of plant protection mechanization is the uneven distribution of pesticides due to vertical vibrations of the sprayer boom. At the same time, the variation of the treatment band with each sprayer can reach 38% or more. This issue is even more relevant for single-support wheelbarrow sprayers, which are used in breeding and primary seed production. This significantly affects the quality of the technological operation. A technical solution to this problem could be the use of sprayers with variable spray geometry. Such a solution requires an analytical substantiation of the dependence of the spray pattern angle on the position angle of the sprayer boom. The purpose of the proposed research is to develop a technique for optimizing the spray angle of sprayer nozzles, taking into account the vertical vibrations of the distribution rod. Geometric and mathematical modeling, theoretical analysis of qualitative and agrotechnical parameters of spraying, substantiation of the laws of the technological process of spraying based on the known laws of physics and classical mathematics, as well as a method of nomogramming functions of several variables were used as scientific methods. It has been established that the uniformity of the application of protective equipment is determined not only by the position of the rod in the vertical plane, but also by the value of the root spray angle, the height of the installation of the sprayer and its position relative to the center of oscillation of the rod. An analytical expression is derived that relates the current width of the processing strip from one sprayer to the specified factors. The dependence of the optimal spray angle on the angle of inclination of the sprayer boom is also proposed. A nomogram has been developed that takes into account permissible deviations in the uneven distribution of the working fluid during spraying. The optimization technique is new. It is applicable to the development of software for the sprayer control complex, which is equipped with an adaptive pesticide distribution system in changing conditions.

Evaluation of the Latest Motion Correction Techniques in Periodically Rotated Overlapping ParallEL Lines with Enhanced Reconstruction (PROPELLER) Imaging across Different Vendors

To evaluate the robustness of the latest periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) technology from each vendor against head movements and to investigate their characteristics for effective clinical use. Using a phantom simulating the T2-weighted image of the human brain, images were acquired with devices from CANON MEDICAL SYSTEMS (Tochigi, Japan; hereinafter "Canon"), GE HealthCare (Chicago, IL, USA; hereinafter "GE"), Philips (Amsterdam, Netherlands), and Siemens Healthineers (Forchheim, Germany; hereinafter "SIEMENS"). The head motion patterns were divided into rotation angle dependency (single rotation and multiple rotations) and rotation frequency dependency and evaluated using structural similarity (SSIM). For rotation angle dependency, Canon was robust against small rotation angles and fine movements. Despite the rotation angle, GE was robust against movements, with deep learning reconstruction (DLR) improving correction functionality. Philips could be used with compressed sensitivity encoding (CS), and robustness varied with blade width. SIEMENS was robust against large movements. For rotation frequency dependency, results were similar across the 4 vendors. The rotation angle and rotation frequency dependencies of the PROPELLER technology from the 4 vendors were quantitatively evaluated. Understanding the characteristics of PROPELLER allows for the possibility of providing diagnostic-quality images even for patients who move during head MRI exams by appropriately using PROPELLER.

Antenna Arrays of the Glide Slope for Aerodromes in Areas with High Snow Cover Level

The main means of providing instrumental approach of aircraft for landing are beacon landing systems. It forms in space a trajectory (glide path), located, as a rule, at the angle of 3° in relation to the horizontal plane. The dependence of the glide path angle on the height of the snow cover on the underlying surface when using previously known antenna arrays in the glide slope is demonstrated in the paper. A new class of glide slope antenna arrays is proposed in the study. The requirements for the amplitude-phase distribution of currents along the antenna array of the glide slope, at which the glide path angle does not depend on the reflective properties of the underlying surface and the level of snow cover on it, are determined. We propose a procedure for constructing an antenna array with two subarrays, one of which radiates the so-called “Carrier plus sideband” (CSB) signal, and the second emits the “Suppressed carrier sideband only” (SBO) signal. The procedure of constructing an antenna array with two subarrays, one of which radiates the so-called “Carrier plus sideband” (CSB) signal, and the second emits the “Suppressed carrier sideband only” (SBO) signal are provided. In order to ensure the independence of the glide path parameters from the height of the antenna array (glide path angle and slope of the glide path), the combination of five conditions is specified in the article. A special case of the proposed antenna array is an equidistant antenna array, in which the radiating elements of the subarray of the CSB signal and the subarray of the SBO signal are partially combined. We have performed experimental studies with the 4-element equidistant antenna array as a part of a glide slope prototype. We have carried out flight measurements of the glide path angle at the airfield in the foothill with a difficult terrain for about two years: in summer, winter, next summer and next winter. The snow depth at the airport was 35–40 cm in the first winter, and 30–35 cm in the second winter. The experimental results demonstrate that the changes in the glide path angle of the stated period of time does not exceed one angle minute. This value is comparable with the error of the flight experiment. In order to simulate the influence of a higher level of snow cover on the position of the glide path, we have conducted a special experiment. When the snow cover was of 18 cm on the airfield surface, we lowered all four antennas by one meter and measured the glide path zone. The glide path angle remained the same. Flight tests of a prototype landing system with the proposed glide path beacon demonstrated that this landing system provides parameters for the III-rd category. It means that the aircraft approaching for landing and landing are possible at zero visibility.

Rationale of effective technological scheme for granite quarry mining

The paper examines the technological scheme for granite mining with the use of rock chutes in the conditions of the Rybalsky Quarry. The research purpose is to substantiate effective technological schemes for mining the upper granite quarry horizons to reduce mining costs and improve the final product quality. Research is conducted using: the method of scientific analysis, theoretical research and practice of project and production organizations; mining-geometric calculations; variant method for comparing and selecting technological schemes for mineral mining. As a result, the dependence of the transportation cost of 1 ton of mineral on the transportation distance has been determined, due to which it became possible to assess the effectiveness of using rock chutes in the conditions of the Rybalsky Quarry. The dependence of the rock chute inclination angle on the friction coefficient when rolling down the mined mass has been revealed, which substantiates the rational inclination angle of the rock chute for quarry conditions. Practical value of the research results consists in reducing the cost of transporting minerals from the upper quarry horizons by applying a technological scheme with the mined mass movement using rock chutes.

Влияние скорости воздушного потока на тепловое излучение от углеводородного пожара в резервуаре для хранения нефти

Purpose. The article assesses the effect of air flow velocity on the intensity of thermal radiation from a fire in a vertical steel tank with a floating roof of 65 000 m3 capacity (VSTWFR-65000) with crude oil. The indicators of hazardous fire factors - open flame, smoke and temperature at different wind speeds – have been studied. Methods. The method of numerical modeling in the Fire Dynamics Simulator software package, as well as the method of processing the obtained research results have been used in the study. Findings. The dependence of the flame inclination angle at different air flow speeds has been obtained. The simulation results have been shown: smoke distribution at different wind speeds, as well as temperature change at a distance from the fire source depending on the air flow velocity. Research application field. The results of the study can be used in the development of design documentation for measures to ensure fire safety of a tank farm with floating roof tanks, as well as in adjusting fire extinguishing plans. Conclusions. Based on the simulation results it has been found that with an increase in the air flow velocity the intensity of thermal radiation initially increases and then decreases. It has been found that at an air flow velocity of 9 m/s the maximum thermal radiation reaches 23.43 kW/m2 at the nearest point of the adjacent tank in the projection from the central axis of the burning tank. At an air flow velocity of 6.5 m/s the temperature at the top of the adjacent tank reaches 176 °C, and at 9 m/s – 426 °C, which is higher than the autoignition temperature of oil, which is within 222–256 °C, there by creating a threat of fire spread. The study has defined the maximum distances from the burning VSTWFR-65000 for the safe presence of people, amounting to 47.3; 48.9; 50.2; 53.4; 55.7; 56.8; 59.4 m for wind speed of classes 0, 1, 2, 3, 4, 5 and 6 respectively.

Методика розрахунку основних характеристик підшипників ковзання систем і агрегатів автомобілів та аналізу їх трибологічної ефективності

A methodology for calculating the main characteristics of sliding bearings of car systems and units is proposed. The specified methodical approach is important when evaluating indicators of tribological efficiency of couplings of parts, nodes, systems and aggregates and operational reliability of cars as a whole. The bearing activation model makes it possible to formulate measures to increase the tribological efficiency of the couplings of parts and the level of operational reliability of nodes, systems and aggregates, and cars as a whole. In addition, the parameters of the actuation model also respond to friction modes. It is shown that it is possible to increase the tribological efficiency of the sliding bearing by means of design, technological and operational methods. The main formulas that make it possible to develop algorithms for calculating a set of bearing characteristics are presented: contact pressure, stress, strength, sliding resistance, wear, resource. For this purpose, the following values are used: compliance coefficients and relative load, contact angle, contact pressures, contact displacements, and the stress state in the contact zone. The geometric and power parameters of the bearing are involved in the developed methodology and algorithm. Modes of friction and the nature and magnitude of the load on the bearing are also taken into account. An algorithm for calculating auxiliary and main characteristics of a sliding bearing has been developed. The conditions of continuity and equilibrium in contact are clarified. The differential-integral equation of the operation of the bearing is obtained and the dependence of the current contact angle on the friction path and other parameters of the sliding bearing operation model is obtained. It is shown that the tribological efficiency of sliding bearings is established by the method of comparative analysis of tribotechnical characteristics determined by the results of tests on friction machines and a stand.

Electron transfer rate modulation with mid-IR in butadiyne-bridged donor-bridge-acceptor compounds.

Controlling electron transfer (ET) processes in donor-bridge-acceptor (DBA) compounds by mid-IR excitation can enhance our understanding of the ET dynamics and may find practical applications in molecular sensing and molecular-scale electronics. Alkyne moieties are attractive to serve as ET bridges, as they offer the possibility of fast ET and present convenient vibrational modes to perturb the ET dynamics. Yet, these bridges introduce complexity because of the strong torsion angle dependence of the ET rates and transition dipoles among electronic states and a shallow torsion barrier. In this study, we implemented ultrafast 3-pulse laser spectroscopy to investigate how the ET from the dimethyl aniline (D) electron donor to the N-isopropyl-1,8-napthalimide (NAP) electron acceptor can be altered by exciting the CC stretching mode (νCC) of the butadiyne bridge linking the donor and acceptor. The electron transfer was initiated by electronically exciting the acceptor moiety at 400 nm, followed by vibrational excitation of the alkyne, νCC, and detecting the changes in the absorption spectrum in the visible spectral region. The experiments were performed at different delay times t1 and t2, which are the delays between UV-mid-IR and mid-IR-Vis pulses, respectively. Two sets of torsion-angle conformers were identified, one featuring a very fast mean ET time of 0.63 ps (group A) and another featuring a slower mean ET time of 4.3 ps (group B), in the absence of the mid-IR excitation. TD-DFT calculations were performed to determine key torsion angle dependent molecular parameters, including the electronic and vibrational transition dipoles, transition frequencies, and electronic couplings. To describe the 3-pulse data, we developed a kinetic model that includes a locally excited, acceptor-based S2 state, a charge separated S1 state, and their vibrationally excited counterparts, with either excited νCC (denoted as S1Atr, S1Btr, S2Atr, and S2Btr, where tr stands for the excited triplet bond, νCC) or excited daughter modes of the νCC relaxation (S1Ah, S1Bh, S2Ah, and S2Bh, where h stands for vibrationally hot species). The kinetic model was solved analytically, and the species-associated spectra (SAS) were determined numerically using a matrix approach, treating first the experiments with longer t1 delays and then using the already determined SAS for modeling the experiments with shorter t1 delays. Strong vibronic coupling of νCC and of vibrationally hot states makes the analysis complicated. Nevertheless, the SAS were identified and the ET rates of the vibrationally excited species, S2Atr, S2Btr and S2Bh, were determined. The results show that the ET rate for the S2A species is ca. 1.2-fold slower when the νCC mode is excited. The ET rate for species S2B is slower by ca. 1.3-fold if the compound is vibrationally hot and is essentially unchanged when the νCC mode is excited. The SAS determined for the tr and h species resemble the SAS for their respective precursor species in the 2-pulse transient absorption experiments, which validates the procedure used and the results.

Ion molecule reactions in the HBr+ + CH4 system: a combined experimental and theoretical study.

Reactions in the system HBr+ + CH4 have been investigated inside a guided ion-beam apparatus under single-collision conditions. The HBr+ is vibrational and rotational state selected in the electronic X2Π1/2 state created by (2+1)-REMPI. Due to the exitation scheme employed different rotational states of the HBr+ are accessible. Four reaction channels have been observed. The cross section, σ, for the exothermic proton transfer channel (PT) decreases with increasing collision energy, steeper than predicted by the Langevin model. The cross section also decreases with increasing rotational energy in the HBr+, with the effect of the rotational energy being stronger than that of translational energy. The cross section for the endothermic charge transfer (CT) increased with increasing collision energy. The energy dependence is well reproduced by a simple line of center (loc) model. Although the bromine transfer (BT) is exothermic the observed cross section increased with increasing collision energy due to an activation barrier on the potential energy surface (PES). Analysis by a modified loc model suggest the relevance of an angle dependence of σ. The cross section for the endothermic hydrogen atom abstraction (HA) exhibits a maximum at 2 eV Ecm. The measured cross sections are rationalized by means of reaction dynamics simulations which show good agreement with the experimental cross sections. The dynamics simulations are carried out with a machine learning potential that is developed and benchmarked with ab initio molecular dynamics simulation. The absolute cross sections predicted by reaction dynamics simulations are well within the same order of magnitude while reproducing the trends over three different collision energies for all four reaction channels. Furthermore, the simulations demonstrate various reaction mechanisms for these reaction channels, including a very interesting HBr+ orientation selectivity for the BT reaction channel.

Interlayer angle dependence of photoelectric properties of Sb/SnC van der Waals heterojunction and its application

The discovery of novel properties in a twisted bilayer graphene has opened up new avenues of research in physics and materials science, making the twistronics a new research hotspot. In this paper, based on two-dimensional tin-based materials and antimonene monolayers, six types of Sb/SnC two-dimensional van der Waals heterostructures (vdWH) with different interlayer twist angles are constructed, and their optoelectronic properties and applications are studied by First-principles calculations. All modeling and calculations are performed using the density functional theory (DFT) software Quantum-ATK. The results show that the Sb/SnC vdWHs with six different interlayer twist angles have various band gaps, and when the interlayer twist angles are 10.89°, 19.11°, 23.41°, and 30°, the Sb/SnC vdWH exhibit a type-I band edge alignment, while at 8.95° and 13.59°, they present a type-II band structure. Results of the orbital-projected band structures of the Sb/SnC vdWHs reveals that the change in interlayer twist angles alters the atomic stacking in the heterostructures, thereby modifying orbital coupling and further tuning the electronic structure of the heterostructures. Additionally, the calculated absorption spectra indicate that compared with individual Sb and SnC monolayers, the absorption coefficient of the Sb/SnC vdWHs in the visible light region was significantly enhanced, and the optical absorption characteristics of the heterostructures with different interlayer twist angles varied markedly. In terms of applications, as materials for solar cells, the Sb/SnC vdWHs with interlayer twist angles of 8.95° and 13.59° exhibit photovoltaic conversion efficiencies of 17.48% and 18.59%, respectively; as photocatalysts for the complete water splitting, the Sb/SnC vdWH with an interlayer twist angle of 8.95° could catalytically decompose water across a pH range of 0-2, while a twist angle of 13.59° confines its catalytic activity to pH values of 0 and 1. Therefore, Sb/SnC van der Waals heterostructures, with special rotation angles, hold promise for multifunctional applications in solar energy and photocatalysis fields. More importantly, our study demonstrates that in addition to conventional methods such as strain, doping, and defects, tuning the interlayer twist angle provides a new degree of freedom for manipulating the optoelectronic properties of materials.

Tunability Dependence of All-Optical Liquid Crystal Delay Line on Laser Polarization and Incidence Angle

This work experimentally investigates the optical manipulation of trans-cis swaps and resultantly their optical/electromagnetic imprints as a driver for realizing the tunable delay lines in the microwave X band (8-12 GHz) regime utilizing the polarization and incident angle dependencies of azo-admixed liquid crystals (LCs). Measurement results confirm that the tuning efficacy of the azo-LCs-based delay line is highly dependent on the polarization of the laser beam concerning the rubbing and filling directions of LCs. When the laser light beam is polarized parallel to the rubbed direction as well as the LCs filling direction, the achievable differential phase shift is maximized. Full Text: PDF References T. Sakamoto, Optoelectronic Circuits for Control of Lightwaves and Microwaves (London, IntechOpen 2011). CrossRef J.F. Li, "All-optically controlled microwave analog phase shifter with insertion losses balancing", Eng. Lett. 28, 3 (2020). DirectLink J.P.F. Lagerwall, G. Scalia, "A new era for liquid crystal research: Applications of liquid crystals in soft matter nano-, bio- and microtechnology", Curr. Appl. Phys. 12, 6 (2012). CrossRef S. Kim, K. Seiji, "Photochemical On–Off Switching of One-Dimensional Photonic Crystals Consisting of Azo-Functionalized Liquid Crystal Polymer and Polyvinyl Alcohol", Crystals 9, 12 (2019). CrossRef J.F. Li, "Micro-LED Mass Transfer Technologies", ICEPT (Guangzhou, IEEE 2020). CrossRef U. Chodorow, J. Parka, O. Chojnowska, "Liquid Crystal Materials in THz Technologies", Phot. Lett. Poland 4, 3 (2012). CrossRef