Search Results (1,930)

The assessment of energy savings is not a trivial matter, as we have direct meters for consumption, but not for the absence of consumption. Calculating a simple difference between consumption before and after the implementation of an energy saving measure is also an incomplete assessment. The only way to determine energy savings is to compare the consumption that would have occurred in the absence of the saving measure with the actual consumption, with reference to the same external conditions and the same period. This is what the international IPMVP^® protocol establishes. This study, based on two case studies of industrial energy saving measures, explores the aspects of the calculation related to decarbonization and economic evaluation. In particular, sensitivity analyses of energy and economic indicators are carried out based on factors that evolve over time, such as the rate of inflation and discounting of investments and the variation in the carbon dioxide emission factor for electricity production. The main results highlight that the assumption of a constant electricity emission factor leads to an overestimation of the total CO₂ savings from energy efficiency interventions that can be more than 40%. The uniqueness of this paper is the application of a standardized savings evaluation procedure (IPMVP^®) in order to analyze the sensitivity of economic savings towards some key financial parameters, and the specific fitting of an electricity emission model to the Italian power sector in order to correct the carbon savings evaluation to the projected emission factor evolution. Full article

Dynamical friction implies a consistency check on any system where dark matter particles are hypothesised to explain orbital dynamics requiring more mass under Newtonian gravity than is directly detectable. Introducing the assumption of a dominant dark matter halo will also imply a decay timescale for the orbits in question. A self-consistency constraint hence arises, such that the resulting orbital decay timescales must be longer than the lifetimes of the systems in question. While such constraints are often trivially passed, the combined dependencies of dynamical friction timescales on the mass and orbital radius of the orbital tracer and on the density and velocity dispersion of the assumed dark matter particles leads to the existence of a number of astronomical systems where such a consistency test is failed. Here, we review cases from stars in ultrafaint dwarf galaxies, galactic bars, satellite galaxies, and, particularly, the multi-period mutual orbits of the Magellanic Clouds, as recently inferred from the star formation histories of these two galaxies, as well as the nearby M81 group of galaxies, where introducing enough dark matter to explain observed kinematics leads to dynamical friction orbital decay timescales shorter than the lifetimes of the systems in question. Taken together, these observations exclude dark matter halos made of particles as plausible explanations for the observed kinematics of these systems. Full article

The construction of self-dual and linear complementary dual (LCD) codes over finite rings, particularly over semi-local and local structures, is an active area of research due to their algebraic richness and applications in communications and cryptography. In this paper, we investigate double circulant and double negacirculant codes over the local ring $R_{q,u,v}={\mathbb{F}}_q+u{\mathbb{F}}_q+v{\mathbb{F}}_q,u^2=v^2=uv=vu=0,$ where $q=p^m$ is an odd prime power. Unlike the semi-local case, where decomposition via non-trivial idempotents simplifies analysis, the local structure of $R_{q,u,v}$ (with only trivial idempotents) makes enumeration and classification significantly more challenging. We first establish necessary and sufficient conditions for such codes to be self-dual or LCD; we then count the solutions to key equations over ${\mathbb{F}}_q$, including $a{b}^q+b{a}^q=0,$ to enable their enumeration. We further show that Gray images preserve these properties, leading to good self-dual and LCD codes over ${\mathbb{F}}_q$, and present optimal examples over ${\mathbb{F}}_7$. Our results extend double circulant constructions to a new algebraic setting, providing both theoretical advancements and practically relevant code designs. Full article

Over the last decade, Software-Defined Networking (SDN) has garnered increasing research interest for networking and security. This interest stems from the programmability and dynamicity offered by SDN, as well as the growing importance of SDN as a foundational technology of future telecommunications networks and the greater Internet. However, research into SDN security has focused disproportionately on the security of the control plane, resulting in the relative trivialization of data plane security methods and a corresponding lack of appreciation of the data plane in SDN security discourse. To remedy this, this paper provides a comprehensive review of SDN data plane security research, classified into three primary research domains and several sub-domains. The three primary research domains are as follows: security capabilities within the data plane, security of the SDN infrastructure, and dynamic routing within the data plane. Our work resulted in the identification of specific strengths and weaknesses in existing research, as well as promising future directions, based on novelty and overlap with emerging technology domains. The most striking future directions are the use of hybrid SDN architectures leveraging a programmable data plane, SDN for heterogeneous network security, and the development of trust-based methods for SDN management and security, including trust-based routing. Full article

The distributivity of implications over fuzzy operators is a desirable property for fuzzy systems and can be employed in the elimination of the explosion of if–then rules. In this paper, we try to explore the relationship between the distributivity over the uninorms-related fuzzy connectives and the distributivity over uninorms in the threshold generation method, i.e., the distributive equations $I(u,U_1(v,w))=U_2(I(u,v),I(u,w))$ and $I(U_1(u,v),w))=U_2(I(u,w),I(v,w))$ with I being the threshold-generated implication. Consequently, we find that if the uninorms are restricted to special classes, then the distributivity property by the first equation can be preserved between the original and threshold-generated implications; under certain constraints on the threshold-generated implication, the distributivity property by the second equation becomes trivial. Full article

This paper provides a complete classification of four-dimensional complex Poisson algebras, extending previous work on lower-dimensional cases. We develop a systematic approach that combines the classification of four-dimensional complex commutative associative algebras with the classification of four-dimensional complex Lie algebras, allowing us to determine all compatible Poisson structures up to isomorphism. Our main result presents 71 distinct types: 60 isolated non-isomorphic Poisson algebras with non-trivial commutative product and 11 one-parameter families of non-isomorphic Poisson algebras. In addition to these, we include the known four-dimensional complex Lie algebras, viewed as Poisson algebras with trivial commutative product. This purely algebraic classification provides a foundation for future studies, including the geometric classification of Poisson algebras, their degenerations, and the analysis of orbit closures in the corresponding algebraic variety. Full article

We theoretically investigate the stability of double-Q square skyrmion crystals under uniaxial distortion. Using an effective spin model with frustrated exchange interactions and bond-dependent anisotropy in momentum space, we construct the low-temperature magnetic phase diagram via simulated annealing. Our results reveal that uniaxial distortion drives a phase transition from the skyrmion crystal to a single-Q conical spiral state when the ratio of exchange interactions parallel and perpendicular to the uniaxial axis is reduced to about 95%. We further find that topologically trivial double-Q states, which emerge in the low- and high-field regimes, are more robust against uniaxial distortion than the skyrmion crystal appearing in the intermediate-field regime. Finally, we examine the role of bond-dependent anisotropy and demonstrate that a finite relative magnitude of this anisotropy is crucial for stabilizing the skyrmion crystal, even under uniaxial distortion. These findings highlight the delicate interplay between lattice distortions and bond-dependent interactions in determining the stability of multiple-Q magnetic textures, and they provide useful guidance for experimental efforts to manipulate skyrmion crystal phases in centrosymmetric magnets. Full article

Background: Studies assessing poor postoperative recovery using patient-centered metrics among older adults are scarce. We aimed to explore poor postoperative recovery in octogenarians and nonagenarians, characterized using the validated patient-centered tool ‘days alive and out of hospital’ (DAOH). Methods: This retrospective cohort study included patients aged ≥ 80 years who had non-palliative surgery at a tertiary academic center between January 2017 and July 2021. We explored the incidence of DAOH at 90 days (DAOH₉₀) ≤ 45 days as a pragmatic patient-centered marker of poor postoperative recovery. We also identified independent risk factors associated with this outcome using logistic regression models. Sensitivity analyses were performed using similar regression models. Results: Among 3683 included patients (median age 84 years), 640 patients (17%) had poor postoperative recovery. Of them, 240 patients (38%) survived the 90-day postoperative period but suffered a cumulative hospitalization period of over 45 days, and 400 patients (62%) died during the 90-day postoperative period. The most significant risk factors were ASA physical status classification (adjusted odds ratio (aOR) 3.52 [95% CI 2.55–4.87] for class 3E-5E compared to class 1–2), renal failure (aOR 3.49 [2.01–6.06] for GFR < 15 compared to GFR > 60 mL/min/1.73 m²), and high-risk surgery (aOR 1.85 [1.47–2.32]). Conclusions: We found a non-trivial rate of poor postoperative recovery in octogenarians and nonagenarians. DAOH₉₀ ≤ 45 days is a simple, clear, and intuitive tool that may enhance patient-centered research and promote communication about expected outcomes, support shared decision making, and provide personalized risk assessment aligned with older patients’ goals of care. Full article

In this paper, we propose a novel low-power implementation of the radix-2² Fast Fourier Transform (FFT) processor that exploits optimized multiplications and low-voltage memory buffers. The FFT computation requires complex products between input samples and precomputed coefficients, known as twiddle factors, as well as a large number of memory elements to store intermediate signals. To reduce power consumption, we bypass multiplications when twiddle factors are equal to zero or one. Furthermore, we introduce a fixed-width technique that lowers multiplier complexity for non-trivial coefficients by pruning the least significant columns of the partial product matrix and discarding the most significant partial products with low activation probability. To further minimize power consumption, we lower the supply voltage of memory buffers, creating two power domains in the design. Post-synthesis analysis in 28 nm technology shows that the proposed FFT achieves superior SNR and MSE compared to existing implementations, with reductions of 33% in power consumption and 30% in the power-delay product. In an OFDM receiver, the design also achieves optimal bit error rate performance under various levels of channel noise. Full article

Polar patterns and topological defects are ubiquitous in active matter. In this paper, we study a paradigmatic polar active dumbbell system through numerical simulations, to clarify how polar patterns and defects emerge and shape evolution. We focus on the interplay between these patterns and morphology, domain growth, irreversibility, and compressibility, tuned by dumbbell rigidity and interaction strength. Our results show that, when separated through MIPS, dumbbells with softer interactions can slide one relative to each other and compress more easily, producing blurred hexatic patterns, polarization patterns extended across entire hexatically varied domains, and stronger compression effects. Analysis of isolated domains reveals the consistent presence of inward-pointing topological defects that drive cluster compression and generate non-trivial density profiles, whose magnitude and extension are ruled by the rigidity of the pairwise potential. Investigation of entropy production reveals instead that clusters hosting an aster/spiral defect are characterized by a flat/increasing entropy profile mirroring the underlying polarization structure, thus suggesting an alternative avenue to distinguish topological defects on thermodynamical grounds. Overall, our study highlights how interaction strength and defect–compression interplay affect cluster evolution in particle-based active models, and also provides connections with recent studies of continuum polar active field models. Full article

Industrial processes governed by food safety regulations, such as high-temperature short-time (HTST) pasteurization, rely on continuous sensor monitoring to ensure compliance with standards like Hazard Analysis and Critical Control Points (HACCP). However, extracting actionable process insights from raw sensor data remains a non-trivial task, largely due to the continuous, multivariate, and often high-frequency characteristics of the signals, which can obscure clear activity boundaries and introduce significant variability in temporal patterns. This paper proposes a process mining framework to extract activity-based representations from multivariate sensor data in a pasteurization scenario. By modelling temperature, pH, conductivity, viscosity, turbidity, flow, and pressure signals, the approach segments continuous data into discrete operational phases and generates event logs aligned with domain semantics. Unsupervised learning techniques, including Hidden Markov Models (HMMs), are used to infer latent process stages, while domain knowledge guides their interpretation in accordance with critical control points (CCPs). The extracted models support conformance checking against HACCP-based procedures and enable predictive process-monitoring tasks such as next-activity prediction and remaining time estimation. Experimental results on synthetic (literature-grounded data) demonstrated the method’s ability to enhance safety, compliance, and operational efficiency. This study illustrates how integrating process mining with regulatory principles can bridge the gap between continuous sensor streams and structured process analysis in food manufacturing. Full article

The paper investigates disparities in food waste generation across European Union countries between 2020 and 2022, focusing on spatial and sustainability dimensions. It utilizes data for six key food waste parameters and a broad range of environmental, social and economic indicators. A combination of statistical methods, including correlation analysis, cluster analysis and Principal Component Analysis, uncovers multivariate patterns and identifies groups of countries with similar food waste characteristics and related factors. The paper highlights the temporal and spatial dynamics of food waste over the three-year period, particularly in light of the COVID-19 pandemic. While the total volume of food waste remained relatively stable across the EU, notable shifts occurred in waste sources. Household food waste peaked in 2021, likely due to increased time spent at home during pandemic-related lockdowns. Conversely, waste from retail, restaurants and food service sectors showed a consistent increase. The paper identifies non-trivial correlations between food waste and socio-economic variables, suggesting that differences in food waste generation across EU countries are influenced by a complex interplay of factors, including policy effectiveness, cultural practices, consumer behaviour and economic conditions. This comprehensive analysis of food waste patterns across EU countries and over time offers valuable insights for policymakers aiming to reduce waste and promote sustainability. Full article

Mesenchymal stem cells are widely cultivated in stirred tank bioreactors. Due to their adhesion properties, they are attached to small spherical spheres called microcarriers. To understand the hydromechanical stresses encountered by the cells, it is essential to characterize the flow using the PIV technique. However, the usual solid–liquid system used in cell cultures has poor optical properties. Thus, shifting to one with better optical properties, while respecting the physical characteristics, is mandatory to achieve a relevant representation. PMMA microparticles suspended with 61 wt% ammonium thiocyanate solution NH₄SCN were found to be a robust candidate. The refractive index (RI) of both sides is of the order of 1.491 with a density ratio of ${\rho }_f/{\rho }_p\approx$ 0.96, and particle size averaged around 168 μm. Using the RIM-PIV (refractive index matched particle image velocimetry) technique for a 0.7 L volume stirred tank equipped with an HTPG down-pumping axial impeller and operating at full homogeneous speed $N=150$ rpm, mean and turbulence quantities of the liquid phase were measured as a function of PMMA particle volume fractions ${\alpha }_p$, which ranged from 0.5 to 3 v%. This corresponds to a particle number density of $n=12$ particles/mm³, which is considered original and challenging for the PIV technique. At 3 v%, the addition of particles dampened the turbulent kinetic energy (TKE) of the liquid phase locally by 20% near the impeller. This impact became trivial (<10%) at the local-average level. The structure and direction of the recirculation loop also shifted. Full article

Adequate intake of fruits and vegetables (F + V) supports healthy growth and development in children, yet many New Zealand children do not meet national dietary recommendations, and methods to evaluate intake require good reliability. Objectives: To establish the validity and reliability of a modified 24 h multiple pass recall (MPR) for evaluating F + V and carotenoid intakes in children aged 9–13 years. The reliability of the Veggie Meter^® (VM^®), a non-invasive reflection spectrometer to estimate skin carotenoid scores and derive blood carotenoid concentrations, was also examined. Methods: Thirty-two children (20 boys, 12 girls) completed three 24 h MPRs and parent-assisted weighed food diaries (WFDs) on randomised weekdays and weekends. Skin carotenoid scores were assessed using the VM^®. The validity of the MPR was evaluated against WFDs using log-transformed Pearson correlations and mean x-axis bias. The reliability was assessed by the coefficient of variation (CV) and Pearson correlations. Results: Participants did not meet recommended F + V intakes (5–5.5 servings/day): MPR (mean fruit 1.3 servings/day; vegetables 2.0), WFD (fruit 1.3; vegetables 1.9). The MPR was a valid tool to estimate fruit and vegetable daily servings (combined-day Pearson coefficients > 0.71) with only trivial–small standardized mean bias-offset vs. WFD; however, the reliability was poor for the MPR-estimated carotenoid intake (CV 126%) and F + V intake. In contrast, the VM^® was reliable (Pearson correlation 0.97–0.99) with low measurement error (CV 4.0–5.2%). Conclusions: The modified 24 h MPR was valid but unreliable for estimating F + V and carotenoid intake. The VM^® demonstrated high reliability as a biomarker of skin carotenoid status in children. Full article

Kaniadakis deformed $\kappa$-mathematics is an area of mathematics that has found relevance in the analysis of complex systems. Specifically, the mathematical framework in the context of a first-order decay $\kappa$-differential equation is investigated, facilitating an in-depth examination of the $\kappa$-mathematical structure. This framework serves as a foundational platform, representing the simplest non-trivial setting for such inquiries which are demonstrated for the first time in the literature. Finally, additional avenues of study are discussed. Full article