59 research outputs found
Energy Uncertainty Analysis of Electric Buses
Uncertainty in operation factors, such as the weather and driving behavior, makes it difficult to accurately predict the energy consumption of electric buses. As the consumption varies, the dimensioning of the battery capacity and charging systems is challenging and requires a dedicated decision-making process. To investigate the impact of uncertainty, six electric buses were measured in three routes with an Internet of Things (IoT) system from February 2016 to December 2017 in southern Finland in real operation conditions. The measurement results were thoroughly analyzed and the operation factors that caused variation in the energy consumption and internal resistance of the battery were studied in detail. The average energy consumption was 0.78 kWh/km and the consumption varied by more than 1 kWh/km between trips. Furthermore, consumption was 15% lower on a suburban route than on city routes. The energy consumption was mostly influenced by the ambient temperature, driving behavior, and route characteristics. The internal resistance varied mainly as a result of changes in the battery temperature and charging current. The energy consumption was predicted with above 75% accuracy with a linear model. The operation factors were correlated and a novel second-order normalization method was introduced to improve the interpretation of the results. The presented models and analyses can be integrated to powertrain and charging system design, as well as schedule planning.Peer reviewe
Pressure of the Standard Model at High Temperatures
We compute the pressure of the standard model at high temperatures in the
symmetric phase to three loops, or to O(g^5) in all coupling constants. We find
that the terms of the perturbative expansion in the SU(2) + Higgs sector
decrease monotonically with increasing order, but the large values of the
strong coupling constant g_s and the Yukawa coupling of the top quark g_Y make
the expansion in the full theory converge more slowly. The final result is
observed to be about 10% smaller than the ideal gas pressure commonly used in
cosmological calculations.Comment: 30 pages, 4 figures. v2: one reference added, minor revisions,
accepted for publication in JHE
Reducing the energy consumption of electric buses with design choices and predictive driving
Peer reviewe
What Would Be the Principles for Successful Trollbot Design?
As far as we know, trollbots that would be indistinguishable from humans and would succeed in luring people into endless frustrating conflicts without being recognized as bots do not yet exist in social media. It is though very likely, that there is a desire to design one for malicious purposes. Here we speculate on the idea of designing a successful trollbot for research purposes by using concepts that derive from Conversation Analysis and Natural Language Framework. Based on our ongoing reseach on trolling, we argue that a successful trollbot would need to prevent its interlocutor from reaching their goal in a given context, but at the same time manage to keep the other party expecting that they would be able to reach a common ground at some point.Non peer reviewe
Microwave Package Design for Superconducting Quantum Processors
Solid-state qubits with transition frequencies in the microwave regime, such
as superconducting qubits, are at the forefront of quantum information
processing. However, high-fidelity, simultaneous control of superconducting
qubits at even a moderate scale remains a challenge, partly due to the
complexities of packaging these devices. Here, we present an approach to
microwave package design focusing on material choices, signal line engineering,
and spurious mode suppression. We describe design guidelines validated using
simulations and measurements used to develop a 24-port microwave package.
Analyzing the qubit environment reveals no spurious modes up to 11GHz. The
material and geometric design choices enable the package to support qubits with
lifetimes exceeding 350 {\mu}s. The microwave package design guidelines
presented here address many issues relevant for near-term quantum processors.Comment: 15 pages, 9 figure
Characterizing and optimizing qubit coherence based on SQUID geometry
The dominant source of decoherence in contemporary frequency-tunable
superconducting qubits is 1/ flux noise. To understand its origin and find
ways to minimize its impact, we systematically study flux noise amplitudes in
more than 50 flux qubits with varied SQUID geometry parameters and compare our
results to a microscopic model of magnetic spin defects located at the
interfaces surrounding the SQUID loops. Our data are in agreement with an
extension of the previously proposed model, based on numerical simulations of
the current distribution in the investigated SQUIDs. Our results and detailed
model provide a guide for minimizing the flux noise susceptibility in future
circuits.Comment: 14 pages, 6 figure
Impact of ionizing radiation on superconducting qubit coherence
The practical viability of any qubit technology stands on long coherence
times and high-fidelity operations, with the superconducting qubit modality
being a leading example. However, superconducting qubit coherence is impacted
by broken Cooper pairs, referred to as quasiparticles, with a density that is
empirically observed to be orders of magnitude greater than the value predicted
for thermal equilibrium by the Bardeen-Cooper-Schrieffer (BCS) theory of
superconductivity. Previous work has shown that infrared photons significantly
increase the quasiparticle density, yet even in the best isolated systems, it
still remains higher than expected, suggesting that another generation
mechanism exists. In this Letter, we provide evidence that ionizing radiation
from environmental radioactive materials and cosmic rays contributes to this
observed difference, leading to an elevated quasiparticle density that would
ultimately limit superconducting qubits of the type measured here to coherence
times in the millisecond regime. We further demonstrate that introducing
radiation shielding reduces the flux of ionizing radiation and positively
correlates with increased coherence time. Albeit a small effect for today's
qubits, reducing or otherwise mitigating the impact of ionizing radiation will
be critical for realizing fault-tolerant superconducting quantum computers.Comment: 16 pages, 12 figure
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