bluuebunny/crossref_metadata_2025 huggingface dataset:
Solution approaches for evaporation-driven density instabilities in a slab of saturated porous media
Authors: Kloker Leon H. , Bringedal Carina
Published: September 2022

This work considers the gravitational instability of a saline boundary layer formed by an evaporation-induced flow through a fully saturated porous slab. Evaporation of saline waters can result in the formation of salt lakes as salt accumulates near the top surface. As gravitational instabilities can impede the accumulation of salt, establishing a relation between their occurrence and the value of physical parameters such as evaporation rate is crucial. One step toward determining when gravitational instabilities can arise is to compute the ground-state salinity. In this work, this ground state is analytically derived within the framework of Sturm–Liouville theory. Then, a linear stability analysis in conjunction with the quasi-steady state approach is employed to investigate the occurrence of instabilities. These instabilities can develop and grow over time depending on the Rayleigh number and the dimensionless height of the porous medium. To calculate the critical Rayleigh number, which is used to determine the stability of a particular system, the eigenvalues of the linear perturbation equations have to be computed. Here, a novel fundamental matrix method is proposed to solve this perturbation eigenvalue problem and shown to coincide with an established Chebyshev–Galerkin method in their shared range of applicability. Finally, a two-dimensional direct numerical simulation of the full equation system via the finite volume method is employed to validate the time of onset of convective instabilities predicted by the linear theory. Moreover, the fully nonlinear convection patterns are analyzed.
Influence of superhydrophobic area occupancy and impact angle on the water entry dynamics of spheres
Authors: Tao Tongtong , Wang Zhaochang , Ji Jiawei , Guo Yuhang , Zhu Yongqing , Hu Xidong , Liu Kun , Jiao Yunlong
Published: September 2022

In this work, we reported a kind of deflecting air cavity generation strategy by controlling the superhydrophobic (SHB) area occupancy and the impact angle of water entry. The influence of SHB area occupancy and the impact angle on the water entry dynamics and drag reduction characteristics of spheres are also explored through both experimental and theoretical analysis. For a hemispherically coated sphere, it is found that the formed air cavity would reach a maximum deflecting angle when the impact angle of water entry is 90°. With the increasing impact angle, the deflection displacement of the hemispherically coated sphere in the horizontal direction first increases and then decreases. When the impact angle is 90°, the deflection displacement reaches the maximum. The deflection displacement of the SHB region-modulated sphere in the horizontal direction has the same variation trend. Moreover, the SHB region-modulated sphere exhibits different air cavity morphologies (no cavity, transition state seal, deep seal, and surface seal) at different impact velocities for impact angles of 0° and 180°. The air cavity pinch-off depth and pinch-off time first increase and then stabilize as the SHB area occupancy increases, regardless of whether the impact angle is 0° or 180°, and the value of (Zpinch − Zp)/Zpinch is not affected by the SHB area occupancy (α ∼ 0°). Finally, we demonstrate that SHB region-modulated spheres all move faster than the original spheres, and the sphere with a SHB area occupancy of 0.25 (α ∼ 180°) is able to reduce the drag reduction coefficient to 0.055.
Experimental investigation of the flow features around an elliptical Ahmed body
Authors: Siddiqui Naseeb Ahmed , Agelin-Chaab Martin
Published: September 2022

The standard Ahmed body (SAB) with a rectangular rear end is a simplified, canonical bluff body geometry that shares similarities with generic road vehicles. It is known to produce flow separations and strong vortices at the rear end. The aerodynamic performance of vehicles is significantly affected by such three-dimensional flow structures. This work proposed a modified Ahmed body with an elliptical rear end called the elliptical Ahmed body. The study examines in detail the near-field characteristics of the flow over the elliptical Ahmed body at a slant angle of 25° with a low Reynolds number of 4.31×104 based on the model height. The principal flow features are analyzed using time-resolved and standard particle image velocimetry. The time-averaged and time-resolved analyses revealed a fully detached flow at the rear end that eliminated the slant separation bubble. Furthermore, a significant wake flow restructuring is found to curb the lower recirculation bubble and shift the upper recirculation bubble toward the slant surface. Thus, the elliptical curvature shifts the critical slant angle of 30° in SAB to 25°, which indicates transformation of the high-drag flow structures into low-drag. Several distinct Strouhal numbers are found over the slant surface (St = 0.55–0.88), which are higher than that of the SAB, while no significant change is found in the wake region (St = 0.23–0.50). In addition, the effect on coherent structures is evaluated using proper orthogonal decomposition and dynamic mode decomposition, which shows a considerable difference between the standard and elliptical Ahmed body wake structures. The results of this investigation show that body modification of the Ahmed body using elliptical curvature at the rear end can significantly affect the overall flow features and help improve the aerodynamic performance of the vehicles.
Indentation size effect in steels with different carbon contents and microstructures
Authors: Sarangi Soumya Sourav , Lavakumar Avala , Singh Prince Kumar , Katiyar Prvan Kumar , Ray Ranjit Kumar
Published: September 2022

Indentation Size Effect (ISE) in steels having a wide spectrum of carbon (C) concentrations (wt-%) 0.002 (interstitial-free), 0.07 (microalloyed), 0.19 (low carbon), 0.32 (medium carbon), and 0.7 (high carbon), and microstructures were investigated using Vickers micro-hardness tester. A decrease in micro-hardness with increasing load, i.e. ISE, is observed in all the samples except microalloyed steel. The empirical relations, such as the Nix and Gao model, Minimum Resistance model, and Proportional Specimen Resistance (PSR) model, were used to determine the load-independent or true hardness values. Nix and Gao model was adopted to determine the plastically deformed zone (PDZ) size under the indenter and subsequently correlated with ISE in the materials. It is observed that ISE is absent when the PDZ size becomes comparable to or larger than the grain size of the material.
Crony capitalist deals and investment in South Africa’s platinum belt: a case study of Anglo American Platinum’s scramble for mining rights, 1995–2019
Authors: Nxele Musa
Published: September 2022

This article analyses how crony capitalism emerges as a solution to maintaining investment in platinum mining. Using a case study of platinum, the analytic narrative exploits the quasi-experimental design provided by the nationalisation of mineral rights to evaluate the relationship between mining investment and crony capitalism. Does the policy have the effects intended? This article argues that the answer is no because of the cronyism between mining capital and politically connected black elites. The institutionalisation of cronyism, coupled with low economic growth and shrinking market-based black economic empowerment opportunities, bolstered and legitimised capture of the state. The system of cronyism produced limited investment and limited black productive capital. Poor mining communities and mine workers have suffered from this cronyism, but have recently organised their power to control the operating environment, or the ‘social licence’ to operate.
High-sensitivity temperature sensor based on Mach–Zehnder interferometer filled with dimethyl silicone oil
Authors: Zhu Xiping , Jiang Chao , Guo Xiaoshan , Chen Hailin , Sun Simei , Liu Changning
Published: September 2022

In this paper, a high-sensitivity temperature sensor based on the Mach–Zehnder interferometer (MZI) is designed and verified by experiments. The MZI is a splicing structure of ‘single mode fiber–multimode fiber–quartz capillary–multimode fiber–single mode fiber’. A microchannel was fabricated on the walls of the capillary by femtosecond laser pulses, and dimethyl silicone oil (DSO) was injected into the capillary by the immersion method. When filled with DSO, the microchannel is sealed with epoxy adhesive to form a MZI temperature sensor. When the ambient temperature changes, the DSO in the capillary of the MZI has a very high thermo-optical effect, resulting in a change in the optical path difference in the MZI and a large wavelength shift in the transmission spectrum of the MZI. Therefore, high temperature sensitivity can be obtained by demodulating the wavelength shift of the MZI transmission spectrum. The experimental results show that the temperature sensitivity of the MZI filled with DSO is 7.421 nm °C−1 in the range of 30 °C–50 °C, which is 297 times that of the MZI without DSO (0.025 nm °C−1). In addition, the sensor has a compact structure, robustness, good repeatability and stability.
Electrical devices designed based on inorganic clusters
Authors: Hu Kuo-juei , Yan Weicheng , Zhang Minhao , Song Fengqi
Published: September 2022

The idea of exploring the bottom brink of material science has been carried out for more than two decades. Clusters science is the frontmost study of all nanoscale structures. Being an example of 0-dimensional quantum dot, nanocluster serves as the bridge between atomic and conventionally understood solid-state physics. The forming mechanism of clusters is found to be the mutual effects of electronic and geometric configuration. It is found that electronic shell structure influences the properties and geometric structure of the cluster until its size becomes larger, where electronic effects submerge in geometric structure. The discrete electronic structures depend on the size and conformation of clusters, which can be controlled artificially for potential device applications. Especially, small clusters with a size of 1–2 nm, whose electronic states are possibly discrete enough to overcome thermal fluctuations, are expected to build a single-electron transistor with room temperature operation. However, exciting as the progress may be seen, cluster science still falls within the territory of merely the extension of atomic and molecular science. Its production rate limits the scientific and potential application research of nanoclusters. It is suggested in this review that the mass-produce ability without losing the atomic precision selectivity would be the milestone for nanoclusters to advance to material science.
Classification and utilization of waste electronic components based on triboelectric nanogenerator
Authors: Zhao En , Jiang Kai , Li Bao , Liu Xin , Zeng Fan , Chen Lin , Zhang Hao , Zhu Zhiyuan
Published: September 2022

The rapid development of the internet of things is accompanied by a large number of equipment deployment. When the equipment fails or reaches its service life, tons of e-waste will be generated. Therefore, there is an urgent need to find environmentally friendly and effective ways to recycle and treat e-waste. In this paper, a method of classification detection and resource utilization of waste electronic components based on the triboelectric nanogenerator (TENG) is proposed, which provides a novel idea for electronic waste treatment. We studied the output voltage characteristics of different kinds of TENG based on waste electronic components subject to different environmental loadings. The output characteristics of TENG are explored, reflecting the e-waste categories and processing environment. TENG is also connected with hundreds of light-emitting diodes (LEDs) through rectifier bridge circuit, and the output performance of TENG is characterized by the number and intensity of LEDs.
Absolute parametric decay instabilities of X2 microwave beams in reduced models and fully kinetic codes
Authors: Senstius M G , Gusakov E Z , Yu Popov A , Nielsen S K
Published: September 2022

Nonlinear wave interactions known as parametric decay instabilities (PDIs) have been known to occur in fusion plasmas for many years. In the past, they have generally been considered of little importance in the context of high power microwave beams aimed for X2 heating due to high thresholds. Experimental evidence suggests that non-monotonic density structures, such as islands and ELMs, can lead to low thresholds absolute PDIs. The consequences include degraded electron cyclotron resonance heating performance, absorption into unintended modes and the production of strong scattering, which may damage microwave sensitive equipment. We present a reduced analytical 1D model for absolute PDI of an X-mode microwave beam into a cascade of electrostatic eigenmodes of a non-monotonic density structure. The model is solved numerically and compared with fully kinetic particle-in-cell (PIC) simulations which are computationally much more expensive. The primary decay, which initiates cascade, shows good agreement with the PIC simulations in terms of daughter frequencies, growth rates and saturation, in particular in a weakly nonlinear pump intensity regime. The secondary daughter waves of the reduced model, while visible, do not appear to be the dominant processes in the PIC simulations.
Collective diffusion in a two-dimensional liquid composed of Janus particles
Authors: Huang Tao , Zeng Chunhua , Chen Yong
Published: September 2022

The collective diffusion of anisotropic particles in liquids plays a crucial role in many processes, such as self-assembly. The patchy particle, which is usually nearly spherical in shape, is an important anisotropic particle with different properties from other anisotropic particles like the ellipsoid liquid crystal particles. In the present study, molecular dynamics simulations are performed to study the collective diffusion of a two-dimensional anisotropic liquid system composed of Janus particles. The static structures and diffusion behaviours of anisotropic and isotropic Lennard-Jones liquids are compared. The long-time diffusion behaviour of an anisotropic liquid of nearly spherical Janus particles is found to be similar to that of an isotropic liquid because the orientation of the particles disappears over long-term averaging. The anisotropic properties of the Janus particles are mainly reflected in the spatial correlation of particle orientations and mid-time diffusion behaviour. The difference between nearly spherical anisotropic particles and rod-like particles is also discussed in this paper.
Quantum diagnosis of cancer with heralded single photons
Authors: Lotfipour Hoda , Sobhani Hassan , Khodabandeh Majid
Published: September 2022

The unique properties of single quantum photons have more potential for many applications in quantum metrology. Here, by using state-of-the-art techniques, the precision of the attenuation measurement of light by propagating in the tissue is enhanced and a method to diagnose cancer in the tissue is proposed. The measurement of light with precision beyond the shot-noise limit and near the ultimate quantum limit can be attained using the heralded single photons (HSPs) generated by the spontaneous parametric down-conversion process. The interaction of HSP with normal and malignant breast tissues announces the presence of its partner. Theoretically and experimentally, a quantum approach to diagnosing cancer by comparing the measured attenuation coefficient of the normal and malignant tissues is demonstrated using the HSPs. We experimentally show that it is possible to improve the attenuation uncertainty due to the scattering of HSPs from the bio-sample to distinguish the malignant tissue from the normal tissue. Here, we use a narrow-band filter to remove the Raman scattering effect and consequently increase the attenuation uncertainty. This method is one of the applications of quantum metrology for precision enhancement which can be used in the histology of unstained tissues and tumor margin detection.
Tighter uncertainty relations based on

(α,β,γ)

modified weighted Wigner–Yanase–Dyson skew information of quantum channels
Authors: Xu Cong , Wu Zhaoqi , Fei Shao-Ming
Published: September 2022

We use a novel formation to illustrate the (

α
,
β
,
γ

) modified weighted Wigner–Yanase–Dyson ((

α
,
β
,
γ

) MWWYD) skew information of quantum channels. By using operator norm inequalities, we explore the sum uncertainty relations for arbitrary N quantum channels and for unitary channels. These uncertainty inequalities are shown to be tighter than the existing ones by a detailed example. Our results are also applicable to the MWWYD skew information and the (

α
,
γ

) modified weighted Wigner–Yanase–Dyson ((

α
,
γ

) MWWYD) skew information of quantum channels as special cases.
Two-dimensional tetragonal ZnB: A nodalline semimetal with good transport properties
Authors: Zhao Yong-Chun , Zhu Ming-Xin , Li Sheng-Shi , Li Ping
Published: September 2022

Nodal-line semimetals have become a research hot-spot due to their novel properties and great potential application in spin electronics. It is more challenging to find 2D nodal-line semimetals that can resist the spin–orbit coupling (SOC) effect. Here, we predict that 2D tetragonal ZnB is a nodal-line semimetal with great transport properties. There are two crossing bands centered on the S point at the Fermi surface without SOC, which are mainly composed of the p
xy
orbitals of Zn and B atoms and the p
z
orbitals of the B atom. Therefore, the system presents a nodal line centered on the S point in its Brillouin zone (BZ). And the nodal line is protected by the horizontal mirror symmetry Mz
. We further examine the robustness of a nodal line under biaxial strain by applying up to −4% in-plane compressive strain and 5% tensile strain on the ZnB monolayer, respectively. The transmission along the a direction is significantly stronger than that along the b direction in the conductive channel. The current in the a direction is as high as 26.63 μA at 0.8 V, and that in the b direction reaches 8.68 μA at 0.8 V. It is interesting that the transport characteristics of ZnB show the negative differential resistance (NDR) effect after 0.8 V along the a (b) direction. The results provide an ideal platform for research of fundamental physics of 2D nodal-line fermions and nanoscale spintronics, as well as the design of new quantum devices.
Simultaneous measurements of refractive index and temperature based on a no-core fiber coated with Ag and PDMS films
Authors: Li Yuxin , Chen Hailiang , Zhang Yingyue , Chen Qiang , Wu Biao , Fan Xiaoya , Liu Yingchao , Ma Mingjian
Published: September 2022

A compact surface plasmon resonance (SPR) fiber optic sensor, being utilized to simultaneously measure refractive index (RI) and temperature, is proposed and experimentally demonstrated in this paper. One part of a no-core fiber (NCF) was coated with a silver (Ag) film, and the other part was coated with a silver/polydimethylsiloxane (Ag/PDMS) composite film to stimulate the SPR effect. Due to the two heterogeneous films, two dips appeared in the transmission spectrum and were used to achieve the dual-parameter measurements. The experimental results showed that the RI sensitivity reached 2121.43 nm/RIU and 0 nm/RIU, while the temperature sensitivity reached –0.32 nm/°C and –2.21 nm/°C for the two dips, respectively. Based on the obtained transfer matrix, the measurements of RI and temperature could be demodulated. This designed sensor showed the merits of simple structure, easy to implement, and high sensitivity, demonstrating application prospects in dual-parameter monitoring.
High throughput N-modular redundancy for error correction design of memristive stateful logic
Authors: Zhu Xi , Xu Hui , Yang Weiping , Li Zhiwei , Liu Haijun , Liu Sen , Wang Yinan , Long Hongchang
Published: September 2022

Memristive stateful logic is one of the most promising candidates to implement an in-memory computing system that computes within the storage unit. It can eliminate the costs for the data movement in the traditional von Neumann system. However, the instability in the memristors is inevitable due to the limitation of the current fabrication technology, which incurs a great challenge for the reliability of the memristive stateful logic. In this paper, the implication of device instability on the reliability of the logic event is simulated. The mathematical relationship between logic reliability and redundancy has been deduced. By combining the mathematical relationship with the vector-matrix multiplication in a memristive crossbar array, the logic error correction scheme with high throughput has been proposed. Moreover, a universal design paradigm has been put forward for complex logic. And the circuit schematic and the flow of the scheme have been raised. Finally, a 1-bit full adder (FA) based on the NOR logic and NOT logic is simulated and the mathematical evaluation is performed. It demonstrates the scheme can improve the reliability of the logic significantly. And compared with other four error corrections, the scheme which can be suitable for all kinds of R–R logics and V–R logics has the best universality and throughput. Compared with the other two approaches which also need additional complementary metal–oxide semiconductor (CMOS) circuits, it needs fewer transistors and cycles for the error correction.
A novel hyperchaotic map with sine chaotification and discrete memristor
Authors: Sun Qiankun , He Shaobo , Sun Kehui , Wang Huihai
Published: September 2022

Discrete memristor has become a hotspot since it was proposed recently. However, the design of chaotic maps based on discrete memristor is in its early research stage. In this paper, a memristive seed chaotic map is proposed by combining a quadratic discrete memristor with the sine function. Furthermore, by applying the chaotification method, we obtain a high-dimensional chaotic map. Numerical analysis shows that it can generate hyperchaos. With the increase of cascade times, the generated map has more positive Lyapunov exponents and larger hyperchaotic range. The National Institute of Standards and Technology (NIST) test results show that the chaotic pseudo-random sequence generated by cascading two seed maps has good unpredictability, and it indicates the potential in practical application.
Fatigue analysis of marine diesel engine crankshaft
Authors: Zhu Jialiang , Wang Guixin , Jia Sensen , Gao Wenxiang
Published: September 2022

As one of the critical components of the main engine, the crankshaft must not be damaged during the whole operating life. Hence, fatigue characteristic analysis and life assessment plays an important role in crankshaft development. This paper analyses the fatigue strength of a marine diesel engine crankshaft and the influence of different fillet structures on the safety factor. First of all, in order to get the stress results and the stress load history of crankshaft fillet, this paper uses the finite element method to analyze the whole model and sub-model. Then, the occurrence time and position of the maximum stress in the running process is located by using the programming script. And the load spectrum is obtained by using the rain flow counting method. Finally, through the calculation, the state of maximum stress and fatigue strength are obtained. The minimum safety factor of the crankshaft fillet is 2.209, which is larger than the specified value. Therefore, the diesel engine has high reliability during operation. In order to solve the problem of stress concentration and machining at the fillet, the crankshaft fillets with different structures are also analyzed in this paper. Through the comparative analysis of the proposed scheme, the most suitable crankshaft fillet structure is two-way sinking groove fillet. So the application of this type of fillet should be considered in the design stage of diesel engine crankshaft.
A cross-platform smart drone controller framework – for real-time surveillance and inspection
Authors: Veerappan Chandra Sekar , Kok Keong Peter Loh
Published: September 2022

This can form the basis for strategic management of new Smart Cities that aim to reduce Line-of-Sight piloting overheads and automate surveillance task. In this paper, we propose an architectural design to support the needed capabilities and basic features of a Smart Drone Controller. framework. This prototype framework supports a deployed team of Wi-Fi drones to conduct assigned surveillance. SDC’s machine learning engine evaluated with Deep Learning algorithms to detect target accuracy from drones live video feed. We have used Darknet/YOLO model for custom object detection in Intruder drone and Wall crack detection use cases and accuracy is reaching over 80%, which is encouraging.
Compensation analysis of subsidence angle of supersonic low-altitude cruise target projectile launch
Authors: Guo Hongli , Ren Shaofeng , Yan Huaiqiang , Zhao Hongtao , Wei Chunshuang , Gao Yun
Published: September 2022

Aiming at the launching process of the supersonic barrel-type spinning target projectile, and improving the control accuracy of the open-loop controlled target projectile, making the subsidence angle compensation can improve the accuracy of the launching process, and make the actual flight trajectory closer to the preset theoretical simulation trajectory. Studies have shown that the subsidence angle of the initial launch has a great impact on the actual flight trajectory. To achieve the same control effect, it must be adjusted to the corresponding control strategy. In this article, we provided the subsidence angle analysis method, which can truly reflect the change of the subsidence angle, and realize the precise control of the trajectory through effective compensation.

CCS Concepts: Computing methodologies~Modeling and simulation~Model development and analysis~Model verification and validation
Research on flow field characteristics of nozzle plume for a solid rocket motor
Authors: Jin Helong , Tao Ruyi , Wang Hao
Published: September 2022

In order to explore the flow field characteristics of nozzle plume for a small solid rocket motor (SRM), the two-dimensional axisymmetric N-S governing equations with component transports and chemical reaction terms are established. Then, the finite volume method of AUSM (Advection Upstream Splitting Method) spatial discretization scheme is applied for numerical discretization, and its solution is solved by time iteration to make the plume flow field steady. This technique is applied to research the flow field characteristics and characteristic parameter distributions of nozzle plume under different inflow conditions. The results are shown that: when considering the reburning reactions of nozzle plume, the temperature of the gas jet core area is much higher than the flow field temperature that the reburning phenomenon is not considered. In addition, the reburning phenomenon mainly occurs in the air-gas mixing and gas development areas, but in the initial core area of gas jet, this phenomenon is not obvious. What’s more, with the increase of altitude, the influence area of the gas jet gradually becomes larger. However, as the incoming flow Mach number increases, the intensity of the change of gas temperature along the nozzle axis weakens, and also the number of wave nodes and the influence region of gas jet gradually decrease.
Development technique of xenon composite over-wrap pressure vessel for electric propulsion system
Authors: Ma Tianju , Yu Bin , Zhao Jipeng , Gu Sendong , Yang Wenbo , Ouyang Ruijie , Gu Shanshan
Published: September 2022

The quality, reliability and safety of composite over-wrap pressure vessel (COPV) are strongly depended on manufacture process technology level in terms of discreteness of composite structure and winding process. In fact, the present qualification testing, acceptance testing and non-destructive evaluation techniques only can indirectly proof the quality of COPV, and do not presently adequately verify COPV reliability and safety characteristics. It is necessary to analyse various requirements of COPV manufacture process and corresponding influencing factors. There are 24 COPV development requirements which are specified in the ANSI/AIAA S-081A (S-081A) standard. According to the development requirements, the corresponding structure design, manufacture process and quality test solutions are formulated after comprehensive analysis and discussion. This paper introduced the manufacture process variables that affect the quality, reliability and safety of COPV. The COPV, which will be used to electric propulsion system of space system, were developed successfully by the optimized manufacture process technology. The impact-damage protection plan is illustrated in terms of the whole life cycle of COPV, including fabrication, test, transportation, storage and full stage.
Research on the method of negative acceleration flight test based on simulation
Authors: Jin Rong
Published: September 2022

Negative acceleration flight test is an important part of civil airplane to obtain airworthiness certification. According to civil aviation regulations, engine, APU, fuel, power supply and other systems need to be verified by flight test. In this paper, the factors affecting negative acceleration flight are evaluated by simulation method, such as gross weight (GW), center of gravity (CG), pitch attitude, calibrated airspeed, and stick travel. Relationship between flight path angle (FPA) rate and the calibrated airspeed is formed by approximate calculation. The duration of each negative acceleration flight is suggested to be a minimum of 7 seconds. In order to maximize the time to maintain the negative overload state, a more effective flight test method is proposed.
Design of vehicular flight test simulation platform for a civil airplane
Authors: Jin Rong
Published: September 2022

During the flight test process of newly developed civil airplane, flight tests are often carried out at several typical airports according to different tasks such as high humidity, high temperature and low temperature tests. Using a vehicular flight test simulator to support flight test task not only can address the needs of multi-regional flight test tasks, but also can provide effective support for ensuring flight test safety and improving flight test efficiency. Aiming at the vehicular flight test simulation platform, an extendable vehicle platform is designed to make it has enough inner space to build the flight test simulator. Moreover, according to the uniqueness of the vehicular platform, the visual subsystem and simulation cockpit subsystem are optimal designed. Based on the details above, the overall design of the platform is formed.
An analytical sensitivity theory-based optimization method for composite structures with large-scale variables
Authors: Luo Lilong , Guo Wenjie , Nie Xiaohua
Published: September 2022

This research focusses on large-scale variable optimization techniques for commercial composite wing structures. To achieve a more complete set of results, the layer thickness for composite layers with the same material and ply direction, are set as a design variable in this study. An analytical approach was utilized to deal with the sensitivity analysis so as to study the relationship between displacement, stress and strain constraints. In order to improve the applicability and user-friendliness, the procedure of sensitivity analysis has been programmed within Fortran and integrated into a Computer-Aided Engineering (CAE) software named HAJIF. To compare the consistency and efficiency, the analytical sensitivity calculation method, along with the finite difference method and a semi-analytical method, were employed to optimise a composite aircraft wing structure. The analytical method was found to have the best consistency and efficiency amongst the three optimization methods. With the aid of HAJIF, the wing was optimized with a weight loss ratio of 8.9%. The total optimization time was is 56 times quicker than the finite difference method and semi-analytical method.
Detection of correlated fission fragments with a twin Frisch-grid ionization chamber
Authors: Chen Hongfei , Sun XiaoJun , Zheng Pu , Xiao Jun , Zhu Tonghua , Sun Junjie , Zhu Jianyu , Cao Yu , Yan Jie , Li Zhenghong
Published: September 2022

Twin Frisch-grid ionization chambers (TFGICs) have been
widely used in the measurement of total kinetic energy (TKE),
angular distribution, mass, and charge of the correlated fission
fragments. To study these correlated fission parameters, we have
developed a TFGIC with a digital acquisition system for use at both
the Chinese Mianyang research reactor (CMRR) and neutron science
facility in the Institute of Nuclear Physics and Chemistry (INPC),
as well as the China Spallation Neutron Source (CSNS). The
distribution of the electric field was investigated with Garfield
toolkit, the results showed that the ratio of the electric field of
the collect region to the drift region (Ec
/Ed
) must be
greater than a critical value Z (1.78). An individual experiment,
carried out with a compound alpha source (241Am and
243Am), was used to validate the preliminary performance of
this detector. The effects of the electric field on the anode pulse
height agreed well with the simulation results. Furthermore, the
results also indicated that the energy resolution of (68.40 ±
1.07) keV at 5.39 MeV (243Am) and (69.67 ± 1.09) keV at
5.49 MeV (241Am) could be achieved. An initial in-beam fission
experiment of 235U reaction with 14 MeV neutrons was also
performed to test the setup, and the results showed that the
reconstructed emission angle could achieve a resolution of 0.221
± 0.002 on the difference of the cosines determined from both
halves of TFGIC. The present work primarily reported the development
of a TFGIC with a digital acquisition system in INPC.
Advantages of using larger-diameter pinhole collimator for prompt X-ray imaging during irradiation with carbon ions
Authors: Yamamoto Seiichi , Yabe Takuya , Akagi Takashi , Yamaguchi Mitsutaka , Kawachi Naoki , Kamada Kei , Yoshikawa Akira , Kataoka Jun
Published: September 2022

Prompt secondary electron bremsstrahlung X-ray (prompt
X-ray) imaging using a low-energy X-ray camera is a promising method
for observing a beam shape from outside the subject. However, the
images measured within short times suffer from statistical
noise. Consequently, we performed prompt X-ray imaging with higher
sensitivity using a larger-diameter pinhole collimator and compared
the results with those of a conventional collimator. Prompt X-ray
imaging was conducted during irradiation with pencil beams of
241.5-MeV/n carbon ions to a water phantom. A newly developed X-ray
camera with a 4-mm diameter as well as conventional 1.5-mm-diameter
pinhole collimators was used for the imaging in list mode, and we
compared the prompt X-ray images, energy spectra, and time count
rate curves between 1.5-mm-diameter and 4-mm-diameter pinhole
collimators. The prompt X-ray images taken with the 4-mm-diameter
pinhole collimators had ∼7 times higher sensitivity with 70 %
lower offset fractions originating from the prompt gamma
photons. Furthermore, the ranges were more precisely estimated with
the 4-mm collimator than with the 1.5-mm collimator. The energy
spectra showed less contamination by tungsten-characteristic X-rays
for the 4-mm pinhole collimator. Even for images measured with 0.1-s
intervals, the beam shapes and time count rate curves could be
obtained with less statistical noise using the 4-mm-diameter pinhole
collimators. The use of the 4-mm-diameter pinhole collimator
attached to the X-ray camera had advantages for prompt X-ray imaging
with high sensitivity and low background, enabling us to image the
beams even with short-time measurements.
Converting tropical forests to agriculture increases fire risk by fourfold
Authors: Trancoso Ralph , Syktus Jozef , Salazar Alvaro , Thatcher Marcus , Toombs Nathan , Wong Kenneth Koon-Ho , Meijaard Erik , Sheil Douglas , McAlpine Clive A
Published: September 2022

Deforestation exacerbates climate change through greenhouse gas emissions, but other climatic alterations linked to the local biophysical changes from deforestation remain poorly understood. Here, we assess the impact of tropical deforestation on fire weather risk—defined as the climate conditions conducive to wildfires—using high-resolution convection-permitting climate simulations. We consider two land cover scenarios for the island of Borneo: land cover in 1980 (forest scenario) and land cover in 2050 (deforestation scenario) to force a convection-permitting climate model, using boundary conditions from ERA-Interim reanalysis for the 2002–2016 period. Our findings revealed significant alterations in post-deforestation fire precursors such as increased temperature, wind speed and potential evapotranspiration and decreased humidity, cloud cover and precipitation. As a result, fire weather events that would occur once a year in the forested scenario, are likely to occur four times a year following deforestation. Likewise, for extreme conditions, such as those occurring on longer time-horizons than 20 years, the magnitude of extreme fire weather is likely to double following deforestation. These increases in extreme fire weather conditions demonstrate the key role of tropical forests in regulating regional climate processes, including reduced fire weather risk.
Nineteen vortex equations and integrability
Authors: Gudnason Sven Bjarke
Published: September 2022

The class of five integrable vortex equations discussed recently by Manton is extended so it includes the relativistic BPS Chern–Simons vortices, yielding a total of nineteen vortex equations. Not all the nineteen vortex equations are integrable, but four new integrable equations are discovered and we generalize them to infinitely many sets of four integrable vortex equations, with each set denoted by its integer order n. Their integrability is similar to the known cases, but give rise to different (generalized) Baptista geometries, where the Baptista metric is a conformal rescaling of the background metric by the Higgs field. In particular, the Baptista manifolds have conical singularities. Where the Jackiw–Pi, Taubes, Popov and Ambjørn–Olesen vortices have conical deficits of 2π at each vortex zero in their Baptista manifolds, the higher-order generalizations of these equations are also integrable with larger constant curvatures and a 2πn conical deficit at each vortex zero. We then generalize a superposition law, known for Taubes vortices of how to add vortices to a known solution, to all the integrable vortex equations. We find that although the Taubes and the Popov equations relate to themselves, the Ambjørn–Olesen and Jackiw–Pi vortices are added by using the Baptista metric and the Popov equation. Finally, we find many further relations between vortex equations, e.g. we find that the Chern–Simons vortices can be interpreted as Taubes vortices on the Baptista manifold of their own solution.
Laser-assisted growth of hierarchically architectured 2D MoS2 crystals on metal substrate for potential energy applications
Authors: Fathi-Hafshejani Parvin , Orangi Jafar , Beidaghi Majid , Mahjouri-Samani Masoud
Published: September 2022

Recently, there has been substantial interest in the large-scale synthesis of hierarchically architectured transition metal dichalcogenides and designing electrodes for energy conversion and storage applications such as electrocatalysis, rechargeable batteries, and supercapacitors. Here we report a novel hybrid laser-assisted micro/nanopatterning and sulfurization method for rapid manufacturing of hierarchically architectured molybdenum disulfide (MoS2) layers directly on molybdenum sheets. This laser surface structuring not only provides the ability to design specific micro/nanostructured patterns but also significantly enhances the crystal growth kinetics. Micro and nanoscale characterization methods are employed to study the morphological, structural, and atomistic characteristics of the formed crystals at various laser processing and crystal growth conditions. To compare the performance characteristics of the laser-structured and unstructured samples, Li-ion battery cells are fabricated and their energy storage capacity is measured. The hierarchically architectured MoS2 crystals show higher performance with specific capacities of about 10 mAh cm−2, at a current rate of 0.1 mA cm−2. This rapid laser patterning and growth of 2D materials directly on conductive sheets may enable the future large-scale and roll-to-roll manufacturing of energy and sensing devices.
Implementation and safety evaluation of autoverification for select low-risk, high-volume medications in the emergency department
Authors: Bienvenida Ana , Kroll Christian , Ruhland Dan , Steffenhagen Aaron , Patterson Brian W , Halfpap Joseph
Published: September 2022

Purpose

Use of autoverification has decreased in many emergency departments (EDs) with the expansion of emergency medicine (EM) pharmacists. Few studies have evaluated ways to prioritize verification of medications. Here we describe a process to design, implement, and measure the safety of autoverification of low-risk, high-volume medications.

A 3-month retrospective review of medications ordered and administered in the ED generated a list of medications to be considered for autoverification. Concurrently, a novel risk stratification tool was created to identify low-risk medications. Taking these together, medications that were high volume and low risk were considered potentially autoverified medications (PAMs). To evaluate the safety of PAMs, a retrospective review of the ED medication orders placed before implementation of autoverification was performed. A total of 7,433 medication orders were reviewed. Of these, 3,057 orders (41%) were identified as PAMs. EM pharmacists verified 2,982 (97.5%) of the orders without changes. Of the remaining 93 orders that were modified or discontinued and met autoverification criteria, only 2 (0.07%) were identified as potentially inappropriate for autoverification.

Conclusion

Low-risk, high-volume medications can be safely autoverified in the ED by using a systematic approach to order selection. Using these methods can provide large decreases in verification volume, close to 41%, without compromising patient safety.
Brief Report: An Evaluation of Item Bias on the Functional Activities Questionnaire
Authors: González David Andrés , Clark Michael J , Gonzales Mitzi M , Benge Jared
Published: September 2022

Objective

To evaluate whether the Functional Activities Questionnaire (FAQ), a commonly used measure of functional status in neurodegenerative disease research, performs equivalently across demographically diverse subgroups of participants.

Method

The FAQs from 30,613 National Alzheimer’s Coordinating Center participants were evaluated with a hybrid graded response model-logistic ordinal regression approach to determine the presence of differential item functioning (DIF) within five demographic groups: education, ethnicity, race, language, and sex.

Results

Measurable DIF was observed for FAQ items in all groups; however, measures of effect size, latent trait distributions, and item characteristic curves suggested that the impact was minimal for research and practice.

Conclusions

The FAQ is able to provide minimally biased assessments of daily functioning across diverse participants, suggesting potential value for offsetting disparities in diagnosis and treatment.
CCPLS reveals cell-type-specific spatial dependence of transcriptomes in single cells
Authors: Tsuchiya Takaho , Hori Hiroki , Ozaki Haruka
Published: September 2022

Motivation

Cell–cell communications regulate internal cellular states, e.g. gene expression and cell functions, and play pivotal roles in normal development and disease states. Furthermore, single-cell RNA sequencing methods have revealed cell-to-cell expression variability of highly variable genes (HVGs), which is also crucial. Nevertheless, the regulation of cell-to-cell expression variability of HVGs via cell–cell communications is still largely unexplored. The recent advent of spatial transcriptome methods has linked gene expression profiles to the spatial context of single cells, which has provided opportunities to reveal those regulations. The existing computational methods extract genes with expression levels influenced by neighboring cell types. However, limitations remain in the quantitativeness and interpretability: they neither focus on HVGs nor consider the effects of multiple neighboring cell types.

Results

Here, we propose CCPLS (Cell–Cell communications analysis by Partial Least Square regression modeling), which is a statistical framework for identifying cell–cell communications as the effects of multiple neighboring cell types on cell-to-cell expression variability of HVGs, based on the spatial transcriptome data. For each cell type, CCPLS performs PLS regression modeling and reports coefficients as the quantitative index of the cell–cell communications. Evaluation using simulated data showed our method accurately estimated the effects of multiple neighboring cell types on HVGs. Furthermore, applications to the two real datasets demonstrate that CCPLS can extract biologically interpretable insights from the inferred cell–cell communications.

Availability and implementation

The R package is available at https://github.com/bioinfo-tsukuba/CCPLS. The data are available at https://github.com/bioinfo-tsukuba/CCPLS_paper.

Supplementary information

Supplementary data are available at Bioinformatics online.
A scalable and unbiased discordance metric with H+
Authors: Dyjack Nathan , Baker Daniel N , Braverman Vladimir , Langmead Ben , Hicks Stephanie C
Published: September 2022

A standard unsupervised analysis is to cluster observations into discrete groups using a dissimilarity measure, such as Euclidean distance. If there does not exist a ground-truth label for each observation necessary for external validity metrics, then internal validity metrics, such as the tightness or separation of the clusters, are often used. However, the interpretation of these internal metrics can be problematic when using different dissimilarity measures as they have different magnitudes and ranges of values that they span. To address this problem, previous work introduced the “scale-agnostic” $G_{+}$ discordance metric; however, this internal metric is slow to calculate for large data. Furthermore, in the setting of unsupervised clustering with $k$ groups, we show that $G_{+}$ varies as a function of the proportion of observations assigned to each of the groups (or clusters), referred to as the group balance, which is an undesirable property. To address this problem, we propose a modification of $G_{+}$, referred to as $H_{+}$, and demonstrate that $H_{+}$ does not vary as a function of group balance using a simulation study and with public single-cell RNA-sequencing data. Finally, we provide scalable approaches to estimate $H_{+}$, which are available in the $\mathtt{fasthplus}$ R package.