Synchronization and Characterization of an Ultra-Short Laser for Photoemission and Electron-Beam Diagnostics Studies at a Radio Frequency Photoinjector

A commercially-available titanium-sapphire laser system has recently been installed at the Fermilab A0 photoinjector laboratory in support of photoemission and electron beam diagnostics studies. The laser system is synchronized to both the 1.3-GHz master oscillator and a 1-Hz signal use to trigger the radiofrequency system and instrumentation acquisition. The synchronization scheme and performance are detailed. Long-term temporal and intensity drifts are identified and actively suppressed to within 1 ps and 1.5%, respectively. Measurement and optimization of the laser's temporal profile are accomplished using frequency-resolved optical gating.Comment: 16 pages, 17 figures, Preprint submitted to Elsevie

What do Work Value Differentiation and Profile Elevation Predict?

Using a sample of 251 college students, it was found that 1) when differentiation (D) of work values was calculated using three indices, high-low D, Iachan D, and variance D, only Iachan D positively related to indecision but high-low D and variance D did not, 2) none of the three indices of D related to career maturity, 3) work values profile elevation (PE) positively related to extraversion, openness, and negatively related to depressive symptoms and career indecision but was unrelated to career certainty and neuroticism and 4) work values PE moderated the relationship between Iachan D and career indecision. The findings from this study benefit both vocational counselors and clients by improving the utility of individuals’ work values results so that they can provide additional information to understand a person’s work values profile

Person-Level Sources of Continued Influence Effect: The Roles of Attention Control, Intolerance of Ambiguity and Conservatism

People continually rely on disinformation to make judgments after it is corrected or discredited. This phenomenon is termed the continued influence effect (CIE). Using a sample of 152 participants, the current study examined whether the CIE can be explained by a person’s political orientation, attention control (AC) levels, intolerance of ambiguity (IA) and need for specific closure (NSC). It was found that when political orientation was based on self-reports, the overall political conservatism did not predict the CIE (r = .13, p = .09) but economic conservatism did (r = .19, p \u3c .05), suggesting that those with higher self-reported fiscally conservative attitudes may show more prolonged influence of disinformation. In addition, the overall AC levels did not predict the CIE (r = .08, p = .30), but the antisaccade scores reflecting the ability to inhibit automatic responses were a significant positive predictor of the CIE (r = .18, p \u3c .05). Lastly, neither IA nor NSC significantly predicted the CIE (ps \u3e .05). These findings were obtained with only one of two measures of the CIE employed, the warehouse fire paradigm (Johnson & Seifert, 1994). Limitations of both the CIE and political orientation measures are discussed. One important implication of this work is that previous research may have depicted an incomplete picture of political orientation, and future studies should aim to capture various aspects of political orientation to further examine the association between various facets of conservatism and the CIE. In addition, more experimental studies should be adopted to better uncover the causal links proposed in this study. These findings may facilitate further exploration and understanding of the sources of the CIE. Keywords: continued influence effect; disinformation; conservatism; attention control; intolerance of ambiguity; need for specific closur

Characterization of Fatigue Damage in Composite Laminate Using Lamb Wave Velocities

Composite laminates suffer from fatigue damage under cyclic loads and one direct result is the stiffness degradation due to transverse matrix cracks in off-axis plies. Since the Lamb wave velocities are decided by the stiffness properties of materials, it is reasonable to use Lamb wave to characterize the fatigue damage in composite laminates. For this to be achieved, an explicit solution for 0-frequency S0 and SH0 mode phase velocities is deduced in this work, based on which a damage evolution law is further proposed combined with shear-lag model and Paris model. The proposed damage evolution law was then used to characterize the fatigue damage in both cross-ply GFRP laminates ([0/903/0/903]s) and quasiisotropic GFRP laminates ([45/0/-45/90]2s), where the experimental S0 phase velocity was obtained by a laser ultrasonic scanning system. The illustrated results in Fig. 1 and Fig. 2 show good agreements between numerical calculations and experimental data. With the proposed damage evolution law, it is possible for future work to be done to inspect and predict the residual fatigue life of composite laminates using Lamb wave velocities

A low-power circuit for piezoelectric vibration control by synchronized switching on voltage sources

In the paper, a vibration damping system powered by harvested energy with implementation of the so-called SSDV (synchronized switch damping on voltage source) technique is designed and investigated. In the semi-passive approach, the piezoelectric element is intermittently switched from open-circuit to specific impedance synchronously with the structural vibration. Due to this switching procedure, a phase difference appears between the strain induced by vibration and the resulting voltage, thus creating energy dissipation. By supplying the energy collected from the piezoelectric materials to the switching circuit, a new low-power device using the SSDV technique is proposed. Compared with the original self-powered SSDI (synchronized switch damping on inductor), such a device can significantly improve its performance of vibration control. Its effectiveness in the single-mode resonant damping of a composite beam is validated by the experimental results.Comment: 11 page

Deep Reinforcement Learning for Wind and Energy Storage Coordination in Wholesale Energy and Ancillary Service Markets

Global power systems are increasingly reliant on wind energy as a mitigation strategy for climate change. However, the variability of wind energy causes system reliability to erode, resulting in the wind being curtailed and, ultimately, leading to substantial economic losses for wind farm owners. Wind curtailment can be reduced using battery energy storage systems (BESS) that serve as onsite backup sources. Yet, this auxiliary role may significantly hamper the BESS's capacity to generate revenues from the electricity market, particularly in conducting energy arbitrage in the Spot market and providing frequency control ancillary services (FCAS) in the FCAS markets. Ideal BESS scheduling should effectively balance the BESS's role in absorbing onsite wind curtailment and trading in the electricity market, but it is difficult in practice because of the underlying coordination complexity and the stochastic nature of energy prices and wind generation. In this study, we investigate the bidding strategy of a wind-battery system co-located and participating simultaneously in both the Spot and Regulation FCAS markets. We propose a deep reinforcement learning (DRL)-based approach that decouples the market participation of the wind-battery system into two related Markov decision processes for each facility, enabling the BESS to absorb onsite wind curtailment while simultaneously bidding in the wholesale Spot and FCAS markets to maximize overall operational revenues. Using realistic wind farm data, we validated the coordinated bidding strategy for the wind-battery system and find that our strategy generates significantly higher revenue and responds better to wind curtailment compared to an optimization-based benchmark. Our results show that joint-market bidding can significantly improve the financial performance of wind-battery systems compared to individual market participation

Semi-Active Vibration Control Based on Switched Piezoelectric Transducers

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