Learning landmark geodesics using the ensemble Kalman filter

<p style='text-indent:20px;'>We study the problem of diffeomorphometric geodesic landmark matching where the objective is to find a diffeomorphism that, via its group action, maps between two sets of landmarks. It is well-known that the motion of the landmarks, and thereby the diffeomorphism, can be encoded by an initial momentum leading to a formulation where the landmark matching problem can be solved as an optimisation problem over such momenta. The novelty of our work lies in the application of a derivative-free Bayesian inverse method for learning the optimal momentum encoding the diffeomorphic mapping between the template and the target. The method we apply is the ensemble Kalman filter, an extension of the Kalman filter to nonlinear operators. We describe an efficient implementation of the algorithm and show several numerical results for various target shapes.</p>

Ecocriticism in Turkey

Ecocriticism has gained visibility in Turkish academia in the early 2000s. This essay offers a brief analysis of the status of the field in Turkey and sheds light on the growing interest in ecology in both academic and non-academic circles. I first overview the academic conventions and publications that provided the initial momentum for the birth of Turkish ecocriticism. I examine past and current trends in ecocritical studies by surveying the latest academic publications, literary works and traditions that lend themselves to ecocritical analyses, and specific ecological questions pertinent to Turkey’s geography. I then address future directions for research in the field and investigate the expanding interest in ecology across different disciplines such as film, visual arts and media. I conclude the essay by highlighting the interdisciplinary platforms that bring together researchers and practitioners to enable new forms of environmental criticism and activism at a time of immense neoliberal growth.

Realizing laminar-like flow in charged bunches with density evolution equations

In the ultra-fast electron microscopy community, electron bunches with much smaller longitudinal widths than transverse widths are emitted from the cathode surface. The community has believed that these bunches evolve to a uniform ellipsoid, but recent simulations by our group and others suggest that if the bunch has an initially transverse Gaussian profile, a ring-like density “shock” emerges at the median of the bunch during evolution. To explain these results, we generalized Reed’s 1D fluid model of charged bunch expansion to cylindrical and spherical geometries demonstrating such a shock emerges analytically under these symmetric geometries. Mathematically, the shock in these models occurs when particles more toward the middle “catch-up” to outer particles, and eventually the trajectory of the more central particle crosses-over the outer particle’s trajectory. This cross-over marks the transition from the laminar to nonlaminar regime. However, this theory has been developed for cold-bunches, i.e. bunches of electrons with zero initial momentum. Here, we briefly review this new theory and extend it to the cylindrically- and spherically-symmetric cases that have nonzero initial momentum. This formulation elucidates how charge-dominated bunches may be manipulated to maintain laminar conditions even through focussing of the bunch.

Investigating Quantum Coherence by Negative Excursions of the Wigner Quasi-Distribution

Quantum information and quantum communication are both strongly based on concepts of quantum superposition and entanglement. Entanglement allows distinct bodies, that share a common origin or that have interacted in the past, to continue to be described by the same wave function until evolution is coherent. So, there is an equivalence between coherence and entanglement. In this paper, we show the relation between quantum coherence and quantum interference and the negative parts of the Wigner quasi-distribution, using the Wigner signed-particle formulation. A simple physical problem consisting of electrons in a nanowire interacting with the potential of a repulsive dopant placed in the center of it creates a quasi two-slit electron system that separates the wave function into two entangled branches. The analysis of the Wigner quasi-distribution of this problem establishes that its negative part is principally concentrated in the region after the dopant between the two entangled branches, maintaining the coherence between them. Moreover, quantum interference is shown in this region both in the positive and in the negative part of the Wigner function and is produced by the superposition of Wigner functions evaluated at points of the momentum space that are symmetric with respect to the initial momentum of the injected electrons.

Study of Waste Bank’s Condition in Semarang City

The development of waste bank is the initial momentum to grow the collective awareness of the community to start sorting, recycling, and utilizing waste because waste has a good selling value, so that the management of environmentally friendly waste becomes Indonesia's new culture. There are several waste bank units in Semarang City, which has not been evenly distributed and the numbers are still relatively small. The purpose of this study is to determine the existing condition of waste banks in Semarang City and the response from the surrounding community. This study uses survey research methods. The technique of collecting data uses in-depth interviews, observation, questionnaires, and documentation. The analysis technique uses quantitative analysis and qualitative analysis. The results showed that in 2018 the number of active waste banks was 44 units spread over 15 sub-districts in Semarang City with an average number of customers of 120 households each waste bank. The main problem found in the management of waste banks is the lack of community interest to become customers of waste banks, as evidenced by only 35% of respondents interested in sorting waste and waste recycling is only carried out by 7% of respondents.

Forensic Engineering Analysis of Unintended Movement of Powered Industrial Trucks

Unintended movement of powered industrial trucks after operators have left the operating position has led to serious — and sometimes fatal — accidents. Even though operators are trained to prevent unintended movement of powered industrial trucks, they can forget to shut off the power source or activate systems to prevent the unintended movement when leaving the truck. Operators are known to make mistakes, especially if they are working in a fast-paced environment and are required to frequently leave the trucks. Engineershave designed electrical interlocks and other systems (e.g., automatically applied parking brakes) to prevent unintended movement; however, not all powered industrial trucks are equipped with them. Furthermore, some of these systems only disconnect the power source from the truck’s drivetrain. These trucks can continue traveling due to their initial momentum or by gravity if the truck was left on a slope. The purpose of this paper is to address the design of forklift operator presence detection systems and unintended movement of unoccupied forklifts through a safety and forensic engineering analysis, highlighting a brief case study to examine the concept of use and foreseeable misuse — and to review the legal concept of strict product liability.

The Effect of Initial Momentum Flux on the Circular Hydraulic Jump

Earlier studies on the circular hydraulic jump have shown that the radial position of the hydraulic jump depends on the flow rate, gravity, and fluid viscosity. In this study, results from numerical simulations and experiments on circular hydraulic jumps are presented and through analysis, it is shown that the momentum flux is an additional controlling parameter in determining the jump location. Apart from the jump location, the variation of the film thickness with flow parameters is also obtained from experiments and numerical simulations. By including the dependence of the momentum flux and dissipation in the film along with other controlling parameters, the data on jump radius obtained from experiments and simulation (including the present study) covering a wide range of parameters reported in the literature can be collapsed on to a single curve.

Frequency measurement using Rayleigh scattering from a BEC

We propose to use superradiant Rayleigh scattering from degenerate Bose gas to detect unknown frequencies coupled to the pump laser beam. Theoretically we show a measurement of the time evolution of population at the initial momentum state could determine the unknown frequency with respect to a known one at which the pump laser's frequency modulates. We show a range of frequencies from kHz to MHz could be determined with this method at the currently available state-of-the-art technology.