摘要 ：

We classify all the Hopf PBW-deformations of a new type quantum group U-q(sl(2)*) from which the classical Drinfeld-Jimbo quantum group U-q(sl(2)*) can arise as an almost unique nontrivial one. Different from the U-q(sl(2)*) case, the category of finite-dimensional U-q(sl(2)*)-modules is non-semisimple. We establish a block decomposition theorem for the category U-q(sl(2)*)-mod(wt) of finite-dimensional weight modules of U-q(sl(2)*). On the level of tensor category, we show that U-q(sl(2)*)-mod(wt) (respectively, the category U-q(sl(2))-mod of finite-dimensional U-q(sl(2)*))-modules) can be realized via (respectively, deformed) preprojective algebras of Dynkin type A.

关键词 ：

deformed preprojective algebra weight module block quantum group tensor equivalence PBW-deformation

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Neural network compression is a widely used technique when deploying the neural network in energyconstrained and computation -constrained devices. To guarantee the compressed neural network is still usable without too much accuracy loss, the equivalence between the compressed networks and the original ones must be verified. However, the current verification approach can only verify the equivalence of the two neural networks in the same structure which is limited and unseen in real -world scenarios. In this paper, we proposed an equivalence verification method named VeriPrune, which can verify the equivalence of the deep neural networks without the structure limitation. In detail, we proposed an innovative virtual node completing method to solve the problem that node pruning causes structure change and invalidates the existing equivalence verification approaches. To demonstrate the feasibility and efficiency of the proposed approach, we conducted experiments on the public dataset with 49 DNNs and 1272 properties. The results show that the 83.9% properties, the 1067 of the total 1272 properties can be verified. The proposed VeriPrune can be further developed as a CASE tool for the industry settings.

关键词 ：

Formal verification Equivalence verification Neural network Interval analysis Neural network compression

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A multiscale method is presented to develop a constitutive model for anisotropic soils in a three-dimensional (3D) stress state. A fabric tensor and its evolution, which quantify the particle arrangement at the microscale, are adopted to describe the effects of the inherent and induced anisotropy on the mechanical behaviors at the macroscale. Using two steps of stress mapping, the deformation and failure of anisotropic soil under the 3D stress state are equivalent to those of isotropic soil under the triaxial compression stress state. A series of discrete element method (DEM) simulations are conducted to preliminarily verify this equivalence. Based on the above method, the obtained anisotropic yield surface is continuous and smooth. Then, a fabric evolution law is established according to the DEM simulation results. Compared with the rotational hardening law, the fabric evolution law can also make the yield surface rotate during the loading process, and it can grasp the microscopic mechanism of soil deformation. As an example, an anisotropic modified Cam-clay model is developed, and its performance validates the ability of the proposed method to account for the effect of soil anisotropy.

关键词 ：

soil fabric tensor modified stress anisotropy constitutive model

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A dual-wavelength resolution-matching digital holographic microscopy with one path structured illumination is presented, which can improve phase imaging resolution. In this configuration, a dual-wavelength hologram with two illumination modes corresponding to two different wavelengths can be flexibly recorded at one shot, and the imaging resolutions under the two wavelengths can reach equivalence by setting the modulation frequency of structure illumination. The expression for calculating the modulation frequency of structured illumination in a two-wavelength system is given. By setting the proper modulation frequency, the resolution of dual-wavelength phase imaging can be enhanced, which is verified in the phase imaging experiment of a USAF quantitative phase target. The dual-wavelength reconstructed phase map of paramecia cells exhibit the internal macronucleus, food vacuole and cilia. The imaging results demonstrate the resolution-matching approach using one path structured-illumination in effect for the improvement of phase imaging resolution. © 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.

关键词 ：

Holograms Microscopic examination Phase measurement Frequency modulation

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Ammonia (NH3) is a potential alternative fuel for internal combustion engines to achieve zero-carbon emissions. And partial fuel dissociating is a feasible strategy to improve the reactivity of NH3, the hydrogen (H2) generated by dissociation can effectively promote the combustion of NH3. This study aims to experimentally investigate the ignition and combustion characteristics of partially dissociated NH3 ignited by passive turbulent jet ignition. The effects of the dissociation ratio and equivalence ratio were analyzed. The results show that the dissociation of NH3 improves the ignition and combustion performance of NH3, reflected in lower ignition delay and combustion duration. In addition, as the dissociation ratio increases, the ignition mechanism in the main chamber changes from jet ignition to flame ignition, which can significantly reduce the ignition delay. Lean conditions are more conducive to achieving flame ignition, the jet ignition mechanism on the rich side leads to a higher ignition delay compared to lean conditions at low dissociation ratios. However, the lean mixture shows a higher combustion duration due to its low reactivity. The inhibiting effect of additional nitrogen (N2) increases with the dissociation ratio, but the ignition mechanism and flame propagation in the main chamber are not significantly affected.

关键词 ：

Ammonia Passive pre -chamber Combustion characteristic Partial dissociation Turbulent jet ignition

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The H2/O2 internal combustion is promising to be adopted as auxiliary power by combusting the wasted hydrogen in the upper stages under aerospace conditions. Concerning no inert gases participating the combustion, the control of H2/O2 heat release is a great challenge. This paper proposes to control the heat release by adopting an active pre-chamber (PC). All the combustion consumed oxygen is injected into the PC. The combustion of oxygen and small amount of pre-existed H2 in PC increases the PC pressure, enabling the hot reactant and massive oxygen to be injected into the main chamber (MC) to arrange the oxygen jet induced hydrogen diffusive combustion. The test was conducted on a constant volume combustion bomb (CVCB) to explore the effects of equivalence ratio (phi G) and orifice diameter on the diffusive H2/O2 combustion characteristics. The results showed that increasing phi G resulted in the decreased premix combustion fraction and prolonged combustion duration. The peak pressure of MC dropped with phi G indicating the ability of adjusting engine load by varying phi G. The heat release process could be controlled either by phi G or orifice diameter. Properly increasing the orifice diameter availed shortening the combustion duration and promoting the heat release efficiency.

关键词 ：

Upper Stage Auxiliary Power Units Combustion Jet diffusion Oxygen Hydrogen Internal Combustion Engine

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摘要 ：

The mixture of ammonia (NH3) and hydrogen (H2) is the potential alternative fuel for internal combustion engines (ICEs). The turbulent jet ignition (TJI) system can provide high ignition energy and turbulent disturbance to promote the combustion of the mixture for NH3/H2 ICEs. Therefore, the combustion characteristics of NH3/ H2/air under passive TJI conditions were experimentally studied in the present study. The experiment was conducted in a constant volume combustion bomb, and the effect of fuel composition and equivalence ratio was investigated. The experimental results show that compared to spark ignition, the combustion of NH3/H2 can be effectively improved by using TJI, especially under high NH3 fraction conditions. The addition of H2 has a significant positive effect on the ignition and combustion performance. With the addition of H2, the ignition delay and combustion duration decrease evidently. And the H2 addition is beneficial for improving the ignition mechanism and achieving flame ignition. In addition, poor ignition performance may occur under rich conditions due to the fluid-dynamic quenching of the jet. However, the high flame propagation rate on the rich side still leads to lower combustion duration. Moreover, increasing the orifices number appropriately can enhance the ignition and combustion performance. The jet strength is weakened by the increased total orifice area and the ignition of NH3/H2 can be improved.

关键词 ：

Premixed flame Turbulent jet ignition Ammonia Combustion characteristic Hydrogen

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摘要 ：

Adopting ammonia (NH3) is considered a viable way to reduce carbon emissions. The combustion of NH3/air can be enhanced through the fuel dissociation strategy and the use of turbulent jet ignition (TJI). This study investigated the combustion of partially dissociated NH3 ignited by active TJI. It can be found that the hydrogen (H2) pre-chamber effectively enhances the combustion of partially dissociated NH3, and the appropriate rich prechamber equivalence ratio is beneficial for the main chamber ignition. The lean main chamber mixtures realize the flame ignition mechanism and show a lower ignition delay. The increase in dissociation ratio enhances the tolerance of ignition to turbulence and leads to flame ignition mechanism. The increase in dissociation ratio also enhances the inhibiting effect of additional nitrogen (N2) on combustion, but the ignition mechanism and flame shape are not sensitive to the additional N2.

关键词 ：

Fuel dissociation Ignition characteristics Turbulent jet ignition Ammonia Hydrogen

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摘要 ：

Amid growing environmental concerns, hydrogen (H2) is emerging as a prospective alternative fuel for driving internal combustion engines. Employing lean combustion technology in tandem with turbulent jet ignition (TJI) has the potential to enhance combustion rates while mitigating NOx emissions. Therefore, an experiment was developed to investigate the combustion characteristics of ultra-lean premixed H2/air by TJI. An active prechamber (PC) with an additional H2 supply was selected. Moreover, the effect of nozzle structures and equivalence ratio was discussed. The results show that with a nozzle diameter of 3 mm and an elevation of phi PC to 1.4, the lean flammability limit is extended to an equivalence ratio of 0.13, with a consistently stabilized ignition delay within 4 ms. Increasing the nozzle number also extends the lean flammability limit, but it incurs higher energy losses. Additionally, two ignition mechanisms exist in TJI: flame ignition and combined ignition. The transition from flame ignition to combined ignition commonly occurs when the equivalence ratio of the main chamber drops below 0.3. This transition typically results in higher peak pressures and burnt fuel ratio, lower combustion duration, and longer ignition delay.

关键词 ：

Turbulent jet ignition Active pre-chamber Ignition characteristic Hydrogen Ignition mechanism

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摘要 ：

Ammonia (NH3) is a potential alternative fuel for internal combustion engines, but the disadvantages of low combustion intensity and high nitrogen oxides should be addressed to achieve its application. For NH3 mixture, fuel -rich combustion is a potential method to reduce NOx emissions, and the utilization of turbulent jet ignition (TJI) can enhance its ignition and combustion. Therefore, a strategy of using TJI with assisted oxygen (O2) injection in the pre -chamber to ignite rich NH3/air mixtures was proposed in this study. Considering the lack of relevant research, a fundamental investigation was conducted in this work. The results indicate that the provided method can effectively promote the combustion of NH3/air. The pre -chamber equivalence ratio has no significant effect on the jet strength, but more excess injected O2 enhances the ignition performance of the unburned mixture in the main chamber. The increase of the main chamber equivalence ratio and the decrease of the orifice diameter will result in a higher jet velocity. The ignition of NH3/air is the result of turbulence competing with the reactivity of the mixture. Therefore, high jet velocity leads to poor ignition performance due to the low reactivity of NH3, but appropriate turbulence intensity can promote rapid combustion.

关键词 ：

Turbulent jet ignition Ammonia Combustion characteristic Fuel -rich combustion Oxygen

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