bluuebunny/crossref_metadata_2025 huggingface dataset:
AC conductivity and dielectric properties of MnO2 nanostructures prepared at different temperatures
Authors: Alzahrani Hassan A H
Published: August 2024

An aqueous KMnO4 solution and ethylene glycol were used through the simple in situ redox interaction that was carried out under ambient conditions to create manganese dioxide (MnO2) nanostructures. The as-prepared MnO2 nanostructures are amorphous. After heating at different calcination temperatures, the amorphous MnO2 nanostructures converted into crystalline MnO2 nanostructures. Scanning electron microscopy and powder x-ray diffraction were used to characterize the synthesized MnO2 nanostructures. Also, their AC impedance spectroscopic properties were investigated. PXRD analysis measurement reveals that the crystallinity of the sample increased upon heating MnO2 nanostructures from 200 to 500 °C. In addition, notable changes in morphologies have been observed. The AC electrical conductivity and dielectric properties are measured for all MnO2 nanostructures in the 10 Hz to 100 MHz frequency range at environs conditions. The behavior indicates the increase in conductivity of α-MnO2 sample prepared at high temperature with increased frequency dependence.
Micro-displacement measurement of optical interference with two-ring conjugated vortices
Authors: Yu Xiao , Li Hongru , Zhang Zetian , Zhang Ru , Wang Sha
Published: August 2024

In this paper, we propose a two-ring conjugated vortex beam interferometer. The inner ring and outer ring of the vortex beams has different signs and topological charges. When combined, they produce an intricate pattern of interference fringes that resemble a flower petal, featuring both concentric inner and outer rings which rotates with different directions. We use the scale-invariant feature transformation algorithm to find the feature points. Then we use these points to measure the rotation angle of the outer ring relative to the inner ring and calculate the displacement based on it. We realize the measurement of sub-nanometer displacement. The displacement resolution is 0.38° nm−1. It is improved by about 12.55% compared with only the inner ring. The displacement corresponding to the minimum detectable angle of CCD is reduced from 0.080 nm to 0.060 nm. It will be a promising method in precision machining micro-vibration sensing, surface unevenness sensing, and microbial movement sensing and high-precision measurement of micro-displacement.
Significant tunability and absorptivity of plasmonic NiO-Ni nanoshells dispersed in silica in visible and infrared optical spectra
Authors: Pustovalov V K , Astafyeva L G , Fritzsche W
Published: August 2024

A theoretical study of the optical properties of new NiO-Ni nanoshells (NSs) with different radii and shell thicknesses dispersed in silica was carried out in a wide range of ultraviolet, visible and infrared optical spectra from 200 nm to 5000 nm. The established remarkable tunability of absorption (extinction) spectrum and the high absorption properties of NiO-Ni NSs in the presented spectral ranges are very interesting for use in various photothermal and laser high-temperature technologies, including applications in light-to-heat conversion, solar thermal energy, laser nanomedicine and others.
Research on the measurement method of flight load of flap drive mechanism
Authors: Meng Min
Published: August 2024

The crank is a key component for measuring the flight load of the flap drive mechanism. The geometric shape of the flap crank of a certain aircraft is irregular, with characteristics such as axial bending and asymmetric cross-section, making load measurement difficult. This article proposes a crank load measurement method based on the force transmission analysis of the flap control mechanism and the force analysis of the flap drive crank, which is verified through virtual load calibration experiments. The results indicate that this method is correct and effective.
Adaptive differentiator via continuous terminal sliding mode controller for UAV piloting
Authors: Mohammed Zaouche
Published: August 2024

Piloting UAVs in challenging real flight conditions, particularly in the presence of external disturbances, poses a significant hurdle. These disturbances, if not adequately addressed in the controller design phase, can severely impact performance or even lead to instability. Consequently, the control of UAVs in adverse weather conditions has become a prominent area of research. Notably, various approaches, including the utilization of the High Order Sliding Mode technique (HOSM) for autopilot design, have been proposed.

Despite its robustness and simplicity in application, High Order Sliding Mode Control (HOSMC) has been met with skepticism due to the chattering phenomenon induced by its discontinuous control effects. The inherent challenges associated with HOSMC encompass not only chattering but also singularities. To tackle these issues, a proposed solution involves integrating adaptive differentiators with the continuous terminal sliding mode controller technique for UAV piloting. This approach aims to strike a balance between error reduction and robustness to noise, offering enhanced accuracy within a specific frequency range, irrespective of algorithmic gain tuning.

Moreover, this article introduces an innovative approach employing real-time virtual reality environments for UAV piloting, leveraging the readily available Commercial Off-the-Shelf (COTS) Game, Microsoft Flight Simulator (MSFS). This method serves dual purposes: enhancing UAV piloting techniques and serving as a pedagogical tool to reinforce learners’ understanding in the aeronautical domain. By simulating real-world flight scenarios in a controlled virtual environment, this approach not only enhances the practical skills of UAV operators but also provides a safe and cost-effective means of training and experimentation.
Numerical simulation of the effect of geometric parameters on broadband noise of aeroengine fan/compressor
Authors: Yang Ye , Wang Liangfeng , Wu Junqiang , Yang Dangguo
Published: August 2024

For modern advanced turbofan engines, the increasing broadband noise of the fan/compressor has become an urgent problem. Based on the 3D fan sound source model, the numerical simulation of the effect of geometric parameters on broadband noise prediction is studied. As a result, (1) the three parameters change the sound power level by affecting the kernel function or the upwash velocity spectrum, and the influence laws are different. (2) If the kernel function is affected, the shape and size of the sound power level spectrum will change; if the upwash velocity spectrum is affected, only the sound power level is changed and the spectrum shape is basically unchanged. (3) The number of rotors only affects the upwash velocity spectrum; the number of stators and the chord length of stators only affect the kernel function.
Large angle attitude control of cubesat based on multi-objective optimization
Authors: Xu Shuo , Liao Wenhe
Published: August 2024

The rigid body motion of CubeSat is strongly coupled with the elastic vibration of the flexible structure during the large angle attitude maneuver of the CubeSat. The drastic change of attitude will aggravate the jitter of the solar panel, which will then disrupt its stability. To deal with the contradictions between the rapidity and high-precision stability of large angle attitude maneuver of CubeSats and ensure the higher attitude pointing accuracy of the satellite after the attitude maneuver, this paper presents a multi-objective optimization algorithm based on the quintic polynomial path. This optimization algorithm can reduce the angular velocity as much as possible and obtain the optimal solution of maneuvering time. Then, a terminal sliding mode finite-time controller developed from a nonlinear disturbance observer is proposed. The nonlinear disturbance observer can calculate the disturbance, and the terminal sliding mode finite-time controller can perform feedforward compensation to improve the anti-interference ability of the control system, to achieve the desired finite-time attitude tracking control. Finally, a digital simulation platform based on the momentum wheel and magnetic torque is built. Experimental results show that the quintic polynomial path based on the multi-objective optimization algorithm can effectively reduce the angular velocity during attitude maneuver, and achieve the optimal time solution. The finite-time controller can effectively track the optimal path and ensure the rapidity and stability of attitude maneuvers.
Safety distance analysis for high-speed railway platforms using fluid dynamics and mathematical modeling.
Authors: Liu Jiacheng , Jin Yuxuan , Lv Hanmin , Ding Qirui
Published: August 2024

This paper introduces a model based on Bernoulli’s equation, Dubois’s body surface area calculation method, and Newton’s second law to determine safety markings on high-speed railway platforms. The J coefficient is proposed to calculate net force and safety distance coefficient, resulting in positive ratio coefficients of weight to net force, volume to net force, and inverse ratio coefficients of distance to net force. ANSYS FLUENT software is used for computational fluid dynamics simulations to analyze the impact of different factors on safety marking installation. Recommendations are made based on the findings to improve the safety of station platforms.
End-to-end control of quadrotor based on preference learning
Authors: Shen Qiguang , Zhang Shoufeng , Wu Zhaobin
Published: August 2024

The highly coupled, underactuated, and nonlinear characteristics of quadrotors make it difficult to meet the need for efficient and stable control performance in unknown dynamic environments through the method of modeling and designing controllers. Reinforcement learning allows learning on the base of the controlled object model, updating and optimizing the control strategy with data generated from interactions with the environment, providing a new solution to this problem. However, conveying complex objectives to quadrotors is often challenging, involving the design of reward functions that need to provide sufficient information. Imitation learning can teach agents interactively by learning prior knowledge, but it also faces problems such as the difficulty of acquiring prior knowledge. In this work, our goal is to bypass the design of reward functions and improve the generalizability of quadrotors in different tasks. Specifically, we score the trajectories generated by quadrotors, learn the reward model based on preferences between different trajectories, and use it to train the quadrotors. We can demonstrate that using reward models fitted according to trajectory preferences and directly defining reward functions yields consistent results, maintaining satisfactory learning rates and performance in both “velocity_control” and “hovering_control” tasks.
Identification of turbofan engine state-space model based on flight test data
Authors: Liu Yi
Published: August 2024

The experimental data recorded during flight tests contain rich system dynamic information, which makes it possible to use flight test data for system model identification. Engine state-space model identification based on flight test data can establish an accurate mathematical model of the engine, providing essential support for the design of multivariable engine control systems, engine health monitoring, and fault diagnosis. In this paper, based on engine flight test data, the least squares method is used to identify the state-space model of a certain type of large bypass ratio turbofan engine.
Research and analysis on the rotation of high-voltage electric propulsion harnesses under low temperatures and complex trajectories
Authors: Li Zongliang , Zhao Jingchao , Liu Yizhuo , Song Fei , Li Zhong , Yu Haixiang
Published: August 2024

Spacecraft use electric propulsion to complete tasks such as position maintenance and orbit makeovers, requiring vector adjustment mechanisms to minimize the deviation between the thrust vector of the electric thruster and the spacecraft’s centre of mass. The harness provides high-voltage power to the electric thruster and needs to be coiled and rotated on the thrust vector adjustment mechanism. The bending torque of the high-voltage harness is one of the main factors that need to be considered in the design of the driving capacity of the vector adjustment mechanism. This article proposes a reliable rotation evaluation scheme for high-voltage harnesses in low-temperature environments and complex trajectories. The verification of high-voltage harness torsion times under a wide range of temperatures (-110°C~+150°C), two-dimensional rotation angles (A-axis −18°~+18°, B-axis −25°~+59°), and bending torque tests for high-voltage harness under temperature range combinations (-110°C~+150°C) have been completed. The analysis data shows that the bending torque of a high-voltage harness is monotonically related to the rotation angle and temperature and will increase with the increase of rotation angle and the decrease of temperature. The bending torque of a high-voltage harness is within the driving capacity range of the vector adjustment mechanism motor and can meet the requirements of task applications.
Adsorption mechanism of octadecylamine on inner surface of steam generator feed water pipe of pressurized water reactor nuclear power plant
Authors: Canshuai Liu , Di Wu , Guocai Xi , Fuzhi Zhou , Zhaohui Tian
Published: August 2024

In this paper, the Max Flow software is used to simulate the adsorption process of octadecylamine on carbon steel surface. The adsorption model of octadecylamine on metal interface is established and the adsorption structure is calculated layer by layer. Then, the stable adsorption configuration and the adsorption free energy is calculated. The main conclusions are as follows: 1) Physical adsorption of octadecylamine executes on the surface of carbon steel instead of chemical adsorption, and the adsorption layers increases with octadecylamine concentration. 2) Primary adsorption energy of octadecylamine molecule on the carbon steel surface is mainly provided by van der Waals force. 3) Adsorption layer stacking and operation temperature elevation weaken the spontaneous adsorption trend of octadecylamine molecules.
Progress in the study of corrosion characteristics of water-wall tubes of power station boilers by Cl−/SO4
2-
Authors: Yang H , Zhu Z P , Zhou S M , Li T
Published: August 2024

The higher the unit parameters, the more sensitive water-wall tubes are to the impurity ions in the feed water, especially when the feed water contains aggressive ions such as Cl−, SO4
2-, etc., which often cause severe corrosion to equipment. A great deal of research has been carried out to understand the characteristics of power plant boiler water wall tubes corroded by Cl−/SO4
2-, which is essential to keep industrial boilers running and power stations safe.In this paper, the author firstly elaborates on the furnace water treatment condition and the source of Cl−/SO4
2- in power plant furnace water; then, the development of water-wall tubes of the power plant corrosion study in Cl−/SO4
2- solution is summarized and discussed.
Effect of pre-filming potential on the electrochemical characteristics of 2205 duplex stainless steel in NaCl solution
Authors: Wang L. , Liu Zijian , Chen Xu , Li Renjie , Xie Yujun
Published: August 2024

The effects of pre-filming potential on the electrochemical characteristics and structure of the passivation film of 2205 duplex stainless steel (DSS) in 3.5% NaCl solution were investigated by electrochemical technology and XPS methods. The results showed that when the pre-filming potentials were 0.1 and 0.6 V, the formation process of passivation film was first porous and then dense. However, when the potential rose to 0.9 V, the passivation film eventually underwent an additional porous process. The passivation films pre-formed at different potentials were all bilayer structures. The passivation film of 2205DSS was composed of an inner rich-Cr oxide and an outer rich-Fe oxide. When the pre-filming potential was 0.9 V, FeOOH appeared in the iron-rich oxide layer. The semiconductor properties of the passivation film were independent of the pre-filming potential. With the increase in pre-filming potential, the diffusion coefficient and diffusion flux of the cation vacancies increased, and the migration of cationic vacancies in passivation films became easier.
Ciphertext only attack on QR code optical encryption system with spatially incoherent illumination using a neural network
Authors: Rymov D A , Shifrina A V , Cheremkhin P A , Ovchinnikov A S , Krasnov V V , Starikov R S
Published: August 2024

Optical encryption methods attract a lot of attention owing to their high encryption speed and bandwidth. Recently, neural networks (NNs) have been used for cryptanalysis of optical encryption techniques. In this paper, we for the first time to our knowledge applied a NN for ciphertext only attack on an optical encryption system with spatially incoherent illumination. A NN was used to extract encryption keys from ciphertexts, which can be used to decrypt the plaintext QR codes. Additionally, an optically encrypted QR code was successfully decoded after using the key extracted by the trained NN, that has been processed to account for discrepancies between the numerical model and the optical setup. The results show the vulnerability of the existing optical encryption system with incoherent light to attacks of this type, which indicates the need for improved optical encryption security.
Simple precipitation synthesis and solar light-driven photocatalytic degradation of Ag3PO4 floating photocatalysts
Authors: Bui Thi Thu Hien , Nguyen Pham Tran Anh , Vu Thanh Mai , Tran Thi Huong Giang , Tran Thi Kim Chi , Tran Thi Thuong Huyen
Published: August 2024

A highly efficient and stable photocatalyst, Ag3PO4, was prepared using a simple co-precipitation method at room temperature. The precursors used in this process were AgNO3 and K2HPO4. The resulting Ag3PO4 photocatalyst forms irregularly-shaped spheres with diameters ranging from 300 to 1 μm. The shape of the Ag3PO4 photocatalyst slightly changes when different surfactants (PVA, PVP, PEG) are used. The powdered Ag3PO4 photocatalyst exhibits excellent visible light-driven photocatalytic performance. It is capable of decomposing rhodamine B (RhB) as a model pollutant in just 5 min under visible light irradiation. This performance is quite remarkable. Interestingly, Ag3PO4 floating composite sheets have been achieved using polystyrene (PS) and fumed silica Aerosil 200. After three cycles, the decolorization of RhB dyes remains at 87% with the 30% Ag3PO4@PS/Aerosil 200 sheet. This indicates that the Ag3PO4@PS/Aerosil 200 photocatalyst is highly reusable and stable.
Frost-resistance prediction model for stress-damaged lightweight aggregate concrete based on BPNN: a comparative study
Authors: Fu Chun , Zhang Qiushi
Published: August 2024

With the depletion of natural resources and the requirement of higher strength-weight ratio, lightweight aggregate concrete has attracted more and more attention because of its good thermal properties, fire resistance and seismic performance. However, exposure to low temperature environments accelerates deterioration of concrete, thereby, reduce the service life of lightweight aggregate concrete. Even worse, in cold and arid regions, lightweight aggregate concrete often experiences accidental impacts, wind erosion, earthquakes, and other disasters during service, these damage significantly impact its frost-resistance. Therefore, accurately and quantitatively describing and predicting the frost-resistance of lightweight aggregate concrete under specific disaster conditions is crucial. In this study, take the initial damage degree and freeze-thaw cycles as input variables, while the relative dynamic elastic modulus (RDEM) as an out variable, a frost resistance prediction models for stress-damaged lightweight aggregate concrete was established based on back propagation neural network (BPNN). The results show that the predicted values of BPNN model are in good agreement with the experimental values, and the results are also compared with the revised Loland model which is proposed by another author. Results demonstrate that the average relative error between predicted values of BPNN and experimental values is only 1.69%, whereas the one of revised Loland model is 9.13%, which indicating that the proposed BPNN prediction model can achieve a relatively accurate quantitative assessment of frost-resistance throughout the entire post-disaster lifecycle of lightweight aggregate concrete, it also broadened the idea and provided a reference for the frost resistance prediction of stress-damaged lightweight aggregate concrete.
The effect of ion implantation dose on the friction and corrosion performance of titanium-coated magnesium alloy
Authors: DOU Zhongyu , Luo Shupeng , Zhang Dianxi
Published: August 2024

To enhance the performance of titanium plated coating on the surface of magnesium alloy AZ31, this study investigates the influence of N ion implantation dose on the structure, mechanical properties, and friction corrosion behavior of Ti film. The results reveal that N ion implantation leads to the formation of a new physical phase TiN and induces surface softening. However, with an increase in N ion implantation dose, microhardness of the Ti film increases due to the formation of TiN which enhances its hardness. Friction and wear experiments demonstrate that at maximum implantation dose, the coating exhibits minimal friction coefficient; however, an implantation dose of 5 × 1015 ion cm−2 offers superior wear resistance. The electrochemical test results indicate the corrosion current density and self-corrosion potential of Ti coating decrease with the increase of implantation dose due to the formation of nitride and the presence of N element, and corrosion resistance of the modified coating has been significantly enhanced. The research results provide reference for improving the protection performance of Ti coating on magnesium alloy surface.
Preparation and properties of ultra-high performance concrete incorporation multi-mineral admixtures
Authors: Zhao Wenhua , Kong Jiahui , Sun Qi
Published: August 2024

The impact of multi-mineral admixtures on the sturdiness of ultra-high performance concrete (UHPC). In this study on the premise that multi-mineral admixtures can be utilized in UHPC, we optimized the percentage of three admixtures(limestone powder,slag, and pumice powder) that can replace cement using the Box-Behken design response surface method, and prepared UHPC specimens with multi-mineral admixtures. The rationality of the multi-mineral admixtures approach proposed in this study was confirmed by characterizing the mechanical properties and porosity of the prepared specimens. Durability was also investigated through relevant tests. The results showed that the porosity of the prepared UHPC decreased by 49.4%, the mechanical properties improved by 14.7%, the self-shrinkage and drying shrinkage decreased by 9.8% and 6.2%, respectively, and the volume stability improved. Moreover the resistance to sulfate dry-wet cycling, chloride ion permeation, and carbonization improved significantly. This study, thus, demonstrates a new type of multi-mineral admixture for UHPC with excellent mechanical properties and durability.
Numerical simulation study on solidification proceoss of titanium slab ingot by electron beam cold hearth melting
Authors: Cao Wei , Ma Chong , Li Yang , Gao Lei , Chen Guo , Omran Mamdouh
Published: August 2024

Titanium and titanium alloys are key basic support materials in the field of engineering technology and high technology, and are widely used in the fields of natural gas transportation, chemical corrosion, and marine development. Titanium alloy ingots are often prepared with more solidification defects such as surface cracks and cold shuts, resulting in lower utilization of titanium metal and higher cost of titanium products. The root of this is the lack of in-depth knowledge of the ingot melting and casting process, and the failure to control the thermal conditions of the billet in the molding process within a reasonable range. In this study, based on the Lagrange Euler algorithm, combined with ProCAST finite element software to establish a numerical model, revealing the solid–liquid interface morphology, the length of the transition region, and the change rule of thermal stress under the influence of different process parameters in the solidification process of titanium slab ingot. The results show that with the increase in pulling speed, the depth of the solid–liquid phase line and the width of the mushy zone of slab ingot increase, and the length of the transition region grows. With the increase in casting temperature, the depth of the solid–liquid phase line of the slab ingot decreases, and the mushy zone gradually becomes narrower. The casting temperature and pulling speed are positively correlated with the value of the thermal stress equivalent stress in slab ingots, and the probability of cracks in the corners and ingot surface is higher. This study provides effective theoretical guidance for the realization of stable mass production of high-quality titanium slab ingot.
Effect of Cu content on the microstructure and properties of sintered Fe-0.8C-xCu antifriction materials
Authors: Li Jiaxin , Feng Han , Zhang Jianhua , Chen Pengqi , Cheng Jigui
Published: August 2024

Ferrous antifriction materials (FAMs) play a crucial role in powder metallurgy. Previous studies have primarily focused on exploring the antifriction properties of Fe-C-Cu materials with low copper content (0–5 wt%), while there have been fewer studies on high copper content FAMs. In this study, to investigate the effect of Cu content on the microstructure and properties of sintered FAMs, Fe-0.8C-xCu (x = 5–25 wt%) materials were prepared by powder metallurgy method. The density, microstructure, mechanical performance, friction and wear properties of the samples were analyzed. The results demonstrated a significant change in the relative density, hardness, friction and wear properties of sintered Fe-0.8C-xCu samples with increasing Cu content. Particularly, the Fe-0.8C-15Cu samples exhibited outstanding properties, with a relative density of 77.8%, a hardness of 43 HRB, crushing strength of 380 MPa, an average friction coefficient of 0.21, and a wear rate of 1.36 × 10−8 mm3 N·mm−1. The primary wear mechanisms of the Fe-0.8C-xCu specimens include abrasive wear, adhesion wear, chafing fatigue, pitting, and oxidation. This study aims to provide an experimental and theoretical basis for the development of ferrous antifriction materials suitable for heavy-load conditions.
RF coil that minimizes electronic components while enhancing performance for rodent MRI at 7 Tesla
Authors: Vazquez F , Villareal A , Lazovic J , Martin R , Solis-Najera S E , Rodriguez A O
Published: August 2024

This study introduces a novel volume coil design that features two slotted end-plates connected by six rungs, resembling the traditional birdcage coil. The end rings are equipped with six evenly distributed circular slots, inspired by Mansfield’s cavity resonator theory, which suggests that circular slots can generate a baseline resonant frequency. One notable advantage of this proposed coil design is its reduced reliance on electronic components compared to other volume coils, making it more efficient. Additionally, the dimensions of the coil can be theoretically computed in advance, enhancing its practicality. To evaluate the performance and safety of the coil, electromagnetic field and specific absorption rate simulations were simulated using a cylindrical saline phantom and the finite element method. Furthermore, a transceiver coil prototype optimized for 7 Tesla and driven in quadrature was constructed, enabling whole-body imaging of rats. The resonant frequency of the coil prototype obtained through experimental measurements closely matched the theoretical frequency derived from Mansfield’s theory. To validate the coil design, phantom images were acquired to demonstrate its viability and assess its performance. These images also served to validate the magnetic field simulations. The experimental results aligned well with the simulation findings, confirming the reliability of the proposed coil design. Importantly, the prototype coil showcased significant improvements over a similarly-sized birdcage coil, indicating its potential for enhanced performance. The noise figure was lower in the prototype versus the birdcage coil (NF
birdcage − NF
slotcage = 0.7). Phantom image data were also used to compute the image SNR, giving SNRslotcage/SNRbirdcage = 34.36/24.34. By proving the feasibility of the coil design through successful rat whole-body imaging, the study provides evidence supporting its potential as a viable option for high-field MRI applications on rodents.
Comparative evaluation of image quality between virtual grid and grid portable radiographic systems
Authors: Siddique Azmul H , Ge Gary , Zhang Jie
Published: August 2024

Purpose. Virtual Grid (VG) is an image processing technique designed to address scattered radiation from radiographic systems without a physical grid. It aims to eliminate artifacts caused by grid misalignment and enhance radiographic workflow efficiency. We intend to evaluate image quality between Virtual Grid and grid-based radiographic systems across various patient thicknesses. Methods. A Fujifilm Virtual Grid and GE AMX-4 portable radiographic system was used. Image quality was assessed using MTF, NPS, LCR, and CNR. MTF calculations employed an edge-device method with a 0.1 mmCu sheet. For NPS evaluation, uniform images were acquired with multiple 30 × 30 cm solid water blocks (2 cm thick), overlaid in 2 cm increments to simulate patient sizes from 2cm to 40 cm. LCR and CNR were evaluated using a CIRS test plate with 9-hole depths for a hole diameter of 0.375’. The test object was placed on top of the detector then water blocks, while maintaining the same SID, beam quality, and exposure between the units. Visual assessments were conducted by four readers, quantifying perceived hole numbers. The weighted Cohen’s Kappa and Welch’s T-test were utilized for statistical analysis. Results. At 80% MTF, VG exhibited high contrast resolution of 1.1 l p/mm compared to 1.2 l p/mm for the grid system. VG demonstrated lower noise levels across all frequencies for equivalent patient thicknesses. Welch’s T-test indicated no significant differences in LCR (P = 0.31) and CNR (P = 0.34) between the systems. However, qualitative observation demonstrated VG’s better low contrast response for patient sizes ≥10 cm. The average weighted Cohen’s Kappa value was 0.78. Conclusion. This work indicates the Virtual Grid technology can effectively mitigate scattered radiation to improve granularity and low-contrast resolution in an image compared to a grid system. Furthermore, it can potentially reduce patient dose.
Comparison review of image classification techniques for early diagnosis of diabetic retinopathy
Authors: Wangweera Chayarat , Zanini Plinio
Published: August 2024

Diabetic retinopathy (DR) is one of the leading causes of vision loss in adults and is one of the detrimental side effects of the mass prevalence of Diabetes Mellitus (DM). It is crucial to have an efficient screening method for early diagnosis of DR to prevent vision loss. This paper compares and analyzes the various Machine Learning (ML) techniques, from traditional ML to advanced Deep Learning models. We compared and analyzed the efficacy of Convolutional Neural Networks (CNNs), Capsule Networks (CapsNet), K-Nearest Neighbor (KNN), Support Vector Machine (SVM), decision trees, and Random Forests. This paper also considers determining factors in the evaluation, including contrast enhancements, noise reduction, grayscaling, etc We analyze recent research studies and compare methodologies and metrics, including accuracy, precision, sensitivity, and specificity. The findings highlight the advanced performance of Deep Learning (DL) models, with CapsNet achieving a remarkable accuracy of up to 97.98% and a high precision rate, outperforming other traditional ML methods. The Contrast Limited Adaptive Histogram Equalization (CLAHE) preprocessing technique substantially enhanced the model’s efficiency. Each ML method’s computational requirements are also considered. While most advanced deep learning methods performed better according to the metrics, they are more computationally complex, requiring more resources and data input. We also discussed how datasets like MESSIDOR could be more straightforward and contribute to highly evaluated performance and that there is a lack of consistency regarding benchmark datasets across papers in the field. Using the DL models facilitates accurate early detection for DR screening, can potentially reduce vision loss risks, and improves accessibility and cost-efficiency of eye screening. Further research is recommended to extend our findings by building models with public datasets, experimenting with ensembles of DL and traditional ML models, and considering testing high-performing models like CapsNet.
Automatic motion estimation with applications to hiPSC-CMs
Authors: Finsberg Henrik , Charwat Verena , Healy Kevin E , Wall Samuel T
Published: August 2024

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are an effective tool for studying cardiac function and disease, and hold promise for screening drug effects on human tissue. Understanding alterations in motion patterns within these cells is crucial for comprehending how the administration of a drug or the onset of a disease can impact the rhythm of the human heart. However, quantifying motion accurately and efficiently from optical measurements using microscopy is currently time consuming. In this work, we present a unified framework for performing motion analysis on a sequence of microscopically obtained images of tissues consisting of hiPSC-CMs. We provide validation of our developed software using a synthetic test case and show how it can be used to extract displacements and velocities in hiPSC-CM microtissues. Finally, we show how to apply the framework to quantify the effect of an inotropic compound. The described software system is distributed as a python package that is easy to install, well tested and can be integrated into any python workflow.
Bayesian optimization of non-classical optomechanical correlations
Authors: Pitchford Alexander , Rakhubovsky Andrey A , Mukherjee Rick , Moore Darren W , Sauvage Frédéric , Burgarth Daniel , Filip Radim , Mintert Florian
Published: August 2024

Nonclassical correlations provide a resource for many applications in quantum technology as well as providing strong evidence that a system is indeed operating in the quantum regime. Optomechanical systems can be arranged to generate nonclassical correlations (such as quantum entanglement) between the mechanical mode and a mode of travelling light. Here we propose automated optimization of the production of quantum correlations in such a system, beyond what can be achieved through analytical methods, by applying Bayesian optimization to the control parameters. A two-mode optomechanical squeezing experiment is simulated using a detailed theoretical model of the system and the measurable outputs fed to the Bayesian optimization process. This then modifies the controllable parameters in order to maximize the non-classical two-mode squeezing and its detection, independently of the inner workings of the model. We focus on a levitated nano-sphere system, but the techniques described are broadly applicable in optomechanical experiments, and also more widely, especially where no detailed theoretical treatment is available. We find that in the experimentally relevant thermal regimes, the ability to vary and optimize a broad array of control parameters provides access to large values of two-mode squeezing that would otherwise be difficult or intractable to discover via analytical or trial and error methods. In particular we observe that modulation of the driving frequency around the resonant sideband allows for stronger nonclassical correlations. We also observe that our optimization approach finds parameters that allow significant squeezing in the high temperature regime. This extends the range of experimental setups in which non-classical correlations could be generated beyond the region of high quantum cooperativity.
Effect of surface remelting on the characteristics of IN718 components fabricated using laser powder directed energy deposition
Authors: Thanumoorthy Raja S , Jadhav Satyajeet Vijay , Oyyaravelu R , Bontha Srikanth , A S S Balan
Published: August 2024

Laser Powder Directed Energy Deposition (LP-DED) fabricated components exhibit poor surface finish, necessitating additional post-processing steps prior to their practical application. Enhancing the surface quality of additively manufactured IN718 specimens through conventional post-processing methods is particularly challenging, given the material’s poor machinability and the complexity of the fabricated components. The current study is centered on comprehending the impact of Laser Surface Remelting (LSR) on the surface properties of Laser Powder Directed Energy Deposited (LP-DED) IN718 material. To gain insights into how remelting influences surface characteristics, remelting was carried out using various sets of parameters. The remelted zone exhibited a refined grain structure, leading to increased hardness. Moreover, significant reductions in surface roughness and residual stress were observed in the remelted samples. Regression analysis indicated that laser power played a pivotal role, with positive impact on surface finish and depth of influence but a negative impact on residual stress and hardness. Therefore, considering all the comparison metrics, remelting using laser power of 150 W and a scan speed of 1140 mm min−1 were found to yield optimal surface conditions.
Exploring the benefits of integrated energy-water management in reducing economic and environmental tradeoffs
Authors: Singh Samarth , Quinn Julianne , Kern Jordan , Cuppari Rosa , Characklis Greg
Published: August 2024

Integrated water-energy management is crucial for balancing socioeconomic and environmental objectives in multi-reservoir systems. Multipurpose reservoirs support clean energy production, recreation, navigation, and flood protection but also disrupt natural water flows and fish migration. As hydropower’s role evolves with grid decarbonization, managing these tradeoffs becomes increasingly complex. An integrated model combining economic and environmental factors is essential to inform how to adapt hydropower operations effectively to complement decarbonization of the electric grid. However, existing literature lacks such comprehensive models. This study introduces an integrated water-energy optimization model using the Columbia River Basin (CRB) and Mid-Columbia energy market as a case study. The model couples a simulation of operations of 47 CRB reservoirs with a unit commitment/economic dispatch model of the California and West Coast Power system. We employ Direct policy search and a multi-objective evolutionary algorithm to optimize four objectives: maximize economic benefits from energy production, minimize fossil fuel electricity generation, minimize environmental flow violations, and minimize peak flood levels. Our findings reveal that the integrated model discovers superior operational strategies compared to existing rules, with some policies outperforming current operations on all objectives simultaneously. Insights from the optimized policies include strategies for improved coordination of reservoir operations using storage and inflow data, and the strategic timing of water releases to ensure increased hydropower production leads to less fossil fuel dependence and greater revenue. These results highlight the potential of integrated models to enhance the sustainability of hydropower operations amid a transitioning energy landscape.
Interoceptive active inference
Authors: Gerrans Philip
Published: August 2024

Allostatic active inference is the name for the integrated processing that optimizes organismic function. It derives from the idea that, in order to maintain viability, organisms must implement a model that predicts the consequences of regulatory action. Bodily and affective experiences inform the subject of degree and nature of regulatory success and failure. The avatar is modelled as the entity whose experiences change as a result of internally generated action. It is both source and target of regulation. Predictive processing is a neurocomputational implementation of these ideas, providing testable hypotheses about the nature of neurocognitive processes.
Pain and the avatar
Authors: Gerrans Philip
Published: August 2024

In pain asymbolia, patients say that they are aware of pain but that it does not bother them or it feels as ‘if it’ is not their pain.. Pain asymbolia results from the processing of nociceptive signals not modelled as belonging to the self. Lack of affective response to pain in asymbolia is a consequence, not a cause, of inability to represent the nociceptive signal as ‘mine’. This interpretation is consistent with neural correlates not only of pain asymbolia, but also of a variety of pain and self-related conditions. It also reconciles depersonalization accounts of pain asymbolia with the classic sensorimotor-limbic disconnection accounts that explain it as a phenomenon of ‘hypoemotionality’.
Depersonalization disorder
Authors: Gerrans Philip
Published: August 2024

In depersonalization disorder, patients feel detached from experience and report feeling ‘as if’ experience is not happening to them. There is no deficit of cognition or interoception, but there is a characteristic flattening or absence of affective feeling.The nature of the avatar as an anchor of allostatic inference, neurally realized by circuitry centred on the insula, provides an explanation. The posterior insula is a hub of bodily self modelling. The anterior insula is a hub that: (1) integrates bodily signals with higher-level cognitive and emotional processing and (2) in the process becomes a key substrate for self attribution of affective experience. When the anterior insula is unpredictably and intractably hypoactivated, the subject still feels her bodily experience as her own, but the affective dimension of self modelling is absent. She reports the result in the language of depersonalization.
A vessel without a pilot
Authors: Gerrans Philip
Published: August 2024

In Cotard delusion, the subject believes that she has died or no longer exists. One explanation of the delusion proceeds from the fact that depersonalization is often reported as the experience of feeling ‘as if’ the subject no longer exists. In Cotard delusion, this depersonalization experience is coupled with a metacognitive deficit that leads the subject to endorse the experience or take it at face value. An alternative explanation treats depersonalization and Cotard delusion as products of different impairments to the avatar. Unlike depersonalization in which the avatar is largely intact, in Cotard delusion, the avatar degrades and disintegrates. The result is that the narrative ‘I’ remains as a purely verbal construct detached from an underlying sense of self as a unified persisting entity.
The social self
Authors: Gerrans Philip
Published: August 2024

Intuitively and clinically, people with social anxiety disorder (SAD) fear social interaction because they overestimate the adversity of the social world. They retreat from a world that they misrepresent as hostile and intractable. However, SAD is not essentially a problem of misrepresentation of the social world. Rather inconsistent and fragile self modelling leads to misrepresentation of the social world. The SAD subject represents the social world as essential to her well-being because she lacks confidence in her capacity for independent coping. However, simultaneously, she predicts that engaging with others will lead to humiliation and ostracism. A weak and unstable avatar that leads to conflicting social motivation manifests as SAD symptoms and makes it impossible for her to adaptively regulate or reinterpret her distressing experience.
Una nota supra La/Semper est canendum Fa
Authors: Chan Eleanor
Published: August 2024

One thing above others is known widely about the so-called English cadence: that it is not English. Ever since musicologists of the mid-twentieth century named it, the cadence has laboured under the guise of its deceptiveness. However, as argued in this chapter, the cadence has much to tell us about the musical culture of England at the end of the sixteenth and into the seventeenth century, during the height of its popularity. Using the ‘English’ cadence as its lodestar, this chapter examines the dual accusations of archaism and strangeness levelled at false relations by Thomas Morley in his A Plaine and Easie Practicall Introduction. Ultimately, it demonstrates that the ‘English’ cadence shines a light on the movement towards tonality, the twilight period of solmization, and on the turbulent early years of the Church of England, debates over music in liturgy, and this poignant period of history in general.
Introduction
Authors: Zinkin Melissa
Published: August 2024

This introduction provides a definition of the concept of depth and explains why it is valuable. It also begins to make the case that Kant considers reason to be valuable because it is the source of depth. It discusses passages from Kant’s Lectures on Logic, where he uses the analogy of the depths of a body of water to discuss the thoroughness of cognition, and a passage from the Critique of Pure Reason where Kant distinguishes a presumably superficial “plaster cast of a living human being” from a real “living being” with regard to whether or not their cognition is from principles and is rational. The introduction also provides an overview of the chapters.
Reason, Systematicity, Judgment, and Depth in Kant’s Critique of Pure Reason
Authors: Zinkin Melissa
Published: August 2024

This chapter argues that for Kant reason is the faculty for making deep, systematic judgments. It focuses on Kant’s discussion of the principle of systematicity in the Appendix to the Critique of Pure Reason. It argues that whereas the faculty of understanding is the faculty for judging what something is, reason is the faculty for judging why something is what it is and comprehending it. Once we understand reason to be the faculty for systematically reflecting on something in order to judge why it is what it is, we can make sense of Kant’s statement in the Critique of the Power of Judgment that a critique of the pure power of judgment is a part of the critique of pure reason; to have good judgment is to judge according to the principle of systematicity, which is the principle of reason.
What is a civil war?
Authors: Toft Monica Duffy
Published: August 2024

It should come as no surprise that the definition of “civil war” is hard to pin down. Civil war can be defined as “any armed conflict that involves (a) military action internal to the metropole, (b) the active participation of the national government, and (c) effective resistance by both sides.” This distinguishes civil wars from international, or interstate wars, by the fact that the violence occurred within the territory of a sovereign state, and that the government participated as a combatant.
Causes of civil war
Authors: Toft Monica Duffy
Published: August 2024

The reasons why civil wars occur are highly disputed. There are even disagreements over how to classify different types of civil wars. Still, this debate is relatively new in civil war scholarship. A focus on the different types and risk factors of civil war only emerged in the early twenty-first century. Up until then, studies mainly focused on risk factors without considering that there may be more than one “type” of civil war, with a significant amount of scholarship distinguishing between ethnic and non-ethnic wars, or identity versus non-identity wars.