Combining TT* argument and bilinear interpolation,this paper obtains the Strichartz and smoothing estimates of dispersive semigroup e^(-itP(d)) in weighted L^(2) *** other things,we recover the results in[1].Moreover,...
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Combining TT* argument and bilinear interpolation,this paper obtains the Strichartz and smoothing estimates of dispersive semigroup e^(-itP(d)) in weighted L^(2) *** other things,we recover the results in[1].Moreover,the application of these results to the well-posedness of some equations are shown in the last section.
This study was to establish an efficient strategy based on inoculum-morphology control for the submerged mycelial fermentation of an edible and medicinal fungus, Inonotus hispidus. Two major morphological forms of the...
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This study was to establish an efficient strategy based on inoculum-morphology control for the submerged mycelial fermentation of an edible and medicinal fungus, Inonotus hispidus. Two major morphological forms of the mycelial inoculum were compared, dispersed mycelial fragments versus aggregated mycelial clumps. The dispersed one was more favorable for the fermentation, starting with a shorter lag period and attaining a higher biomass yield and more uniform mycelium pellets in shake flasks. The mycelial pellets taken from the shake flask culture on day 6 were fragmented at 26,000 rpm in a homogenizer, and a shear time of 3 min provided the optimal inoculum. The inoculum and culture conditions were further verified in 5-L stirred tank fermenters and then the fermentation was scaled-up in a 100-L stirred tank. With the optimized inoculum and process conditions plus a fed-batch operation, much higher productivities, including 22.23 g/L biomass, 3.31 g/L EPS, and 5.21 g/L IPS, were achieved in the 100-L fermenter than in the flask culture. A composition analysis showed that the I. hispidus mycelium produced by the fermentation was rich in protein, dietary fiber, and polysaccharides which may be beneficial to health. Overall, the results have shown that the inoculum characteristics including age, morphology, and state of aggregation have significant impact on the productivity of mycelial biomass and polysaccharides in a submerged mycelial fermentation of the I. hispidus fungus.
Hydrodynamic seals are crucial sealing components in aero-engines, and the wear phenomenon during their start-up process is the primary cause of engine efficiency and lifetime degradation. To accurately predict the we...
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Hydrodynamic seals are crucial sealing components in aero-engines, and the wear phenomenon during their start-up process is the primary cause of engine efficiency and lifetime degradation. To accurately predict the wearrate of seals, this study establishes a wear prediction model for the start-up process of hydrodynamic seals. The model solves the multi-field coupling of cross-scale contact mechanics and hydrodynamics, and calculates the wearrate of seals using the Modified Archard Wear Equation. The model's accuracy is verified through tests, and the study analyzes the influence of the force balance coefficients of the seal on the wearrate. It was observed that (i) hydrodynamic seals experience a wear-increase stage, a wear-decrease stage, a transition stage, and a no-wear stage during the start-up process;(ii) increasing the static load factor helps to reduce the duration of the wear stage;(iii) as the gap convergence rate increases, the wear-increase stage compresses the durations of the other stages, followed by the wear-decrease stage, which compresses and then decompresses the durations of the other stages;(iv) as the gap convergence rate increases from 0.00 to 6.00 x 10-6, the main wear area shifts from the outer side to the inner side;(v) increasing the spring load factorraises the wearrate anddiminishes the influence of both the static load factor and the gap convergence rate.
作者：
Song, ChenghuaWang, YinWang, LintaoWang, JianweiFu, XinChangan Univ
Coll Transportat Engn Xian Peoples R China Changan Univ
Coll Econ & Management Xian Peoples R China Changan Univ
Minist Educ Xian Peoples R China Changan Univ
Key Lab Integrated Transportat Big Data & Intellig Xian Peoples R China Changan Univ
Coll Transportat Engn Xian 710064 Peoples R China Changan Univ
Engn Res Ctr Highway Infrastructure Digitalizat Minist Educ Xian 710064 Peoples R China Changan Univ
Key Lab Integrated Transportat Big Data & Intellig Xian 710064 Peoples R China
Map matching is a fundamental prerequisite for traffic engineers in detecting congestion using location data represented by trajectory data. Previous studies often revolve aroundroad matching, yet limitations arise f...
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Map matching is a fundamental prerequisite for traffic engineers in detecting congestion using location data represented by trajectory data. Previous studies often revolve aroundroad matching, yet limitations arise from trajectory data quality and map-matching accuracy. This paper introduces a map-independent congestion identification method, involving urban cell network construction, congestion modeling with speed fluctuations, and the exploration of congestion evolution patterns. Finally, we validated our proposed method using Floating Taxi data (FTd) from Xi'an, china. The result indicates that the method proposed in this study can identify urban traffic congestion and uncover its evolutionary characteristics without relying on maps. In contrast to other metrics, the customized congestion value considers the impact of speed fluctuations on congestion. The method proposed in this paper offers a benchmark solution for characterizing urban traffic congestion and formulating travel guidelines.
In this work, an improved wall boiling model for nanofluids was proposed, taking into account the effect of bubble slip on the wall heat flux density, as well as the effects of nanofluid thermophysical properties and ...
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In this work, an improved wall boiling model for nanofluids was proposed, taking into account the effect of bubble slip on the wall heat flux density, as well as the effects of nanofluid thermophysical properties and nanoparticle deposition on the density of nucleation sites and bubble departure diameter. The nucleation site density and bubble departure diameter were calculated and compared with the experimental data, the deviations were not more than 7.80% and 9.81%, respectively. The downward-facing surface's critical heat flux (CHF) was numerically simulated using Al2O3-H2O nanofluids. The simulation results of CHF were compared with the experimental data, and the maximum deviation did not exceed +/- 16.9%. Compared to pure water, the average CHF enhancement of 0.001-0.01vol% Al2O3-H2O nanofluid was 65.4%. The impacts of thermophysical properties, contact angle, and surface roughness were analyzed separately using the control variable method. The results showed that the wall temperature and void fraction were mostly not affected by thermophysical properties, and the variation in contact angle and surface roughness had a substantial impact. For the CHF improvement of 0.001vol% Al2O3-H2O nanofluids, the proportions of contact angle, surface roughness, and thermophysical properties on the CHF enhancement are 57%, 8%, and 1%. CHF enhancement with nanofluid was strongly related to the changes in contact angle and surface roughness.
Enterprise risk assessment not only provides a crucial reference for enterprises' strategic and business decisions, but also forms a fundamental basis for the financing decisions of banks and other financial insti...
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Enterprise risk assessment not only provides a crucial reference for enterprises' strategic and business decisions, but also forms a fundamental basis for the financing decisions of banks and other financial institutions. Furthermore, as a critical node within the industrial chain, the enterprise's risk may directly affect the stability of the entire industrial chain, highlighting the significance of researching enterprise risk assessment. Existing enterprise risk assessment methods need to be revised to account for the risk transmission between enterprises across different types of relationships. Consequently, it leads to the need for more utilization of industrial chain structure and interaction information between enterprises. To address this problem, an enterprise risk assessment model, which is based on attention mechanism and graph network, is proposed. Firstly, weights of associated enterprises under a particularrelationship are focused on. Then, weights of different relationships are introduced. After that, feature aggregation is conducted. Finally, features are put into the classification network to determine the risk category of the target enterprise, and enterprise risk assessment is accomplished. Experiments using dataset in integrated circuit industrial chain are conducted to verify this method, and the result shows that the method can effectively assess enterprise risk.
diamond turning based on tool servos is gaining applications increasingly in the surface forming of complex-shaped optics. However, current fast/slow tool servo techniques encounter inherent limitations in terms of st...
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diamond turning based on tool servos is gaining applications increasingly in the surface forming of complex-shaped optics. However, current fast/slow tool servo techniques encounter inherent limitations in terms of stroke or bandwidth, posing a significant challenge for high-precision and high-efficiency machining of structures with relatively large strokes. To handle this dilemma, this study proposes a master-slave coordinated control strategy for fast and slow cooperative tool servo diamond turning. Specifically, the slow tool servo (STS) serves as the master servo to follow the desired toolpath, while an additional fast tool servo (FTS) axis acts as the slave servo to track the motion error of the master servo in real time. To enhance the tracking performance of the slave servo, a frequency response data-based enhancedreal-time iterative compensation method is developed to control the fast axis. As a validation, the ultraprecision diamond turning experiments are conducted on a three-axis lathe equipped with a custom-designed FTS. The servo motion is performed with high accuracy and a microlens array is generated with high quality, suggesting that the proposed strategy effectively eliminates the motion errors of the STS and significantly improves the form accuracy of the fabricated surfaces.
Phenol formaldehyde resin (PFr) has been widely used in many fields, including adhesion, refractory, coating, mold, and foam plastics. However, with the depletion of fossil fuels and more concerns on carbon neutral in...
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Phenol formaldehyde resin (PFr) has been widely used in many fields, including adhesion, refractory, coating, mold, and foam plastics. However, with the depletion of fossil fuels and more concerns on carbon neutral in recent years, the application of bio-oil to prepare bio-oil formaldehyde resin (BFr) forreplacing phenol with bio-oil is arousing great interest, which is beneficial forreducing the carbon emission and the production cost. However, the thermal stability of BFr is far from satisfactory. More flammable and toxic volatile substances will be released from BFr than from PFr, which strongly poses safety and healthy risks to the fabricating workers and the users of the resin. In this work, the thermal stability of BFr is investigated by TG and Py-GC/MS methods, for better understanding the reasons behind the low thermal stability of BFr and for improving the thermal stability of the resin. The content of phenols and the presence of some non-phenolic compounds in bio-oil, as well as the catalyst dosage of NaOH, are studied. It is found that acetic acid has a strong inhibiting role to the reaction. The addition of NaOH can improve the thermal stability, but a large amount of NaOH may reversely promote the release of volatile matters. The separation of acetic acid before polymerization is a better choice than the addition of more NaOH. The reaction is found more complex beyond the factors discussed, so more parameters such as the curing conditions are necessary for further investigations in future work.
Predicting reliability is an essential part of the design phase for ensuring mission success. In the realm of gravitational wave detection, the integrity anddependability of the Grabbing, Positioning, andrelease Mec...
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Predicting reliability is an essential part of the design phase for ensuring mission success. In the realm of gravitational wave detection, the integrity anddependability of the Grabbing, Positioning, andrelease Mechanism (GPrM) are paramount for its effective space-baseddeployment. However, predicting reliability of a complex mechanical system like the GPrM during the design phase poses significant challenges due to the harsh and variable conditions of the space environment. This paper addresses these challenges by proposing a reliability evaluation method that combines the stochastic anddegradation characteristics of the GPrM, according to which both randomness of the stud position and the degradation of the piezoelectric coefficient are considered. Failure criteria are established based on mission performance indicators, and the Kaplan-Meier estimator is used to analyze the mechanism reliability of the GPrM over time. The result predicts that the reliability of the GPrM is around 0.8 after 107 operating cycles. This finding demonstrates that our proposed method is an effective approach for evaluating reliability, offering valuable insights for ensuring the long-term performance and successful operation of precision mechanisms.
The structured quaternion linear systems are hot research topics in engineering and scientific computations, especially they have important applications in signal and image processing. In this article, we consider the...
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The structured quaternion linear systems are hot research topics in engineering and scientific computations, especially they have important applications in signal and image processing. In this article, we consider the quaternion Toeplitz-type linear systems arising from color image processing. Firstly, we explore the quaternion conjugate gradient normal residual (QCGNr) method for solving such structured quaternion linear systems, in which the Toeplitz or block Toeplitz structure is used to achieve the fast computation of quaternion matrix-vector products. Secondly, to accelerate the convergence of the iterative method, we propose two preconditioned QCGNr iterative methods with the quaternion circulant or block-circulant preconditioner. Finally, numerical experiments given by both random data andreal worlddata show the feasibility and effectiveness of the proposed methods.
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