Search Results (12)

One of the negative effects of the rapid increase in the number and capacity of photovoltaic power sources distributed in consumption areas by connecting to existing low-, medium-, and high-voltage distribution networks is the increased risk of amplifying the non-sinusoidal steady-state condition caused by high-power inverters. This amplification occurs if the peak values of harmonic impedance in the sections of the respective grid zone, which depend on the values of the equivalent shunt capacitances present in the grid, correspond to frequency values that coincide with or are close to the frequencies of the harmonic currents injected by the distributed sources. The risk is particularly high in cases of malfunction or failure of the filters within the installations associated with these sources. High shunt capacitance values are not only caused by the capacitive compensators used to increase the power factor of consumers or to improve the voltage level in the grid, but also by long power lines, particularly long underground lines. Risks increase as the proportion of underground power lines in the network area with sources of harmonic currents rises. This article refers to a real high-voltage grid area where the distribution operator plans to install high-power photovoltaic sources, the connection of which requires grid expansion through the construction of new substations and high-voltage power lines (110 kV). Based on the designer’s intention for the new high-voltage power lines to be underground and of relatively long lengths—which implies the presence of high natural capacitances—the authors conduct two case studies to predictively evaluate the harmonic impedance in the network sections resulting from the expansion, with the aim of identifying the frequencies at which parallel resonances may occur. The authors use two software tools for numerical analysis, Mathcad 14.0 and MATLAB–Simulink 2025A, and compare the results obtained for two design variants of the new high-voltage lines: overhead and underground, respectively. Using the mathematical model of long lines in steady state with uniformly distributed parameters, the analysis highlights that the highest values of harmonic impedance correspond to the overhead line design variant. The use of this design variant increases the risk of parallel resonances, not only by increasing the harmonic impedance values but also by widening the frequency ranges for which the impedance has high values. In both the overhead line and underground line variants, increasing the load leads to a reduction in the maximum values. Compared to the design variant using overhead lines, the variant with underground lines increases the risk of parallel resonances by increasing the number of frequency intervals for which the harmonic impedance has high values, but this increase is limited by narrowing these frequency intervals and reducing the harmonic impedance values. An important contribution of the article lies in arguing the need to extend the conventional node-based evaluation of harmonic impedance by treating harmonic impedance as a continuous spatial frequency characteristic of the transmission network. The impedances seen at nodes become the impedances seen in particular sections/sections of the network, identified by the value of the variable that specifies their position in space, more precisely the distance from the end of one of the feeders on which they are located. Full article

The Crab pulsar produces extremely intense, short-duration radio bursts known as giant pulses (GPs). We introduce a cumulative-energy diagnostic to quantify the apparent spectral extent of individual Crab giant pulses across the ultra-wideband low-frequency (UWL) receiver band, aiming to build a reproducible method for describing the frequency-domain concentration of emission and to characterize the observed spectral diversity of Crab GPs. Using UWL receiver on the Murriyang (Parkes) radio telescope, we present a systematic study of GPs from the Crab pulsar (PSR J0534+2200). We introduce an empirical classification scheme based on the cumulative distribution function of the pulse energy as a function of observing frequency. We use this diagnostic to separate events with apparent spectral concentration from events with broader spectral coverage. Under this empirical classification scheme, most detected events show apparent spectral concentration within a limited frequency range. Events classified as apparently spectrally concentrated contain most of their measured relative energy within limited frequency ranges, whereas broadband events show more extended spectral coverage. We emphasize that this classification describes the observed spectral extent and should not by itself be interpreted as proof of intrinsically narrow-band emission. Spectral fitting shows that most apparently spectrally concentrated (ASC) GPs have negative spectral indices, while a few events exhibit positive slopes, indicating substantial spectral diversity within the sample. The 3$\sigma$ widths of ASC main pulse GPs appear to cluster around two characteristic ranges, although this feature should be interpreted with caution given the finite time resolution of the data. The energy distribution of ASC main pulse GPs is broadly consistent with a log-normal functional form at low-to-intermediate energies and resembles a power-law-like tail at the high-energy end. The waiting-time distribution can be described by a Weibull function, while a sliding-window comparison with Monte Carlo realizations of a Poisson distribution shows no statistically significant deviation from temporal independence over the present 18.9-min observing span. The CDF-based classification method developed here is transferable to other wideband receiver data, provided that careful consideration is given to the instrumental bandpass, frequency-dependent sensitivity, RFI masking, and signal-to-noise thresholds. These results provide observational constraints on the phenomenology of Crab GPs and may be useful for future studies of pulsar coherent emission and related radio transients. Full article

We prove a complete moment convergence criterion for weighted maximal partial sums of extended negatively dependent (END) random variables under slowly varying weights. For every $r>1$, and for triangular weight arrays that are uniformly bounded, quadratically non-degenerate, and uniformly non-degenerate on their active coefficients, we show that the summability of $n^{r-1}l\left(n\right)E\left[{(S_n^{*}/n-\epsilon )}_{+}\right]$ for all $\epsilon >0$ is equivalent to the weighted moment condition ${E\left[\right|X|}^{r+1}l\left(\right|X\left|\right)]<\infty$. The slowly varying factor l gives a refined borderline scale: it weakens the pure $(r+1)$-moment condition when $l\left(t\right)\to 0$, strengthens it when $l\left(t\right)\to \infty$, and recovers the classical scale when l is bounded away from zero and infinity. The proof uses weight-dependent monotone clipping, a Rosenthal-type maximal inequality for END sequences, Potter bounds and Karamata-type estimates for slowly varying functions, and a Bonferroni lower-bound argument based on a linear set of significant coefficients. Particular attention is paid to the preservation of the END structure under clipping, centering, and signed weights. Several corollaries and borderline heavy-tail examples are included, and possible modeling interpretations are briefly discussed without claiming finite-sample risk bounds beyond the theorem. Full article

Extended droughts are predicted for southwestern North America, including the arid Mojave Desert, which has plant communities dominated by desert scrub vegetation. We conducted a multi-year study in which supplemental water was provided to four native shrub species: the evergreen Larrea tridentata and deciduous Ambrosia dumosa, Ambrosia salsola, and Encelia farinosa. Water treatments included −25% of precipitation (by temporarily deploying large tarps over wooden support structures), actual precipitation, and 100% and 200% of actual precipitation. Water applied occurred within 24 h of actual precipitation events. At the end of a two-year period, we allowed the plots to remain intact, receiving no supplemental water for 3.8 years, which was anomalously dry. During the initial two-year experiment, we examined growth and other physiological responses to the treatments. We also measured soil volumetric water content with depth and calculated a plant water stress index. After the 3.8-year dry period we measured stem elongation, canopy volume, leaf xylem water potential and harvested roots and shoots for biomass estimates. Supplemental water led to higher soil water content and water use, leading to increased aspects of growth which were species dependent, whereas the −25% treatment resulted in greater stress and reduced growth, but only in some species. After the 3.8-year dry period, survival in all treatments was between 97 and 100%. However, a distinct legacy effect was observed, as plants growing under the wetter treatments during the 2-year supplemental water period had more negative leaf xylem water potentials after the 3.8-year dry period than plants that were grown under the drier treatments. In addition, canopy volumes were shown to decrease if plants were grown under the wetter treatment imposed during the supplemental water period but increased if grown under the drier treatments. Our results would suggest that the impact of climate change on Mojave Desert shrubs will be linked to how they respond to wet/dry cycles, which will be linked to drought severity and the time between wet periods. The four shrub species studied have unique morphological and physiological characteristics that allow them to grow and not just survive under arid conditions, but if extended drought events occur on a more frequent basis, these shrub species may not be able to adapt and thus avoid higher mortality rates. Full article

This model extends the classical economic production quantity (EPQ) model to address the complexities within a two-echelon supply chain system. The model integrates the cost of raw materials necessary for production and takes into account the presence of imperfect quality items within the acquired raw materials. Upon receipt of the raw material, a thorough screening process is conducted to identify imperfect quality items. Combining imperfect raw material and the concept of shifting production rate, two different inventory models for deteriorating products are formulated under imperfect production with demand dependent on the stock level. In the first model, the imperfect raw materials are sold at a discounted price at the end of the screening period, whereas in the second one, imperfect items are kept in stock until the end of the inventory cycle and then returned to the supplier. Numerical analysis reveals that selling imperfect raw materials yields a favourable financial outcome, with an optimal inventory level $I_1$ = 11,774 units, optimal cycle time $T=2140$ h, and a total profit per hour of USD 183, while keeping the imperfect raw materials to return them to the supplier results in a negative profit of USD $-4.44\times {10}^3$ per hour, indicating an unfavourable financial outcome with the optimal inventory level $I_1$ and optimal cycle time T of 26,349 units and 4702.6 h, respectively. The findings show the importance of selling imperfect raw materials rather than returning them and provide valuable insights for inventory management in systems with deteriorating products and imperfect production processes. Sensitivity analysis further demonstrates the robustness of the model. This study contributes to satisfying the need for inventory models that consider both the procurement of imperfect raw materials, stock-dependent demand, and deteriorating products, along with shifts in production rates in a multi-echelon supply chain. Full article

With the rapid development of the semiconductor industry, the demand for high-speed testing in the large-scale production of semiconductor devices and integrated circuit production lines continues to grow. As one of the key tools in semiconductor device performance testing and integrated circuit testing, source measure unit (SMU) plays a crucial role in high-precision transient response testing scenarios. In high-precision measurement scenarios, multiple measurements are often required and averaged to improve measurement accuracy, but this can slow down the measurement speed. This article proposes a measurement acceleration algorithm based on BA-Informer time series prediction to solve the problem of decreased measurement speed in high-precision measurement. On the one hand, this algorithm improves the encoder structure. Traditional time series prediction models may have limitations in handling long-term dependencies and trend extraction. BiRNN is an extended version of recurrent neural network (RNN), which consists of two directional RNN. One forward RNN processes data from the beginning to the end of the sequence, while the other reverse RNN processes data from the end to the beginning of the sequence. In the end, the outputs from both directions are merged at each time step. Compared to traditional one-way RNN, BiRNN can more effectively handle data with before and after dependencies. Based on its characteristics, this article integrates BiRNN into the encoder structure. This algorithm can simultaneously process input sequences from both positive and negative directions, effectively limiting the bidirectional contextual information of data and significantly enhancing the model’s ability to capture time series trends. In this paper, BiRNN is integrated into the encoder structure, and the algorithm can simultaneously process input sequences from both positive and negative directions, more effectively capturing the bidirectional contextual information of data and significantly enhancing the model’s ability to capture time series trends. This improvement enables the model to more accurately grasp the overall trend of data changes during prediction, thereby improving prediction accuracy. On the other hand, an attention discrete cosine transform (ADCT) module is introduced between the encoder and decoder to convert time-domain signals into frequency-domain representations. This not only reveals the spectral characteristics of the signal but also reduces data redundancy and improves the efficiency of subsequent processing by combining attention mechanisms. Finally, the algorithm performance is analyzed by analyzing the output characteristic curves of loads with different properties. The experiment shows that the prediction algorithm and the combination of measurement and prediction method proposed in this article save half of the measurement time by combining measurement and prediction while ensuring the same amount of data obtained, verifying the effectiveness of the proposed method. Full article

This paper introduces an innovative concentration inequality for Extended Negative Dependence (END) random variables, providing new insights into their almost complete convergence. We apply this inequality to analyze END variable sequences, particularly focusing on the first-order auto-regressive (AR(1)) model. This application highlights the dynamics and convergence properties of END variables, expanding the analytical tools available for their study. Our findings contribute to both the theoretical understanding and practical applications of END variables in fields such as finance and machine learning, where understanding variable dependencies is crucial. Full article

Despite the fact that peptide conjugates with a pendant ferrocenyl (Fc) have been widely investigated, bis-ferrocenyl end-capped peptides are rarely synthetized. In this paper, in addition to the full characterization of the Fc-CO-[_L-Dap(Boc)]_n-NH-Fc series, we report a comparison of the three series of bis-ferrocenyl homopeptides synthesized to date, to gain insights into the influence of α-amino isobutyric (Aib), 2,3-diamino propionic (Dap) and C^α,β-didehydroalanine (ΔAla) amino acids on the peptide secondary structure and on the ferrocene redox properties. The results obtained by 2D NMR analysis and X-ray crystal structures, and further supported by electrochemical data, evidence different behaviors depending on the nature of the amino acid; that is, the formation of 3₁₀-helices or fully extended (2.0₅-helix) structures. In these foldamers, the orientation of the carbonyl groups in the peptide helix yields a macrodipole with the positive pole on the N-terminal amino acid and the negative pole on the C-terminal amino acid, so that oxidation of the Fc moieties takes place more or less easily depending on the orientation of the macrodipole moment as the peptide chain grows. Conversely, the fully extended conformation adopted by ΔAla flat peptides neither generates a macrodipole nor affects Fc oxidation. The utilization as electrochemical and optical (Circular Dichroism) probes of the two terminal Fc groups, bound to the same peptide chain, makes it possible to study the end-to-end effects of the positive charges produced by single and double oxidations, and to evidence the presence “exciton-coupled” CD among the two intramolecularly interacting Fc groups of the _L-Dap(Boc) series. Full article

Background: Although prior research on the housing–health linkage suggested that those with poor housing conditions are more likely to report poor health, it is dominated by Western studies and offers little evidence on the housing–health relation in China. Scarce is empirical evidence on the potentially detrimental impact of either qualitative or quantitative housing poverty on health outcomes, especially for seniors in China. This paper aims to fill this void by using data from the 2011–2015 China Health and Retirement Longitudinal Study (CHARLS) to provide a comprehensive analysis of the demographic, socioeconomic, and behavioral factors that contribute to changes in healthy aging among Chinese adults aged 60 and over. Methods: Data collected from 8839 adults aged 60 and over in the 2011 and 2015 CHARLS (3732 in 2011 and 5107 in 2015) were used. We first used six blood-based biomarkers to construct a composite measure of the Chinese Healthy Aging Index (CHAI, ranging from 0 (healthiest) to 12 (unhealthiest)) and then assessed the psychometric properties of the CHAI score, including acceptability, internal consistency, convergent validity, discriminative validity and precision. In addition, we employed both mean-based Blinder–Oaxaca and unconditional quantile regression decomposition to decompose the change in healthy aging within the 2011–2015 period. Results: We overall identified a decrease in CHAI score from 5.69 in 2011 to 5.20 in 2015, which implies an improvement in healthy aging during this period. Our linear decomposition revealed that dependent on the type of measure used (whether quality, quantity, or combined quality–quantity), housing poverty explained 4–8% of the differences in CHAI score. Our distributional decompositions also highlighted an important role for housing poverty in the change in healthy aging, accounting for approximately 7–23% of the explained portion. Within this latter, the relative contribution of housing quantity and quality poverty was more pronounced at the median and upper end of the CHAI distribution. We also found household expenditure to be significantly associated with healthy aging among older Chinese adults and made the largest contribution to the improvement in healthy aging over time. Conclusions: The association between housing poverty and CHAI is independent of household expenditure. Regardless of type, housing poverty is positively associated with a decrease in healthy aging. Thus, improved housing conditions boost healthy aging, and housing amelioration initiatives may offer the most effective solution for augmenting healthy aging in China. Improvement of flush toilets and the access to potable water and a separate kitchen require particular attention. Since high-density congested housing has a negative impact on healthy aging, more attention can also be paid to improvements in the available space for older people. Especially at an institutional level, the government may extend the housing policy from a homeownership scheme to a housing upgrading scheme by improving housing conditions. Full article

Kv1.2 channels, encoded by the KCNA2 gene, are localized in the central and peripheral nervous system, where they regulate neuronal excitability. Recently, heterozygous mutations in KCNA2 have been associated with a spectrum of symptoms extending from epileptic encephalopathy, intellectual disability, and cerebellar ataxia. Patients are treated with a combination of antiepileptic drugs and 4-aminopyridine (4-AP) has been recently trialed in specific cases. We identified a novel variant in KCNA2, E236K, in a Serbian proband with non-progressive congenital ataxia and early onset epilepsy, treated with sodium valproate. To ascertain the pathogenicity of E236K mutation and to verify its sensitivity to 4-AP, we transfected HEK 293 cells with Kv1.2 WT or E236K cDNAs and recorded potassium currents through the whole-cell patch-clamp. In silico analysis supported the electrophysiological data. E236K channels showed voltage-dependent activation shifted towards negative potentials and slower kinetics of deactivation and activation compared with Kv1.2 WT. Heteromeric Kv1.2 WT+E236K channels, resembling the condition of the heterozygous patient, confirmed a mixed gain- and loss-of-function (GoF/LoF) biophysical phenotype. 4-AP inhibited both Kv1.2 and E236K channels with similar potency. Homology modeling studies of mutant channels suggested a reduced interaction between the residue K236 in the S2 segment and the gating charges at S4. Overall, the biophysical phenotype of E236K channels correlates with the mild end of the clinical spectrum reported in patients with GoF/LoF defects. The response to 4-AP corroborates existing evidence that KCNA2-disorders could benefit from variant-tailored therapeutic approaches, based on functional studies. Full article

The structural Ricardian model has been used to examine the links between climate variables and staple food production in the literature. However, empirical extensions considering the cluster-correlated effects of climate change have been limited. This study aims to bridge this knowledge gap by extending the structural Ricardian model to accommodate for spatial clustering of the climate variables while examining their effects on staple food production. Based on nationally representative farm household data in Taiwan, the present study investigates the effect of climate conditions on both crop choice and the subsequent production of the three most important staple foods. The results suggest that seasonal temperature/precipitation variations are the major determinants of staple food production after controlling for farm households’ socio-economic characteristics. The impacts of seasonal climate variations are found to be location-dependent, which also vary significantly across the staple food commodities. Climate change impact assessment under four Representative Concentration Pathways (RCPs) scenarios indicates the detrimental effect of climate change on rice production during 2021–2100. Under RCP6.0, the adverse effect of climate change on rice production will reach the high of approximately $2900 in the last two decades of the century. There is a gradual increase in terms of the size of negative impact on vegetable production under RCP2.6 and RCP4.5. Under RCP6.0 and RCP8.5, the effects of climate change on vegetable production switch in signs during the entire time span. The impact of climate change on fruits is different from the other two staple foods. The simulated results suggest that, except for RCP8.5, the positive impact of climate change on the production of fruits will be around $210–$320 in 2021–2040; the effect will then increase to $640–$870 before the end of the century. Full article

Previously it was shown that application of probiotics stopped the acquisition of vancomycin-resistant Enterococcus faecium (VRE) by patients in an early rehabilitation ward. Once the application of probiotics ended, we examined whether acquisition of VRE reoccurred. Furthermore, we examined whether probiotics altered prevalence of vancomycin-susceptible E. faecium (VSE) and Gram-negative bacteria, which produce extended spectrum beta-lactamase (ESBL). Although probiotic application ceased in April 2018, VRE-colonized patients rarely presented on that ward until 2019. Probiotic treatment also resulted in a decreased number of patients with VSE and ESBL. While decreased incidence of VRE occurred immediately, decreased VSE and ESBL numbers occurred months later. A probiotic-mediated decrease of VSE and ESBL incidence cannot be explained when assuming bacterial transmission exclusively as a linear cause and effect event. The decrease is better understood by considering bacterial transmissions to be stochastic events, which depend on various driving forces similar to an electric current. We hypothesize that VRE, VSE and ESBL uptake by patients and by staff members mutually reinforced each other, leading staff members to form a bacterial reservoir, similar to a condenser that stores electrical energy. Probiotic treatment then inhibited regeneration of that store, resulting in a breakdown of the driving force. Full article