Shortcuts to Thermodynamic Computing: The Cost of Fast and Faithful Erasure

Landauer's Principle states that the energy cost of information processing must exceed the product of the temperature and the change in Shannon entropy of the information-bearing degrees of freedom. However, this lower bound is achievable only for quasistatic, near-equilibrium computations -- that is, only over infinite time. In practice, information processing takes place in finite time, resulting in dissipation and potentially unreliable logical outcomes. For overdamped Langevin dynamics, we show that counterdiabatic potentials can be crafted to guide systems rapidly and accurately along desired computational paths, providing shortcuts that allows for the precise design of finite-time computations. Such shortcuts require additional work, beyond Landauer's bound, that is irretrievably dissipated into the environment. We show that this dissipated work is proportional to the computation rate as well as the square of the information-storing system's length scale. As a paradigmatic example, we design shortcuts to erase a bit of information metastably stored in a double-well potential. Though dissipated work generally increases with erasure fidelity, we show that it is possible perform perfect erasure in finite time with finite work. We also show that the robustness of information storage affects the energetic cost of erasure---specifically, the dissipated work scales as the information lifetime of the bistable system. Our analysis exposes a rich and nuanced relationship between work, speed, size of the information-bearing degrees of freedom, storage robustness, and the difference between initial and final informational statistics.Comment: 19 pages, 7 figures; http://csc.ucdavis.edu/~cmg/compmech/pubs/scte.ht

Efficient Ultrasound Image Analysis Models with Sonographer Gaze Assisted Distillation.

Recent automated medical image analysis methods have attained state-of-the-art performance but have relied on memory and compute-intensive deep learning models. Reducing model size without significant loss in performance metrics is crucial for time and memory-efficient automated image-based decision-making. Traditional deep learning based image analysis only uses expert knowledge in the form of manual annotations. Recently, there has been interest in introducing other forms of expert knowledge into deep learning architecture design. This is the approach considered in the paper where we propose to combine ultrasound video with point-of-gaze tracked for expert sonographers as they scan to train memory-efficient ultrasound image analysis models. Specifically we develop teacher-student knowledge transfer models for the exemplar task of frame classification for the fetal abdomen, head, and femur. The best performing memory-efficient models attain performance within 5% of conventional models that are 1000× larger in size

Applicability of shape parameterizations for giant dipole resonance in warm and rapidly rotating nuclei

We investigate how well the shape parameterizations are applicable for studying the giant dipole resonance (GDR) in nuclei, in the low temperature and/or high spin regime. The shape fluctuations due to thermal effects in the GDR observables are calculated using the actual free energies evaluated at fixed spin and temperature. The results obtained are compared with Landau theory calculations done by parameterizing the free energy. We exemplify that the Landau theory could be inadequate where shell effects are dominating. This discrepancy at low temperatures and high spins are well reflected in GDR observables and hence insists on exact calculations in such cases.Comment: 10 pages, 2 figure

Effect of Time-Delay on a Ratio-Dependent Food Chain Model

This paper aims to study the effect of time-delay on a tritrophic food chainmodel with Michaelis-Menten type ratio-dependent functional responses. Boundednessof the time-delayed system is established. A simple criterion for deterministic extinctionis derived. It has been shown that the time-delay may introduce instability in the systemthrough Hopf bifurcation. Computer simulations are carried out to explain the analyticalfindings. It is discussed how these ideas illuminate some of the observed properties ofreal populations in the field, and explores practical implications

Persistence and Stability of a Food Chain Model with Mixed Selection of Functional Responses

One approach to the study of an ecological community begins with an important object: its food web. Theoretical studies of food web must contend with the question of how to couple the large number of interacting species. One line of investigation assumes that the “building blocks” are species interacting in a pairwise fashion. The model we analyze in this paper describes a tritrophic food chain composed of logistic prey, a classical Lotka-Volterra functional response for prey and predator, and a Holling type-II functional response for predator and superpredator. Dynamical behaviours such as boundedness, stability, persistence, bifurcation et cetera of the model are studied critically. Computer simulations are carried out to explain the analytical findings. Finally it is discussed how these ideas illuminate some of the observed properties of real populations in the field, and explores practical implications

Optical materials based on molecular nano/microcrystals and ultrathin films

Methodologies that we developed recently for the fabrication of molecular crystals with size variation in the nano to micro regime and polyelectrolyte templated mono and multilayer Langmuir-Blodgett films, are reviewed. The electronic absorption and strong fluorescence in the molecular nano/microcrystals are found to be size-dependent. Crystal structure and computational investigations provide a unified model to explain these observations. Role of polyelectrolyte templating in achieving stable and enhanced optical second harmonic generation response from LB films based on a hemicyanine amphiphile is highlighted

Evaluasi Pompa Electric Submersible Pump (Esp) Untuk Optimasi Produksi Pada Sumur P-028 Dan P-029 Di PT. Pertamina Ep Asset 2 Pendopo Field

Setiap sumur produksi yang akan diproduksikan diharapkan fluida akan mengalir kepermukaan secara alami. Proses ini akan berlangsung sampai pada satu titik dimana tekanan reservoir akan berkurang dengan berjalannya waktu, sehingga kemampuan sumur produksi untuk mengangkat fluida ke permukaan akan berkurang atau berhenti sama sekali. Oleh karena itu dibutuhkan metode pengangkatan buatan dimana salah satunya dengan menggunakan pompa ESP. Berdasarkan pengamatan data teknik sumur P-028 dan P-029 sangat cocok untuk diterapkan untuk optimasi produksi. Berdasarkan hasil perhitungan kurva IPR dengan menggunakan metoda Vogel, laju produksi maksimum (Qmaks) yang dicapai sumur P-028 dan P-029 adalah masing–masing sebesar 1211,67 bfpd dan 991,54 bfpd. Selanjutnya melalui pendekatan dengan persamaan empiris didapatkan laju produksi optimum (Qopt) sumur P-028 dan P-029 adalah masing-masing sebesar 969,33 bfpd dan 793,23 bfpd dengan water cut masing–masing 90 % dan 97% maka dihasilkan minyak sebesar 96,93 bopd dan 23,80 bopd. Untuk mencapai laju produksi optimal sumur produksi tersebut maka disarankan pada sumur P-028 untuk mengunakan jenis pompa ESP REDA Type IND 1000 stage sebesar 187 dan range capacity 600-1250 bfpd, Sumur P-029 untuk mengunakan jenis pompa ESP REDA Type IND 750 stage sebesar 141 dan range capacity 400-950 bfpd

Nuclear reaction studies of unstable nuclei using relativistic mean field formalisms in conjunction with Glauber model

We study nuclear reaction cross-sections for stable and unstable projectiles and targets within Glauber model, using densities obtained from various relativistic mean field formalisms. The calculated cross-sections are compared with the experimental data in some specific cases. We also evaluate the differential scattering cross-sections at several incident energies, and observe that the results found from various densities are similar at smaller scattering angles, whereas a systematic deviation is noticed at large angles. In general, these results agree fairly well with the experimental data.Comment: 9 pages, 7 figures, submitted to PR

Exchange bias effect in alloys and compounds

The phenomenology of exchange bias effects observed in structurally single-phase alloys and compounds but composed of a variety of coexisting magnetic phases such as ferromagnetic, antiferromagnetic, ferrimagnetic, spin-glass, cluster-glass and disordered magnetic states are reviewed. The investigations on exchange bias effects are discussed in diverse types of alloys and compounds where qualitative and quantitative aspects of magnetism are focused based on macroscopic experimental tools such as magnetization and magnetoresistance measurements. Here, we focus on improvement of fundamental issues of the exchange bias effects rather than on their technological importance