Fully packed quantum loop model on the square lattice: phase diagram and application for Rydberg atoms

The quantum dimer and loop models attract great attentions, partially because the fundamental importance in the novel phases and phase transitions emerging in these prototypical constrained systems; and partially due to their intimate relevance towards the on-going experiments on Rydberg atom arrays in which the blockade mechanism naturally enforces the local constraint. Here we show, by means of the sweeping cluster quantum Monte Carlo method, the complete ground state phase diagram of the fully packed quantum loop model on the square lattice. We find between the lattice nematic (LN) phase with strong dimer attraction and the staggered phase (SP) with strong dimer repulsion, there emerges a resonating plaquette (RP) phase with off-diagonal translational symmetry breaking. Such a novel phase is separated from the LN via a first order transition and from the SP by the famous Rokhsar-Kivelson point. Our renormalization group analysis reveals the different flow directions, fully consistent with the order parameter histogram in Monte Carlo simulations. The realization and implication of our phase diagram in Rydberg experiments are proposed.Comment: 6+2 pages, 5+2 figure

Measuring incompatibility and clustering quantum observables with a quantum switch

The existence of incompatible observables is a cornerstone of quantum mechanics and a valuable resource in quantum technologies. Here we introduce a measure of incompatibility, called the mutual eigenspace disturbance (MED), which quantifies the amount of disturbance induced by the measurement of a sharp observable on the eigenspaces of another. The MED provides a metric on the space of von Neumann measurements, and can be efficiently estimated by letting the measurement processes act in an indefinite order, using a setup known as the quantum switch, which also allows one to quantify the noncommutativity of arbitrary quantum processes. Thanks to these features, the MED can be used in quantum machine learning tasks. We demonstrate this application by providing an unsupervised algorithm that clusters unknown von Neumann measurements. Our algorithm is robust to noise can be used to identify groups of observers that share approximately the same measurement context.Comment: 14 pages, 2 figure

Effect of Catalytic Cylinders on Autothermal Reforming of Methane for Hydrogen Production in a Microchamber Reactor

A new multicylinder microchamber reactor is designed on autothermal reforming of methane for hydrogen production, and its performance and thermal behavior, that is, based on the reaction mechanism, is numerically investigated by varying the cylinder radius, cylinder spacing, and cylinder layout. The results show that larger cylinder radius can promote reforming reaction; the mass fraction of methane decreased from 26% to 21% with cylinder radius from 0.25 mm to 0.75 mm; compact cylinder spacing corresponds to more catalytic surface and the time to steady state is decreased from 40 s to 20 s; alteration of staggered and aligned cylinder layout at constant inlet flow rates does not result in significant difference in reactor performance and it can be neglected. The results provide an indication and optimize performance of reactor; it achieves higher conversion compared with other reforming reactors

GRACE: Loss-Resilient Real-Time Video through Neural Codecs

In real-time video communication, retransmitting lost packets over high-latency networks is not viable due to strict latency requirements. To counter packet losses without retransmission, two primary strategies are employed -- encoder-based forward error correction (FEC) and decoder-based error concealment. The former encodes data with redundancy before transmission, yet determining the optimal redundancy level in advance proves challenging. The latter reconstructs video from partially received frames, but dividing a frame into independently coded partitions inherently compromises compression efficiency, and the lost information cannot be effectively recovered by the decoder without adapting the encoder. We present a loss-resilient real-time video system called GRACE, which preserves the user's quality of experience (QoE) across a wide range of packet losses through a new neural video codec. Central to GRACE's enhanced loss resilience is its joint training of the neural encoder and decoder under a spectrum of simulated packet losses. In lossless scenarios, GRACE achieves video quality on par with conventional codecs (e.g., H.265). As the loss rate escalates, GRACE exhibits a more graceful, less pronounced decline in quality, consistently outperforming other loss-resilient schemes. Through extensive evaluation on various videos and real network traces, we demonstrate that GRACE reduces undecodable frames by 95% and stall duration by 90% compared with FEC, while markedly boosting video quality over error concealment methods. In a user study with 240 crowdsourced participants and 960 subjective ratings, GRACE registers a 38% higher mean opinion score (MOS) than other baselines

KwaiYiiMath: Technical Report

Recent advancements in large language models (LLMs) have demonstrated remarkable abilities in handling a variety of natural language processing (NLP) downstream tasks, even on mathematical tasks requiring multi-step reasoning. In this report, we introduce the KwaiYiiMath which enhances the mathematical reasoning abilities of KwaiYiiBase1, by applying Supervised Fine-Tuning (SFT) and Reinforced Learning from Human Feedback (RLHF), including on both English and Chinese mathematical tasks. Meanwhile, we also constructed a small-scale Chinese primary school mathematics test set (named KMath), consisting of 188 examples to evaluate the correctness of the problem-solving process generated by the models. Empirical studies demonstrate that KwaiYiiMath can achieve state-of-the-art (SOTA) performance on GSM8k, CMath, and KMath compared with the similar size models, respectively.Comment: technical report. arXiv admin note: text overlap with arXiv:2306.16636 by other author

Waiqi white collars as an obsolete vanguard. Domestic employees of foreign companies in the Chinese discourse on modernization

Yan J. Einheimische Angestellte ausländischer Unternehmen im chinesischen Modernisierungsdiskurs. Berliner Journal für Soziologie . 2022.This research note offers a critical reading of Chinese media reports on highly qualified locals working in Chinese subsidiaries of multinational corporations, also called waiqi white collars. Adopting Laclau and Mouffe's theory of hegemonic discourses and Martin Nonhoff's functional analysis of political discourse, the paper analyzes how this media coverage contributes to the Chinese discourse of identity and national modernization. In particular, it explores how, albeit individual differences, their representation in Chinese media has resulted in a coherent image of waiqi white collars. It is shown that the articulation of waiqi white collar identity is intertwined with the question of how China positions itself within the global world order and how it conceives itself in relation to the so-called "West". The article identifies a palpable shift in the Chinese discourse on modernization in the recent past: in contrast to their former status as a vanguard of modernization, nowadays waiqi white collars are being portrayed in a rather precarious image.Die vorliegende Forschungsnotiz entwickelt eine kritische Lesart chinesischer Medienberichte zu einheimischen Angestellten von in China tätigen multinationalen Unternehmen, auch „waiqi white collars“ genannt. Mit Rückgriff auf den hegemonietheoretischen Diskursansatz von Laclau und Mouffe sowie die von Martin Nonhoff entwickelte funktionale Analyse politischer Diskurse untersucht der Artikel die Operationslogik der Berichte im Rahmen des chinesischen Identitäts- und Modernisierungsdiskurses. Insbesondere wird gefragt, wie sich trotz individueller Unterschiede in der medialen Darstellung ein einheitliches Image der waiqi white collars herauskristallisieren konnte. Es zeigt sich, dass die Identitäten der waiqi white collars in jeweils kontextspezifische Artikulationen eingebunden sind, welche sich zentral auf die Frage beziehen, wie China in der globalen Weltordnung positioniert ist und in welcher Beziehung es zum sogenannten „Westen“ steht. Wie der Artikel darlegt, hat in dieser Hinsicht in der jüngeren Vergangenheit ein manifester Wandel im chinesischen Modernisierungsdiskurs stattgefunden. In der Konsequenz wird der Beschäftigungsgruppe der waiqi white collars heute ein prekäres Image zugeschrieben, im Gegensatz zu ihrem früheren Status als Avantgarde der Modernisierung

Wie kann man die Waiqi white-collars als Gruppe beschreiben? Eine kritische soziologische Untersuchung zur Deutungsaushandlung im Rahmen der Artikulation des chinesischen Modern-Werdens (2012-2018)

Yan J. Wie kann man die Waiqi white-collars als Gruppe beschreiben? Eine kritische soziologische Untersuchung zur Deutungsaushandlung im Rahmen der Artikulation des chinesischen Modern-Werdens (2012-2018). Bielefeld: Universität Bielefeld; 2022

Construction and politicization of waiqi white-collar identity. Traveling knowledge about Chinese professionals in multinational corporations in China

Yan J. Construction and politicization of waiqi white-collar identity. Traveling knowledge about Chinese professionals in multinational corporations in China. InterDisciplines. Journal of History and Sociology. 2017;8(1):81-111.This paper addresses the production of knowledge about highly qualified Chinese working in foreign enterprises in an entangled discourse field. The point of departure for this issue is a critical review of American political scientist Margaret Pearson’s (1997) Study “China's new business elite: The political consequences of economic reform”, exploring its epistemological and ontological assumptions of investigating the attitudes and behaviors of “China´s new business elite”. Furthermore, this paper will also discuss the political-institutional reception conditions under which the knowledge about highly qualified Chinese working in foreign enterprises beyond its US-American production context is transformed into the Chinese discourse on modernization and the middle class. The Chinese interest in this Western scientific knowledge stems less from the necessity of decolonization rather than the appropriation of Western knowledge in order to fit local government´s agenda. Knowledge production of highly qualified Chinese working in MNCs both ways go hand in hand with essentialization and functionalization of the research subject and, disable to recognize the social constructive nature of groups

PARAMETRIC LIFE CYCLE ASSESSMENT OF COMBINED COOLING, HEATING, AND POWER INTEGRATED WITH RENEWABLE ENERGY AND ENERGY STORAGE

Buildings use about 40% of global energy supply, mainly from natural gas and electric grids powered by fossil fuel-based centralized power plants. This study examines a more sustainable energy generation system --- the distributed combined cooling, heating, and power integrated with renewable energy and energy storage system (CCHP-RE-ESS). A parametric hybrid life cycle assessment framework approach is used to evaluate the environmental, economic, and social impacts of the proposed distributed energy generation system. The rationale for a parametric LCA approach is that it extends conventional LCA, which is cases-specific and shows how impacts change with different input factors such as ambient temperature, climate, and operation strategies. The impact results integrate with a multi-objective optimization method, Pareto front, to find the optimal environmental and economic impact trade-offs for different building energy demand scenarios. The parametric framework includes six commercially available trigeneration technologies: two for prime movers (microturbine and fuel cells), two for renewables (solar power and small wind turbine), and two for energy storage (lithium-ion battery and compressed air energy storage). The model is able to find the best combination of technologies and their corresponding sizes for different building demand profiles. After billions of simulations, the Microturbine-Solar PVs-Lithium ion Battery and Fuel Cells-Solar PVs-Lithium-ion Battery are two optimal distributed energy solutions. The simulation impact result shows that the system can primarily reduce the environmental impact as compared to the conventional energy system. However, the life cycle cost of CCHP-RE-ESS is higher than the traditional energy generation, especially for fuel cell-based system.Finally, the model evaluates the social cost and the current U.S. clean energy policy incentives impacts on the distributed CCHP-RE-ESS system. The model uses the Air Pollution Emission Experiments and Policy model to evaluate the marginal damages emissions on a dollar per ton basis. Results show that the social cost of conventional energy is significantly higher than the distributed energy generation. Based on the simulation result, it is estimated that the installation of the distributed CCHP-RE-ESS can help avoid more than 50 billion dollars of social cost per year for commercial buildings in U.S. Besides, the model study the cost-saving potential of current U.S. clean energy policy incentives, including federal tax credit, low-interest loan, and Modified Accelerated Cost Recovery System (MACRS). The tax credit and MACRS can primarily reduce the cost of distributed energy by average 50%, while low-interest loan increases the cost by average 30%. In some scenarios, the after-policy life cycle cost of distributed energy generation is competitive compared to conventional power, but for most situations, the life cycle cost is still higher as compared to conventional power.Ph.D