Product State Research Articles

Modelling of foundation damping in time-domain analysis of monopile supported offshore wind turbine structures

Foundation damping holds large potential for design optimisations of monopile-supported offshore wind turbine structures. However, the contribution of foundation damping is not well understood, in part due to lack of suitable method for incorporating foundation damping in the time-domain analysis of wind turbine structures. This paper presents a practical approach for this purpose in which a dashpot is attached in parallel to each p-y spring along the monopile. In this way, the distributed soil-pile interaction stiffness and damping are accurately modelled. To demonstrate the validity of the proposed approach, a case study exploring the influence of foundation damping on the dynamic response of an IEA 15 MW reference turbine founded on monopile is carried out. The results demonstrate that the foundation damping has relatively limited impact on the overall dynamic response and fatigue loads in power production states. However, inclusion of foundation damping is shown to significantly reduce the structural response after emergency shutdown and under parked conditions. The findings of the case study show promising potential for wind turbine structure design optimization through consideration of foundation damping.

Assessing the Impact of Voluntary Certification Schemes on Future Sustainable Coffee Production

Coffee production faces major sustainability issues and consumers increasingly look to choose certified coffee as awareness grows. While consumers’ understanding of sustainability issues is limited, independent voluntary certification schemes such as Fairtrade, Rainforest Alliance, and certified organic—three high-profile schemes—can play a role in future-proofing coffee production through standard-setting. These schemes can also inform consumers about sustainability issues from economic, environmental, and social perspectives, thus driving up demand for sustainably grown coffee, and supporting an enabling environment for farmers and coffee-producing countries to improve the status quo. Sustainably grown coffee ensures that farmers sustain production while protecting the environment and the income that farmers rely on to maintain their livelihood. Based on a thematic analysis and synthesis of previous studies, this paper examines the social, economic, and environmental effects of voluntary certification schemes for coffee production. It evaluates the current state of coffee production and explores how certification schemes can be effective in encouraging more sustainable practices among producers. Three major voluntary certification schemes are evaluated to identify the impacts on producers, including key barriers and enablers to comply with sustainability standards and to determine how fit-for-purpose certification schemes are in assuring future sustainable coffee production.

Discrete higher Berry phases and matrix product states

Discrete higher Berry phases and matrix product states

Temporal entropy and the complexity of computing the expectation value of local operators after a quench

We study the computational complexity of simulating the time-dependent expectation value of a local operator in a one-dimensional quantum system by using temporal matrix product states(MPSs) and argue that it is intimately related to that of encoding temporal transition matrices and their partial traces. We show that we can upper-bound the rank of these reduced transition matrices by one of the Heisenberg evolution of local operators, thus making aconnection between two apparently different quantities, the temporal entanglement and the local operator entanglement(OE). As a result, whenever the local OE grows slower than linearly in time, we show that computing time-dependent expectation values of local operators using temporal MPSs is likely advantageous with respect to computing the same quantities using standard MPS techniques. Published by the American Physical Society 2024

Approximate encoding of quantum states using shallow circuits

Quantum algorithms and simulations often require the preparation of complex states through sequences of 2-qubit gates. For a generic quantum state, the number of required gates grows exponentially with the number of qubits, becoming unfeasible on near-term quantum devices. Here, we aim at creating an approximate encoding of the target state using a limited number of gates. As a first step, we consider a quantum state that is efficiently represented classically, such as a one-dimensional matrix product state. Using tensor network techniques, we develop and implement an efficient optimization algorithm that approaches the optimal implementation, requiring a polynomial number of iterations. We, next, consider the implementation of the proposed optimization algorithm directly on a quantum computer and overcome inherent barren plateaus by employing a local cost function. Our work offers a universal method to prepare target states using local gates and represents a significant improvement over known strategies.

Tree hollow decline in new forest reserves with a long history of logging

AbstractIn many parts of the world, achieving a target of 30% of land managed for conservation under the Kunming‐Montreal Global Biodiversity Framework will require the protection of land with a long history of management for production. In newly protected forests, past logging practices will have impacted key aspects of stand structure, including hollow‐bearing trees that provide critical habitat for vertebrate fauna. The impacts of past silvicultural practices on hollow density, distribution, type and longevity may necessitate targeted ameliorative actions. We investigated tree hollows in the largest river red gum (Eucalyptus camaldulensis Denh.) forest in the world, which had undergone logging‐induced woody thickening prior to being converted to a conservation reserve in 2010. We recorded stem diameters and hollows in living and dead trees in 66 two‐hectare plots. Our sites sampled two productivity states and a wide range of total tree densities. On all sites, we found that hollow‐bearing tree densities were lower than reference values for unlogged stands and average density had halved relative to reference values. We found no relationship between the density of hollow‐bearing trees and total tree density, but we did find a weak positive relationship with site productivity. Larger trees had more hollows, bigger hollows and a greater diversity of hollow sizes. However, of the 1254 hollow‐bearing trees recorded, 43% were dead, 48% of the dead trees had been ringbarked. The proportion of hollow‐bearing trees that were dead was positively correlated with tree size, with 60% of trees in the largest quartile (>105 cm) recorded as dead. The prevalence of dead hollow‐bearing trees suggests that the density and diversity of hollows will continue to decline and ameliorative actions should be considered. These results highlight the need to consider the legacy of past silvicultural practices in the management of newly created conservation reserves.

Heterogeneous bacterial communities in gills and intestine of Nile tilapia (Oreochromis niloticus) and in water and sediments of aquaculture ponds in Bangladesh

Tilapia aquaculture contributes significantly to the nutritional requirements of humans. Because microbes play a pivotal role in maintaining the host's physiology and biochemistry, research on the microbiomes associated with tilapia and in the rearing pond water and sediment can contribute to increased production. We applied 16S rRNA gene amplicon sequencing to elucidate the bacterial community structures in the gills and intestine of Nile tilapia as well as in the water and sediment of their rearing ponds. We identified a total of 9770 bacterial Operational Taxonomic Units (OTUs) in all the samples. The sediment samples, which generated 3884 unique OTUs, had the highest level of alpha-diversity (Shannon index, P < 0.01) among all the samples. Fusobacteria (59%) predominated and constituted the indicator phylum in tilapia gills, while Proteobacteria was prevailed in water (52%), sediment (28%), and intestine (33%). The bacterial community structures of the gills and intestine were not much similar to those of the surrounding water and sediment, probably due to host-specific microbial selection. More than 70% of the bacterial flora were beneficial, whereas nearly 10% were pathogenic in gills and intestine of tilapia. This study aims to explore the microbiome of tilapia aquaculture in Bangladesh, and the results suggest that the microbial communities in tilapia gills and intestine are in a eubiotic state, which indicates a healthy state for better growth and production of Nile tilapia aquaculture.

Production and dissemination path of new media film and television content based on 5G technology

Using new media to enhance the visual and creative quality of cinema and television works may also give a new means for the general public to create and distribute these works, improving the ease of film and television production and distribution. This paper studies the production and dissemination paths of new media film and television content based on 5G technology and then uses neural networks to evaluate the effectiveness of the method and complete the following work: 1) To begin, we’ll discuss the current state of new media film and television production and distribution research both domestically and internationally. 2) The development approach of film and television production and dissemination under the new media environment is proposed. The basic principles of BPNN and PSO are introduced, and then the PSO-BP model is constructed. 3) Collect the experimental data set and then select the optimal parameters of the model through experiments. The experimental results obtained by inputting the test data into the model are compared with the actual values, and it is found that the error between the estimated value of the model and the exact value is tiny.

Awareness and adoption of farm biosecurity practices in commercial dairy, pig and poultry farms of Uttar Pradesh (India).

India's livestock sector has been facing significant losses due to episodes of disease outbreaks since time immemorial. Hence, biosecurity measures are very important to maintain and improve animal health along with prevention of disease outbreak. Keeping these facts into consideration, the study was proposed with an objective to assess the existing biosecurity practices adopted by the commercial dairy, pig and poultry farms. The current study was undertaken in the state of Uttar Pradesh as it is the leading state in milk and meat production. A total of 120 farmers were selected randomly including 40 each practicing commercial dairy, pig and poultry farming. An ex-post facto research methodology was used with face-to-face interview and observation to collect data. The biosecurity practices were assessed under seven dimensions such as, location and design of farm, restricted access, isolation and quarantine, cleaning and disinfection, management of feed and water, disposal of carcass, manure and waste, and health management. Results elicited that about 50% of the farmers had medium level of adoption who adopted 18-34 practices out of 51 practices. The average overall adoption score was 34.17 out of 51 (67%) which makes an overall adoption gap of 33%. Maximum adoption gap was seen in case of restricted access (43%) whereas minimum gap in adoption was seen in case of management of feed and water (27%). Pig and poultry farmers showed significantly higher biosecurity measures than dairy farmers (p < 0.05). The more significant contributors to the adoption of biosecurity measures were the level of knowledge of the farmers (p < 0.01). Other factors such as education, income, herd/flock size, Information and Communication Technology utilization, number of trainings also had a significant contribution (p < 0.05) in actual implementation of biosecurity. Hence, better understanding of these measures among the farmers must be ensured by hands on training along with proper demonstration of various procedures involved in maintaining farm biosecurity is need of the hour.

Unveiling the Stabilizer Group of a Matrix Product State.

We present a novel classical algorithm designed to learn the stabilizer group-namely, the group of Pauli strings for which a state is a ±1 eigenvector-of a given matrix product state (MPS). The algorithm is based on a clever and theoretically grounded biased sampling in the Pauli (or Bell) basis. Its output is a set of independent stabilizer generators whose total number is directly associated with the stabilizer nullity, notably a well-established nonstabilizer monotone. We benchmark our method on T-doped states randomly scrambled via Clifford unitary dynamics, demonstrating very accurate estimates up to highly entangled MPS with bond dimension χ∼10^{3}. Our method, thanks to a very favorable scaling O(χ^{3}), represents the first effective approach to obtain a genuine magic monotone for MPS, enabling systematic investigations of quantum many-body physics out of equilibrium.

Nonstabilizerness versus entanglement in matrix product states

Nonstabilizerness versus entanglement in matrix product states

Long-time properties of generic Floquet systems are approximately periodic with the driving period

A Floquet quantum system is governed by a Hamiltonian that is periodic in time. Consider the space of piecewise time-independent Floquet systems with (geometrically) local interactions. We prove that for all but a measure zero set of systems in this space, starting from a random product state, many properties (including expectation values of observables and the entanglement entropy of a macroscopically large subsystem) at long times are approximately periodic with the same period as the Hamiltonian. Thus, in almost every Floquet system of arbitrarily large but finite size, discrete time-crystalline behavior does not persist to strictly infinite time.

Nonstabilizerness via Matrix Product States in the Pauli Basis.

Nonstabilizerness, also known as "magic," stands as a crucial resource for achieving a potential advantage in quantum computing. Its connection to many-body physical phenomena is poorly understood at present, mostly due to a lack of practical methods to compute it at large scales. We present a novel approach for the evaluation of nonstabilizerness within the framework of matrix product states (MPSs), based on expressing the MPS directly in the Pauli basis. Our framework provides a powerful tool for efficiently calculating various measures of nonstabilizerness, including stabilizer Rényi entropies, stabilizer nullity, and Bell magic, and enables the learning of the stabilizer group of an MPS. We showcase the efficacy and versatility of our method in the ground states of Ising and XXZ spin chains, as well as in circuits dynamics that has recently been realized in Rydberg atom arrays, where we provide concrete benchmarks for future experiments on logical qubits up to twice the sizes already realized.

Dairy subcomplex of Kazakhstan: condition, measures to improve efficiency

The current state of production of milk and its processed products in the regions of Kazakhstan has been studied. The goal is to assess the situation on dairy market, identify problems hindering the development of the industry, and develop recommendations to increase its competitiveness. Methods – monographic, logical, systemic and complex analysis, statistical data processing, constructive-functional approach. The works of domestic and foreign economists concerning the problems of dairy cattle breeding and milk processing structures were used as theoretical and methodological basis for scientific research. Results - factors directly influencing the growth of dairy product volumes were analyzed, including their quality, profitability, operation of logistics systems (supply chain, product transportation, transportation optimization), and marketing strategies. The method of economic and mathematical modeling was used to determine the strengths and weaknesses of enterprises, as well as the opportunities and threats of the external environment. Particular attention is paid to aspects of regulation of legislative framework, as well as adaptation to changing market conditions and consumer preferences. To increase production of own high-quality milk and reduce import dependence, the state actively supports and stimulates the creation of dairy farms, increases the volume of state subsidies for agricultural producers, and simplifies lending and micro lending system. It is important to ensure increase in profitability of dairy producers, reduce the influence of seasonality on price situation of dairy market, and develop infrastructure of social nutrition system. Conclusions - it is necessary to introduce new technologies, digital transformation in livestock farming, increase in technical equipment, allowing to increase the size of gross product, level of self-sufficiency in domestic products and expand participation in foreign trade as the main form of international economic relations.

A quantum secure multi-party summation protocol with quantum Fourier transform

In this paper, a quantum secure multi-party summation scheme with a third party based on quantum Fourier transform (QFT) is put forward, where the third party cannot be permitted to cooperate with others but is allowed for all kinds of attacks. Under the help of third party, [Formula: see text] users can calculate the addition modulo [Formula: see text] of their private integer strings. The third party generates two-level single qubit and its product state as the initial quantum resource, produces the traveling particles with QFT and the controlled-not (CNOT) operations, and sends the traveling particles out to the first users; then, [Formula: see text] users encode their private integer sequences by performing the phase shifting operations on the travelling particles one after another; and finally, the third party decodes out the summation of the private integer sequences from [Formula: see text] users through CNOT operations and inverse quantum Fourier transform (IQFT). This protocol only adopts two-level single particle state and its product state as initial quantum resource, only needs [Formula: see text]-level single particle measurement and does not need to perform quantum entanglement swapping. Security analysis indicates that this protocol can overcome not only the outside attack but also the participant attack.

A new quantum secure multiparty summation protocol with locally indistinguishable orthogonal product states

As an important branch of quantum-secure multiparty computation, quantum-secure multiparty summation enables participants to complete the summation of their inputs without revealing their own secrets. In this paper, a new multiparty quantum secure summation protocol based on locally indistinguishable orthogonal product (LIOP) states is proposed. Leveraging the properties of LIOP states, participants can successfully accomplish the summation of their secrets with the assistance of a semi-honest third party (TP). The present protocol is shown to effectively resist certain existing attacks. Furthermore, complex operations and entanglement resources are not required in the proposed protocol. We anticipate that these results will contribute positively to the future development of quantum-secure multiparty computation.

Investigación sobre calidad en educación superior en Chile: un estudio bibliométrico

The concept of quality in higher education is broad and complex. Achieving quality education is the foundation for sustainable development. One of the most commonly used standards for its evaluation are research activities on the subject. Bibliometric studies contribute to this by highlighting trends or underexplored aspects. Few studies analyze the state of scientific production on the quality of higher education in Chile. This study aims to describe the scientific output related to the quality of higher education in Chile. A longitudinal descriptive bibliometric analysis on 154 publications collected from Google Scholar between the years 2002 and 2021 was conducted. The results were the following: 1) The number of publications has increased over time; 2) Most of the publications are research studies; 3) The majority of publications in this field is mainly produced by a few authors affiliated with certain national university institutions; 4) Most of the publications focus on institutional aspects of quality management in higher education. It is concluded that the topic is relevant, with concentrated production oriented towards policies on the quality of higher education.

Planning of multi-production line maintenance

Efficiency of production lines is significantly impacted by maintenance activities, which are often overshadowed by the focus on production planning. The symbiotic relationship between maintenance and production activities is a critical yet overlooked factor. We examine the importance of maintenance planning, specifically within the dynamic context of production line operations. In this maintenance planning setting, scarce resources, particularly technicians, are commonly disregarded. Our research addresses the challenge of real-time maintenance planning across multiple production lines by developing a state-of-the-art heuristic, which takes into account machine production states and resource availability and is augmented by re-enactment procedures. We validate the heuristic by employing Markov Decision Processes and digital twin Discrete Event Simulations, which leverage real-world production data. This modeling framework is new for this specific problem. In our experiments, we compare the heuristic against optimal policies and practitioner-based policies. Our heuristic matches the performance of optimal policies in the Markov Decision Processes and significantly outperforms FCFS and practitioner-based policies in the Discrete Event Simulations. Notably, our heuristic is not only effective against standard policies, realizing improvement of 1% to 3%, but it is also the first to be generally applicable to production lines involving multiple machines and resources in real-time.

Combining matrix product states and noisy quantum computers for quantum simulation

Combining matrix product states and noisy quantum computers for quantum simulation

Explicit n-particle harmonic oscillator states in products of SU(1,1) representations

In this paper, we present a simple algorithm for the explicit construction of [Formula: see text]-particle harmonic oscillator states simultaneously belonging to irreducible representations of [Formula: see text] (or [Formula: see text]) and [Formula: see text]. For degenerate representations, the construction can be done using generating functions or hyperspherical harmonics. The cases with [Formula: see text] and [Formula: see text] are investigated at greater length. The analysis is extended to nondegenerate states, although the states are not so easily obtained as in the degenerate case. Finally, we briefly touch on the [Formula: see text] structure of Bell states.