The performance of baseball and softball bats can depend strongly on the properties of the ball. Standard test methods exist to measure the ball weight, hardness and coefficient of restitution (COR). ...Ball hardness is measured in a quasistatic compression test and the COR is measured by impacting the ball against a rigid plate. Little has been done to determine how these properties relate to the measurement of high speed bat-ball impacts. This study considers the rate dependence of ball compression, COR, degradation from multiple impacts, and humidity. A dynamic compression test, where the ball impacts a rigidly mounted load cell, was used to compare static and dynamic compression. The balls were tested as a function of speed to determine the appropriateness of extrapolating low speed test results to high speed play conditions. The compression and COR of balls conditioned to dry and humid environments were compared to determine if humidity can be used to control ball hardness in laboratory tests. A strong correlation between the static and dynamic ball hardness was observed, although the correlation involved an offset. The frequency of ball testing (which is not controlled in any standard) was observed to affect the ball's measured response. The change in the ball's response was temporary and found to be related to its temperature and viscoelasticity. The response of balls impacted 100 times was nearly unchanged when allowed to recover between tests. Humidity was observed to have a negligible effect on a ball's COR and dynamic hardness, but a measurable effect on its static hardness.
Active longitudinal beam optics can help FEL facilities achieve cutting edge performance by optimizing the beam to: produce multi-color pulses, suppress caustics, or support attosecond lasing. As the ...next generation of superconducting accelerators comes online, there is a need to find new elements which can both operate at high beam power and which offer multiplexing capabilities at Mhz repetition rate. Laser heater shaping promises to satisfy both criteria by imparting a programmable slice-energy spread on a shot-by-shot basis. We use a simple kinetic analysis to show how control of the slice energy spread translates into control of the bunch current profile, and then we present a collection of start-to-end simulations at LCLS-II in order to illustrate the technique.
Operating large-scale scientific facilities often requires fast tuning and robust control in a high dimensional space. In this paper we introduce a new physics-informed optimization algorithm based ...on Gaussian process regression. Our method takes advantage of the existing domain knowledge in the form of realizations of a physics model of the observed system. We have applied a physics-informed Gaussian Process method experimentally at the SPEAR3 storage ring to demonstrate online accelerator optimization. This method outperforms Gaussian Process trained on data as well as the standard approach routinely used for operation, in terms of convergence speed and optimal point. The proposed method could be applicable to automatic tuning and control of other complex systems, without a prerequisite for any observed data.
High-dimensional optimization is a critical challenge for operating large-scale scientific facilities. We apply a physics-informed Gaussian process (GP) optimizer to tune a complex system by ...conducting efficient global search. Typical GP models learn from past observations to make predictions, but this reduces their applicability to new systems where archive data is not available. Instead, here we use a fast approximate model from physics simulations to design the GP model. The GP is then employed to make inferences from sequential online observations in order to optimize the system. Simulation and experimental studies were carried out to demonstrate the method for online control of a storage ring. We show that the physics-informed GP outperforms current routinely used online optimizers in terms of convergence speed, and robustness on this task. The ability to inform the machine-learning model with physics may have wide applications in science.
...my first hand encounters with animals and industry workers disproved negative misconceptions I had previously held about meat production and improved my interest in Animal Science as a career.\n I ...gained access to advantaged information and I am grateful to have been given insight to the challenges graduate students commonly encounter in their first years of research. To be successful in research, a student must be self-motivated, willing to become thoroughly familiar with scientific literature and communicate effectively with others in a concise, meaningful way. ...faculty mentors often handpick URE students observed to be capable and enthusiastic because they must donate time outside of class and demonstrate patience by allowing for mistakes and learning to take place (Dodson, 1997; Seymour et al., 2003).
In this paper, we present a new kind of high power and high efficiency free-electron laser oscillator based on the application of the tapering enhanced stimulated superradiant amplification (TESSA) ...scheme. The main characteristic of the TESSA scheme is a high intensity seed pulse which provides high gradient beam deceleration and efficient energy extraction. In the oscillator configuration, the TESSA undulator is driven by a high repetition rate electron beam and embedded in an optical cavity. A beam-splitter is used for outcoupling a fraction of the amplified power and recirculate the remainder as the intense seed for the next electron beam pulse. The mirrors in the oscillator cavity refocus the seed at the undulator entrance and monochromatize the radiation. In this paper we discuss the optimization of the system for a technologically relevant example at 1 \(\mu\)m using a 1~MHz repetition rate electron linac starting with an externally injected igniter pulse.
The generation of X-rays and {\gamma}-rays based on synchrotron radiation from free electrons, emitted in magnet arrays such as undulators, forms the basis of much of modern X-ray science. This ...approach has the drawback of requiring very high energy, up to the multi-GeV-scale, electron beams, to obtain the required photon energy. Due to the limit in accelerating gradients in conventional particle accelerators, reaching high energy typically demands use of instruments exceeding 100's of meters in length. Compact, less costly, monochromatic X-ray sources based on very high field acceleration and very short period undulators, however, may revolutionize diverse advanced X-ray applications ranging from novel X-ray therapy techniques to active interrogation of sensitive materials, by making them accessible in cost and size. Such compactness may be obtained by an all-optical approach, which employs a laser-driven high gradient accelerator based on inverse free electron laser (IFEL), followed by a collision point for inverse Compton scattering (ICS), a scheme where a laser is used to provide undulator fields. We present an experimental proof-of-principle of this approach, where a TW-class CO2 laser pulse is split in two, with half used to accelerate a high quality electron beam up to 84 MeV through the IFEL interaction, and the other half acts as an electromagnetic undulator to generate up to 13 keV X-rays via ICS. These results demonstrate the feasibility of this scheme, which can be joined with other techniques such as laser recirculation to yield very compact, high brilliance photon sources, extending from the keV to MeV scale. Furthermore, use of the IFEL acceleration with the ICS interaction produces a train of very high intensity X-ray pulses, thus also permitting a unique tool that can be phase-locked to a laser pulse in frontier pump-probe experimental scenarios.
Influence of location on land evaluation Duris, J; Latecka, M. (Slovenska Polnohospodarska Univ., Nitra (Slovak Republic))
Acta horticulturae et regiotecturae,
(Oct 2002), Letnik:
5, Številka:
2
Journal Article
Recenzirano
The paper describes a method for use of outputs of the approved project of renewed land registration for the purposes of differentiated land evaluation in terms of land location using the ...municipality distance coefficient. Evaluation and price adjustment of agricultural land by municipality distance coefficients was investigated in 100 chosen original lands up to a 3,000 m distance, with the area of 1,229.29 ha of Oponice cadastre territory. The results indicated that official prices do not reflect the significant differences connected with a different location of lands, which has the adverse influence on the land adjustment process in particular. Nowadays the coefficients of price adjustment of agricultural land are not still laid down in legislation. However, the price of agricultural land adjusted by municipality distance coefficients will make it possible to fix more objectively the price of the particular allotment
