bluuebunny/crossref_metadata_2025 huggingface dataset:
Lewis acid-catalyzed diastereoselective carbofunctionalization of bicyclobutanes employing naphthols
Authors: Guin Avishek , Bhattacharjee Subrata , Harariya Mahesh Singh , Biju Akkattu T.
Published: May 2023

A mild and diastereoselective Bi(OTf)3-catalyzed ring-opening of BCBs employing 2-naphthols leading to the synthesis of trisubstituted cyclobutanes is reported.
A focus on how latent “codons” are unravelled in synthetic copolymers
Authors: Barner-Kowollik Christopher , Tuten Bryan T.
Published: May 2023

We explore and comment on a key development using advanced mass spectrometric methods coupled with advanced algorithmic learning that can assist in analysing complex copolymers.
Impact of polyelectrolyte adsorption on the rheology of concentrated poly(N-isopropylacrylamide) microgel suspensions
Authors: Elancheliyan Rajam , Chauveau Edouard , Truzzolillo Domenico
Published: May 2023

We explore the impact of three water-soluble polyelectrolytes (PEs) on the flow of concentrated suspensions of poly(N-isopropylacrylamide) (PNIPAm) microgels with thermoresponsive anionic charge density.
Binary grey wolf optimizer with a novel population adaptation strategy for feature selection
Authors: Wang Dazhi , Ji Yanjing , Wang Hongfeng , Huang Min
Published: May 2023

Feature selection is a fundamental pre‐processing step in machine learning that aims to reduce the dimensionality of a dataset by selecting the most effective features from the original features. This process is regarded as a combinatorial optimization problem, and the grey wolf optimizer (GWO), a novel meta‐heuristic algorithm, has gained popularity in feature selection due to its fast convergence speed and easy implementation. In this paper, an improved binary GWO algorithm incorporating a novel Population Adaptation strategy called PA‐BGWO is proposed. The PA‐BGWO takes into account the characteristics of the feature selection problem and designs three strategies. The proposed strategy includes an adaptive individual update procedure to enhance the exploitation ability and accelerate convergence speed, a head wolf fine‐tuned mechanism to exert the impact on each independent feature of the objective function, and a filter‐based method ReliefF for calculating feature weights with dynamically adjusted mutation probabilities based on the ranking features to effectively escape from local optima. Experimental comparisons with several state‐of‐the‐art feature selection methods on 15 classification problems demonstrate that the proposed approach can select a small feature subset with higher classification accuracy in most cases.
Optimal coordinated generation scheduling considering day‐ahead PV and wind power forecast uncertainty
Authors: Admasie Samuel , Song Jin‐Sol , Kim Chul‐Hwan
Published: May 2023

Economic operation and reliable supply‐demand balance are problems of paramount importance in power grids with a massive share of intermittent renewable energy sources (RESs) of great interest. This paper sought an optimal coordinated generation scheduling for day‐ahead power system operation considering RESs and energy storage units. Renewable power generation, particularly, wind and photovoltaic are uncontrollable, whereas can be predicted using forecasting models. Within the proposed framework, a hyperparameter‐optimized long short‐term memory (LSTM) regression model is employed to forecast the day‐ahead weather from the historical time‐series weather data. Eventually, an empirical formula is used to estimate the power conversion from the day‐ahead weather forecasts for a selected PV module and wind turbine. The objective of the scheduling framework is to keep a delicate supply‐demand balance at the lowest possible cost of generation while maintaining the prevailing generation and system constraints. A variance measure uncertainty handling‐based grey wolf optimizer (GWO) technique is used to find the optimal day‐ahead generation schedules and dispatches under RESs forecast uncertainty. The proposed generation scheduling framework is examined on the IEEE 6 and 30‐bus systems. In the studied scenarios, the coordinated operation of generators can decrease the total day‐ahead operating cost for the modified IEEE 6‐bus system by 2.57% compared to supplying electricity generation with conventional generators alone. Likewise, the total operating cost from the coordinated operation of all generation portfolios was reduced by 6.93% from the operating cost of generation during base case simulation (supply only from dispatchable thermal units) on the modified IEEE 30‐bus system. Moreover, the case studies show that coordinated generation scheduling can mitigate the RESs power variability problem, provide secure supply‐demand operation, and minimize the operating cost of electricity generation.
A novel merging strategy model considering the remaining distance in the acceleration lane
Authors: Gu Menglu , Su Yanqi , Wang Chang , Fu Rui , Guo Yingshi , Yuan Wei
Published: May 2023

The driver of a merging vehicle must account for both the lane‐changing risk and the remaining distance in the acceleration lane () during a merging decision‐making process. To investigate the impact of on merge decisions, a typical freeway merging section was selected and monitored with a millimetre radar and a high‐resolution digital camera, which were mounted on the guardrail in the gore area. More than 2000 merging vehicles were captured during the data collection process. The effects of the surrounding vehicles on the merging behaviour were analyzed, and a merging strategy model considering that was based on the random forest algorithm was constructed. The results show that the following vehicle in the target lane is the main factor that affects the merging behaviour of the merging vehicle. When the decision time window was set to 0.6 s, the proposed merging decision model could distinguish ‘Merge’ events and ‘Wait’ events with accuracies of 97.2% and 89.4%, respectively. The overall accuracy of the model was 94.9%, which was 3.9% higher than for a corresponding merging decision model that excluded influence. The proposed merging decision model can aid merging processes and give cues for human‐like merge decisions of automated vehicles.
Regulating properties of Cu2ZnSn(S, Se)4 absorber layer via the extra tiny Mg2+
Authors: Cao Mingyang , Ren Junting , Yang Yanchun , Cui Guonan , Zhao Xin , Liu Yanqing , Mi Yajin , Tian Xiao , Zhu Chengjun
Published: May 2023

Extra cation incorporations have been proved to enhance the properties of Cu2ZnSn(S, Se)4 materials, and help to obtain high‐efficiency solar cells. In this work, the authors study the influence of the extra tiny Mg2+ doping on the properties of Cu2ZnSn(S, Se)4 films. Through tuning the amount of Mg into the precursor solution, the crystallization, morphology, light absorption, and electrical properties all have been improved and can reach the optimum at 3% Mg‐doping, which is in favour of high‐performance CZTSSe devices. The authors’ finding also demonstrates Mg element can be regarded as the new candidate for extra cation incorporations.
A second order asymptotic model for diffusion MRI in permeable media
Authors: Kchaou Marwa , Li Jing-Rebecca
Published: May 2023

Starting from a reference partial differential equation model of the complex transverse water proton magnetization in a voxel due to diffusion-encoding magnetic field gradient pulses, one can use periodic homogenization theory to establish macroscopic models. A previous work introduced an asymptotic model that accounted for permeable interfaces in the imaging medium. In this paper we formulate a higher order asymptotic model to treat higher values of permeability. We explicitly solved this new asymptotic model to obtain a system of ordinary differential equations that can model the diffusion MRI signal and we present numerical results showing the improved accuracy of the new model in the regime of higher permeability.
Optimality, duality and saddle point criteria for a robust fractional interval-valued optimization problem with uncertain inequality constraints via convexificators
Authors: Kummari Krishna , Jaichander Rekha R. , Ahmad Izhar
Published: May 2023

This article focuses on optimality conditions for a robust fractional interval-valued optimization problem with uncertain inequality constraints (RNFIVP) based on convexificators. Using the tools of convexity, an example of sufficient optimality conditions is demonstrated. Robust parametric duality for (RNFIVP) is formulated and utilizing the concept of convexity, usual duality results between the primal and dual problems are investigated. Further, the equivalence between the saddle point criteria of a Lagrangian type function and a robust LU-optimal solution for (RNFIVP) with convexity is also examined.
Missed Osteochondral Shear Injury of the Humeral Head Following Anterior Shoulder Dislocation - A Case Report
Authors: Nötzli Manuela , Ameziane Yacine , Scheibel Markus
Published: May 2023

Case Two months after anterior shoulder dislocation and spontaneous reduction, a 41-year-old man presented movement-related shoulder pain and a functional deficit. An initially
missed osteochondral shearing injury of the humeral head with a Bankart lesion was diagnosed. Due to an extensive posteroinferior defect, an open reduction and internal fixation (ORIF) using
bioabsorbable chondral darts was performed. At the 1-year follow-up, magnetic resonance images showed a completely healed osteochondral fragment and the patient presented an unrestricted
shoulder function.

Conclusion Even in missed osteochondral shear injuries, ORIF with bioabsorbable implants can be associated with an excellent functional outcome and sufficient integrity of the
fragment. The absorbable implants are biocompatible, therefore the risk of revision surgery due to implant irritations is minimized.
GABAergic Effects of Etifoxine and Alprazolam Assessed by Double
Pulse TMS
Authors: Riebel Marco , von Pappenheim Benedikt , Kanig Carolina , Nothdurfter Caroline , Wetter Thomas C. , Rupprecht Rainer , Schwarzbach Jens
Published: May 2023

Introduction There is a need for novel anxiolytics with improved side
effect profiles compared to benzodiazepines. A promising candidate with
alternative pharmacodynamics is the translocator protein ligand, etifoxine.

Methods To get further insight into its mechanisms of action and side
effects compared to the benzodiazepine alprazolam, we performed a double-blind,
placebo-controlled, repeated-measures study in 36 healthy male subjects.
Participants were examined for trait anxiety and side effects and underwent
repeated transcranial magnetic stimulation (TMS) assessments, including motor
evoked potentials (MEP), short intracortical inhibition (SICI), intracortical
facilitation (ICF), and cortical silent period (CSP).

Results We observed attenuation of MEPs by alprazolam but not by
etifoxine. SICI was not significantly affected by alprazolam or etifoxine.
However, the response pattern indicated a lowered SICI threshold after the
administration of etifoxine and alprazolam compared to the placebo. ICF and CSP
were influenced by neither medication. Alprazolam led to higher sedation and
subjective impairment of concentration compared to etifoxine. Individual anxiety
trait scores did not affect TMS parameters.

Discussion This study indicated a favorable side effect profile of
etifoxine in healthy volunteers. Moreover, it revealed differential GABA-related
effects on neuromuscular function by means of TMS. The side effects and TMS
profile of etifoxine are compatible with the involvement of neurosteroidogenesis
and a predominant α3 subunit modulation compared to alprazolam.
Potential role of a novel endoscopic retrieval bag for large colorectal resected specimen: a proof-of-concept study
Authors: Tani Yasuhiro , Takeuchi Yoji , Asada Yuya , Okubo Yuki , Kawakami Yushi , Shichijo Satoki , Kanesaka Takashi , Higashino Koji , Uedo Noriya , Michida Tomoki , Ishihara Ryu , Nakajima Kiyokazu
Published: May 2023

Endoscopic submucosal dissection enables en bloc resection of large superficial colorectal neoplasms. However, it is sometimes challenging to retrieve a large resected specimen via the anus without sample fragmentation. A novel “bag-type” retrieval device has been developed to accomplish complete isolation and non-destructive delivery of oversized specimens. This single-center retrospective study was performed to demonstrate the efficacy of this device for large colorectal resected specimens. Among 17 patients, we identified 18 superficial colorectal lesions for which the use of a novel retrieval device (Endo Carry Large Type) was indicated at specimen delivery at a referral cancer institute from March 2021 to July 2022. The median (interquartile range) tumor size was 62.5 (52.0–79.5) mm. Retrieval of 17 (94%) of 18 resected specimens was performed using the Endo Carry Large Type, and 16 (89%) were successfully retrieved without sample fragmentation. The median (interquartile range) retrieval time was 4 (4–8) minutes, and no apparent adverse events were observed. The novel Endo Carry Large Type device can accomplish colorectal specimen retrieval safely and quickly without specimen damage and therefore may contribute to accurate pathological diagnosis.
Integrated Care for Comprehensive Management of Patients with Osteoarthritis: Program Development and Implementation
Authors: Rucinski Kylee , Crecelius Cory R. , Stucky Renée , Stannard James P. , Cook James L.
Published: May 2023

Treatment of symptomatic osteoarthritis (OA) is often complicated by comorbidities, which put patients at potentially higher risks following operative interventions. Management of these comorbidities is usually separate from orthopaedic care, with patients invited to return to their orthopaedic surgeon once surgical risk factors are better controlled. However, this practice can lead to disjointed care, resulting in uncertainty, mistrust, unmanaged pain, and dissatisfaction for patients. Integrated care teams provide an effective option for coordinated comprehensive nonoperative and preoperative management of patients with knee OA and medical comorbidities. The objective of this article is to summarize the process for implementation of an integrated program to manage patients with symptomatic knee OA and the initial outcomes at our institution as an example of the effects of integrated patient management in orthopaedics. At the author's institution, an integrated program was implemented, successfully addressing the unmet need for coordinated care for patients with bone and joint health problems and medical comorbidities. Patients who completed the full program experienced significant improvements in both pain and function. Potential applications for knee surgeons considering implementing integrated care models could include pre- and postoperative management programs, nonoperative management program, and programs seeking to meet key metrics such as improved readmission rates, patient satisfaction, or value-based care. For effective program implementation, careful planning with convenient referral mechanisms, leadership buy-in, and patient-centered communication protocols are required.
Recommendations for metaverse governance based on technical standards
Authors: Yang Lijuan
Published: May 2023

Technical standards in digital technology can now be utilised to gather numerous digital sub-universes into the metaverse. However, how to create and implement guidance for the metaverse based on technical standards remains unexplored. This study investigated the theoretical framework and policy implications for future technical standards-based metaverse governance (TS-MG). The methodology entailed reviewing the available metaverse governance literature to establish both theoretical and case analyses of practices based on the economics of standards and the theory of networks. This study found that TS-MG encompasses the formulation, security, and compatibility of technical standards. TS-MG should enable the first-mover advantage of standards formulation for standard-setting organisations. It also includes phased governance policies that balance the compatibility and security of standards in the initial, growth, and mature stages of the metaverse. This study highlights the necessity of cooperation among governments, standard-setting organisations, and enterprises to (1) accelerate the development of systemised standards and (2) promote the effective supply of metaverse standards.
Finite-size excess-entropy scaling for simple liquids
Authors: Sevilla Mauricio , Banerjee Atreyee , Cortes-Huerto Robinson
Published: May 2023

Explicit and implicit size effects in computer simulations result from considering systems with a fixed number of particles and periodic boundary conditions, respectively. We investigate these effects in the relation D*(L) = A(L) exp(α(L)s2(L)) between reduced self-diffusion coefficient D*(L) and two-body excess entropy s2(L) for prototypical simple-liquid systems of linear size L. To this aim, we introduce and validate a finite-size two-body excess entropy integral equation. Our analytical arguments and simulation results show that s2(L) exhibits a linear scaling with 1/L. Since D*(L) displays a similar behavior, we show that the parameters A(L) and α(L) are also linearly proportional to 1/L. By extrapolating to the thermodynamic limit, we report the coefficients A∞ = 0.048 ± 0.001 and α∞ = 1.000 ± 0.013 that agree well with the universal values available in the literature [M. Dzugutov, Nature 381, 137–139 (1996)]. Finally, we find a power law relation between the scaling coefficients for D*(L) and s2(L), suggesting a constant viscosity-to-entropy ratio.
High-order OAM states unwrapping in multiplexed optical links
Authors: Yang Chunyong , Liu Rui , Ni Wenjun , Wang Shun , Tian Yongsheng , Hou Jin , Chen Shaoping , Shum Perry Ping
Published: May 2023

To accurately unwrap the high-order orbital angular momentum (OAM) for multiplexed vortex beams is a challenge. In this work, over ±160 order OAM topological charges have been unwrapped in multiplexed optical links. Optical imaging based discrepancy identification enables the multiplexed OAM modes separating in physics, and the intelligent pattern recognition further promotes its unwrapping in numerical domain. Particularly, the combination of annular phase grating and auxiliary beams features compound spiral stripes, which paves the way for optical intensity recognition with low-complexity and high-commonality. Moreover, the spiral direction characterizes the symbol of the OAM states, which dramatically broadens the amount of multiplexed links. Here, optical separating means assisted by intelligent pattern recognition opens up a new route to high-speed and large-capacity optical communication, which may shed new light on 6G application.
Analytical harmonic vibrational frequencies with VV10-containing density functionals: Theory, efficient implementation, and benchmark assessments
Authors: Liang Jiashu , Feng Xintian , Liu Xiao , Head-Gordon Martin
Published: May 2023

VV10 is a powerful nonlocal density functional for long-range correlation that is used to include dispersion effects in many modern density functionals, such as the meta-generalized gradient approximation (mGGA), B97M-V, the hybrid GGA, ωB97X-V, and the hybrid mGGA, ωB97M-V. While energies and analytical gradients for VV10 are already widely available, this study reports the first derivation and efficient implementation of the analytical second derivatives of the VV10 energy. The additional compute cost of the VV10 contributions to analytical frequencies is shown to be small in all but the smallest basis sets for recommended grid sizes. This study also reports the assessment of VV10-containing functionals for predicting harmonic frequencies using the analytical second derivative code. The contribution of VV10 to simulating harmonic frequencies is shown to be small for small molecules but important for systems where weak interactions are important, such as water clusters. In the latter cases, B97M-V, ωB97M-V, and ωB97X-V perform very well. The convergence of frequencies with respect to the grid size and atomic orbital basis set size is studied, and recommendations are reported. Finally, scaling factors to allow comparison of scaled harmonic frequencies with experimental fundamental frequencies and to predict zero-point vibrational energy are presented for some recently developed functionals (including r2SCAN, B97M-V, ωB97X-V, M06-SX, and ωB97M-V).
Bovine babesiosis diagnostic toolbox: Diverse targets for meaningful outcomes
Authors: Guillemi Eliana Carolina , Farber Marisa Diana
Published: May 2023

Bovine babesiosis is caused by the intraerythrocytic protozoans
Babesia bovis
and
Babesia bigemina
in tropical and subtropical regions worldwide. The diagnosis of these tick-borne pathogens may represent a challenge due to the low parasitaemias usually found in
Babesia
persistent infections and also in acute cases. Additionally, the correct determination of the epidemiological status of a herd is a key point for further diagnostic interpretations. In this regard, in this work, we review the available diagnostic tools and suggest algorithms facing different epidemiological scenarios. Finally, we highlight the need for new sensitive and accurate point-of-care diagnostic tools for field babesiosis detection. The development of an international shared database for epidemiological data recompilation would be beneficial for the further design of diagnostic tools and vaccines.
Influence of colored cross-correlated noise on stochastic resonance for an underdamped bistable system subjected to multiplicative and additive noises
Authors: Qiu Qian , Jiang Shiqi , Yuan Shihui , Shi Xiaojiang , Li Liang , Wang Zhanxue , Zhang Xueyuan , Qin Dongxing , Guo Feng , Wang Lin , Yan Jiajia , Wang Yuxin , Liu Danni
Published: May 2023

The stochastic resonance (SR) behavior for an underdamped bistable system with colored cross-correlated noise between multiplicative and additive noise is investigated. The stationary probability density is obtained under the condition of the detailed balance. The expressions for the signal-to-noise ratios (SNRs) for two initial states is deduced by applying two-state theory under the adiabatic condition. The analysis result indicates that the SR phenomenon takes place when the SNRs vary with the coupling strength and the correlation time of the cross-correlated noise. Double SR phenomenon occurs on SNRs’ curves with the increase of the strength of the additive noise. One resonance peak exists when the SNRs change with the damping coefficient and with the intensity of the multiplicative noise.
Improvement of energy resolution of x-ray transition-edge sensor using K-means algorithm and Wiener filter
Authors: Ma 马 Qingxiao 卿效 , Zhang 张 Wen 文 , Li 李 Peizhan 佩展 , Wang 王 Zheng 争 , Feng 冯 Zhifa 志发 , Yang 杨 Xinkai 心开 , Zhong 钟 Jiaqiang 家强 , Miao 缪 Wei 巍 , Ren 任 Yuan 远 , Li 李 Jing 婧 , Shi 史 Shengcai 生才
Published: May 2023

We develop an x-ray Ti/Au transition-edge sensor (TES) with an Au absorber deposited on the center of TES and improved its energy resolution using the K-means clustering algorithm in combination with Wiener filter. We firstly extract the main parameters of each recorded pulse trace, which are adopted to classify these traces into several clusters in the K-means clustering algorithm. Then real traces are selected for energy resolution analysis. Following the baseline correction, the Wiener filter is used to improve the signal-to-noise ratio. Although the silicon underneath the TES has not been etched to reduce the thermal conductance, the energy resolution of the developed x-ray TES is improved from 94 eV to 44 eV at 5.9 keV.
A novel thrust vector nozzle with conical surface based on Coanda effect
Authors: Zheng Hai-bo , Huang Jiang-tao , He Cheng-jun , Wu Bin , Gao Chao
Published: May 2023

In this paper, a novel thrust vector control method based on Coanda effect is proposed for conical surface. The effect of thrust vector control is studied by computation fluid dynamic (CFD) numerical simulation. When there is no side plate on both sides of Coanda surface, there are large vortex structures on both sides of nozzle wake, and the vector control cannot be realized. After adding the side plate, the comprehensive control of the pitch and yaw thrust vectors was realized. When the nozzle pressure ratio (NPR) is 2~2.4, the pitch and yaw vector angles decreased with the increase of NPR, and the maximum pitch vector angle is 8°. And the yaw vector angle is 8°.
A review of the design of medium and large open reinforced structures in composite fuselages
Authors: Zhang Yongjie , Zhang Ming
Published: May 2023

Composite materials are widely used in the design and manufacture of modern civil aircraft fuselage structures. Some large airliners already have full-size composite fuselages, which reduced the weight of the fuselage structure, but the problem of reinforcing the opening of the composite fuselage is also very important. In this paper, the design of medium and large scale open reinforcement structures in composite fuselages is focused. The force characteristics of passenger doors, cargo doors, landing gear hatch openings, and the reinforcement structure form are elaborated, and based on the current research status at home and abroad, the future development of composite fuselage opening reinforcement design is prospected.
Analytical and experimental study on honeycomb sandwich plates reinforced by ring beam of satellites
Authors: Zhu Dalei , Wang Xiaoxin , Yao Shuang , Zhang Jianfeng , Jiao Mengmeng
Published: May 2023

The equivalent parameters of hexagon aluminum honeycombs are work out with the theories of sandwich plates in this paper. The honeycomb sandwich plate reinforced by ring beam applied with static load is simulated by the finite element model of honeycomb sandwich plates, which is validated by static test. The research results show that the numerical calculation error of the honeycomb sandwich plate is less than 10% compared with test results, which is acceptable for an engineering project, and the mechanical behavior of the honeycomb sandwich plate can be described in detail. Thus, the method of equivalent honeycomb parameter is proved to be effective for the design and analysis of honeycomb sandwich plates. The influence of equivalent elasticity modulus and equivalent shear modulus to honeycomb sandwich plates can be reflected exactly from the results which are figured out with the equivalent theories of sandwich plates. The assembly clearance and assembly accuracy have a significant influence to the test results of honeycomb sandwich plates, which is obvious especially at a lower load level.
Mixing and combustion characteristics analysis for solid rocket ramjet
Authors: Lei Xiaoyu , Sun Lin , Cheng Jiming , He Desheng , Bao Futing , Feng Xiping
Published: May 2023

It is of great significance to study the mixing combustion characteristics of solid rocket ramjet for better organizing the secondary combustion of the air flowing into the inlet and the combustion-rich gas, enhancing the mixing degree of the supplementary combustion chamber, and improving the combustion efficiency. In this paper, the L-W model is used as the boron particles ignition combustion model. Combined with the UDF function of fluent, the boron particle ignition combustion program is self-programmed, the finite rate/eddy dissipation model is used as the gas combustion model, and the Realizable k-e turbulence model is used as the turbulence model. The numerical simulation was carried out under the cold flow state and the hot flow state, and the flow field distribution and parameters were obtained, and the mixing characteristics were analyzed. The error of simulation results and test results shows that that the numerical simulation results are in good agreement with the experimental results. By comparing the combustion efficiency and mixing degree, it is found that generally, When the mixing effect is not good, the combustion efficiency must be bad; When the mixing effect is good and the mixing degree is high, the combustion efficiency may be high.
Optimization of auxiliary fuel tank layout to decrease the aircraft empty weight
Authors: Wang Rui , Shi Fangyu
Published: May 2023

The modern civil aircraft has the trend to utilize the auxiliary fuel tank to increase the range. This paper presents an optimization concept for fuel tank design to optimize auxiliary fuel tank placement in aircraft to decrease the aircraft empty weight. A model formulation has been created to satisfy the minimum fuel weight requirement and the aircraft center of gravity limit. To solve the fuel tank layout issue, the integer linear programming algorithm has been applied. In order to validate the concept a simulation model and different calculation cases have been built. The calculation results show that the method can effectively reduce the aircraft empty weight and can gain high benefits.
A tracking method for GEO space targets based on adaptive memory attenuation UKF
Authors: Jia Senhao , Sun Shaoyong , Fang Hui , Li Libin , Zhang Hengguang
Published: May 2023

Aiming at the problem that the nonlinearity of the tracking state equation and the problem of strong noise in the measurement process in the process of tracking the target, a non-cooperative target tracking method in geostationary earth orbit based on adaptive memory attenuation UKF is proposed. Firstly, the relative motion model of the non-cooperative target is constructed, and the state equation and measurement equation are established. Use the memory attenuation adjustment factor to enhance the correction effect of the new measurement on the state estimation, improve the adaptability of the filtering method to nonlinearity and noise, and finally the relative motion trajectory of the space non-cooperative target is obtained. Finally, the standard UKF algorithm and improved UKF algorithm are applied to target tracking and compared by simulation. The deviation of the three coordinate axis components of the actual motion trajectory and the predicted trajectory of the space target is used as the evaluation index. The simulation results show that the filtering accuracy of the improved UKF algorithm is significantly improved, while taking into account the real-time performance of on-orbit tracking.
Design and analysis of direct abort trajectory for a crewed lunar mission based on the quasi-lambert problem
Authors: Dong Tianshan , Wang Hailiao , Luo Qinqin , Han Chao
Published: May 2023

A direct design method for direct abort trajectory based on the quasi-lambert problem is proposed. The re-entry constraint is analytically addressed via a quasi-lambert problem instead of variables iteration and optimization method in the past. Then a new parameter is introduced to determine the plane. The exact solution is determined by differential correction based on the initial solution. Numerical simulation is carried out to test the validity and efficiency of the method. The comparison with STK verifies its reliability. Additionally, the characteristics of direct abort trajectory and their application in the option strategy for different abort ways are studied. The flight time and abort point affect the abort trajectories’ velocity increment and the latitude of the landing area.
Design of flow controller for aviation electric fuel pump
Authors: Wenlong Zhang , Xiao Ding , Jianghong Li
Published: May 2023

In order to meet the demand of high-precision flow control and modular design of aviation electric fuel pump control system, the flow controller is analyzed and designed from the demand of aviation engines for electric fuel pump. Tests show that the steady-state control deviation of the controller is no more than 1% for mass flow rate, and the dynamic control deviation of mass flow rate is no more than 3% in the range of 50kg/h~2000kg/h. A flow controller with high integration degree, high control accuracy and excellent dynamic characteristics for new pump-control system was designed for aero engine.
Effect of flow distribution on shock vector nozzle vector performance
Authors: Shu B W , Huang J T , Gao Z H , He C J
Published: May 2023

For the dual-slot jet controlled two-dimensional shock vector nozzle, the effect of flow distribution on the vector performance of the nozzle is studied by RANS method, in which the total flow rate is unchanged. The results show that the flow distribution has no effect on the thrust coefficient. Increasing the downstream jet flow and reducing the upstream jet flow helps to improve the vector angle and vector efficiency, and the effect is obvious when there is separation and re-attachment between the two jets. Increasing the upstream jet flow and reducing the downstream jet flow will reduce the vector angle. The effect is not noticeable when the separation zone between the two jets is stable and no re-attachment. Maintaining a stable separation zone between dual-slot jet without re-attachment helps improve the vector performance of SVC nozzles. The dual-slot jet flow distribution should aim to eliminate reattachment of separation between jets.
Profitability of hybrid power plants in European markets
Authors: Habbou Hajar , Leon Juan Pablo Murcia , Das Kaushik
Published: May 2023

As markets continue to evolve, hybrid power plants (HPPs) are attracting the interest of plant operators and industry players alike. With their ability to provide flexible dispatchability, HPPs are poised to become a competitive solution in future energy markets, particularly in grid ancillary markets (such as frequency control, reactive power control and black-start). Moreover, resource complementarities present in some sites have the potential to significantly improve production predictability of collocated HPPs. To assess the profitability of HPPs in European markets, a hybrid sizing algorithm is applied to three locations across Europe with distinct resource distribution characteristics. The sizing tool implemented includes several novel features that are not typically incorporated into existing sizing software currently available on the market. This includes turbine selection, a simplified physical design of the wind power plant, a surrogate wake model, and a simplified solar panel degradation model. NPV-over-CAPEX optimal plant designs, tend to favor hybridization, by either collocating wind and solar power with storage, or only solar power with storage. On the hand, minimizing the levelized cost of energy generally results in single-technology power plants. The results show significant potential for hybrid power plants in European markets. However, to truly demonstrate their economic competitiveness, the focus should shift from LCOE to other optimization metrics that consider revenue from different electricity markets.
Economic impact assessment of Hydrogen generated from Offshore Wind: A case study for Belgium
Authors: Gaborieau Maëlig , Yilmaz Ozlem Ceyhan , Dykes Katherine
Published: May 2023

Green hydrogen is increasingly cited as a solution to the decarbonisation of industry. Its large-scale production is still a recent topic with uncertainties. In this paper, an economic impact assessment (EIA) method is explained. A modular and flexible cost model is generated, which estimates the LCOE (Levelized Cost of Energy) of an offshore wind farm and the LCOH (Levelized Cost of Hydrogen) of a hydrogen generation plant either as a hybrid renewable energy system (HRES) or independent from each other. The costs are estimated using a schedule-based approach, which considers the reliability, maintenance operations as well as production of both the offshore wind farm and the hydrogen generation plant. Developed EIA is demonstrated for Belgium using Mermaid Offshore Wind Farm.
Investigation of the dynamic inflow effects due to collective and individual pitch steps on a wind tunnel setup
Authors: Langidis A , Petrović V , Mancini S , Boorsma K , Schepers G , Kühn M
Published: May 2023

Dynamic inflow effects occur due to the rapid change of the rotor loading under conditions such as fast pitch steps. The paper presents a setup suitable for the investigation of those effects for non-axisymmetric rotor conditions, namely individual pitch steps. Furthermore, insights into the relevant phenomena are gathered. An individual pitch control capable model wind turbine is set up in a wind tunnel in order to conduct measurement under controllable conditions. During the execution of the collective and individual pitch steps, the loads and the operational parameters are recorded by the onboard sensors. Meanwhile, simulations engineering aeroelastic codes are run in order to evaluate their accuracy for predicting the relevant phenomena. Results show distinct behaviour of the rotor loads during an individual pitch step, which differs from the loads under collective steps. The free vortex wake simulations are able to predict the turbines’ response satisfactory while the blade element momentum tools show deviations from the measurements. The findings serve as a basis for discussion and future work.
Predictive maintenance of wind turbine’s main bearing using wind farm SCADA data and LSTM neural networks
Authors: Vidal Y , Puruncajas B , Castellani F , Tutivén C
Published: May 2023

Field failures of wind turbine main bearings cause unwanted downtime and significant maintenance costs. Currently, this industry seeks to increase its reliability, for which condition monitoring and predictive maintenance systems have been adopted. In most industrial wind farms, the integrated Supervisory Control and Data Acquisition (SCADA) system provides data that is stored averaged every 10 minutes that can be used to quantify the health of a wind turbine (WT). This research presents a framework for the analysis of data collected from the SCADA system of an operating wind farm, aiming to early detect the main bearing failure using a Long-Short-Term Memory (LSTM) neural network. For prediction, SCADA variables of the temperature of turbine components near the main bearing, rotor speed, ambient temperature, and generated power are taken into account. The results show that the proposed methodology can detect the target failure up to 4 months in advance of the fatal breakdown. The results obtained confirm the applicability of the proposed model in real scenarios that can help the operator with enough time to make more informed maintenance decisions.
Evolution of global snow drought characteristics from 1850 to 2100
Authors: Cowherd Marianne , Ruby Leung L , Girotto Manuela
Published: May 2023

Seasonal snow is an integral part of the global water supply and storage system. Snow droughts impact ecological, agricultural, and urban systems by altering the amount and timing of meltwater delivery. These droughts are characterized by a lack of on-the-ground snow (snow water equivalent, SWE) that can be caused by low total precipitation (dry drought) or low proportion of precipitation falling as snowfall (warm drought), often combined with an early melt. The standardized SWE index (SWEI) ranks the current status of SWE for a given location compared to a baseline condition and identifies the existence, but not the cause, of snow drought. In this work, we use estimates of SWE, temperature, and precipitation from nine coupled model intercomparison project phase 6 (CMIP6) models to quantify the frequency, severity, and type of snow droughts globally for historical and future scenarios. Compared to a historical baseline (1850–1900) total snow drought frequency more than doubles under socio-economic pathway (SSP)2-4.5 and SSP5-8.5; all of the increase in snow drought frequency comes from an increase in warm droughts. The probability distribution of future SWEI in major snowy basins around the world are likely to be centered on more negative values, which corresponds to more severe drought and, with only moderate changes in distribution spread, more frequent drought. CMIP6 simulations pinpoint snow drought as an emerging global threat to water resources and highlight the need to explore higher resolution future models that better capture complex mountain topography, wildland fires, and snow-forest interactions.
Singular relaxation of a random walk in a box with a Metropolis Monte Carlo dynamics
Authors: Chepelianskii Alexei D , Majumdar Satya N , Schawe Hendrik , Trizac Emmanuel
Published: May 2023

We study analytically the relaxation eigenmodes of a simple Monte Carlo algorithm, corresponding to a particle in a box which moves by uniform random jumps. Moves outside of the box are rejected. At long times, the system approaches the equilibrium probability density, which is uniform inside the box. We show that the relaxation towards this equilibrium is unusual: for a jump length comparable to the size of the box, the number of relaxation eigenmodes can be surprisingly small, one or two. We provide a complete analytic description of the transition between these two regimes. When only a single relaxation eigenmode is present, a suitable choice of the symmetry of the initial conditions gives a localizing decay to equilibrium. In this case, the deviation from equilibrium concentrates at the edges of the box where the rejection probability is maximal. Finally, in addition to the relaxation analysis of the Master equation, we also describe the full eigen-spectrum of the Master equation including its sub-leading eigen-modes.
Land suitability study for sweet sorghum (Sorghum bicolor (L.) Moench) farming in Pleret Yogyakarta
Authors: Nurcholis Mohammad , Isdiyanto Rochman , Krismawan Henri , Satria Firman Agung
Published: May 2023

Marginal land and geological disaster-prone in the Opak Fault zone area need to be studied for the basic potential for the development of multi-purpose crops for food, feed, and renewable energy. The study was aimed to determine the potential of the soil and evaluate the suitability of the land for sweet sorghum (Shorgum bicolor) crop in Gunung Kelir, Pleret District, Bantul, Yogyakarta as part of the Opak Fault line. A total of 20 sample points were collected based on geological data, land use, slope, and administrative maps. Analysis of soil physical and chemical properties was carried out to classify soil types and land suitability for sweet sorghum plants. The developing soils in the study area were originated from volcanic breccias, Young Merapi Volcano, and the alluvial of the Opak River, with included in orders of Entisols and Inceptisols. The cation exchange capacity of soils that develop from volcanic breccias is higher than those that develop from Merapi volcanic soils. Suitability of land for sweet sorghum plants includes S2 class with limiting factors for nutrient retention, temperature, and erosion hazard area of ± 24,011 Ha (76.23%), S3 class with limiting factors for erosion hazard and surface stonies of ± 3.85 Ha (12.22%), and N class with a root zone constraint of ± 0.139 Ha (0.44%), and others are not agriculture. Based on the results of this study it is expected that sweet sorghum is able to be developed in the Opak Fault zone to enhance the use of marginal land.
Hydraulic performance of mini polder water management in flood management in Tabalong District, South Kalimantan
Authors: Wibowo Anggara Cahyo , Triadi L. Budi
Published: May 2023

Flood disaster is a common problem, especially in densely populated urban, coastal, and basin areas, respectively. This leads to the development of the Mini Polder design, which is used to solve the problem of flooding in agricultural land. The design is projected in lebak swamp in Ampukung village, Tabalong Regency, Indonesia, covering an area of 393 Ha. Therefore, this study aims to determine the hydraulic performance of mini polders in flood management, within Tabalong District, South Kalimantan, Indonesia. Using Hec-RAS in the planning stage, the results showed that a dike was produced with an elevation and a width of +10.30 and 4 m, based on the Q25th flood discharge of 514.37 m3/s. Furthermore, the construction of a channel around the land was planned as a replacement for the retention pond, due to the efficiency of excavation and stockpiling. The channel also functioned as a flood reducer, which approached water sources to the rice fields or community plantations. By excavating the existing outlet and rehabilitating the door building, the channel normalization was subsequently carried out. For emergency conditions, a portable water pump was needed for water supply and disposal of the Tabalong river, during the arrival of the dry season.
Implementation of forest-land rehabilitation to support the enhancement of carbon stock on Indonesia’s FOLU net sink 2030 strategy
Authors: Dharmawan I W S , Pratiwi
Published: May 2023

Indonesia’s critical land area has a declining trend and in 2018 it was recorded that the critical land area was 14.01 million ha. Efforts to restore critical land through forest-land rehabilitation activities are very important strategy for Indonesia to achieve the FOLU net sink by 2030. This strategy contributes significantly as a sinker for CO2 emissions because it will increase carbon stocks. This study aims to review the implementation as well as contribution of forest-land rehabilitation to support the enhancement of carbon stock on Indonesia’s FOLU net sink 2030. The desk study focused on analyse and review the data on rehabilitation program realization and compare to the target of rehabilitation program achievement in the document of Indonesia’s FOLU net sink 2030. Nationally, the increasing carbon stocks by planting trees through forest-land rehabilitation activities during 2015-2019 has reached a total planting area of 1,183,581 ha or an average planting of 236.716 ha/year. Meanwhile, Indonesia’s FOLU net sink 2030 has a target of increasing carbon stocks of 8,255,323 ha during the 2022-2030 period or an average planting target of 917,258 ha/year. This shows that the contribution of increasing carbon stocks through forest and land rehabilitation is very important, but there is still a gap between the realization of planting for the 2015-2019 period compared to the planting target for 2022-2030 to achieve the FOLU net sink in 2030. This gap can be overcome through the following strategies: 1) selection of priority locations; 2) strong funding support from international and private sectors; 3) community involvement actively through appropriate social forestry mechanisms.