Search Results (2,635)

Contemporary physiotherapy requires technological tools to provide effective therapy to the increasing group of patients with neurological conditions, among others. This can be achieved with rehabilitation robots, which can also be exoskeletons—wearable devices that mobilize multiple joints with complex motions representing activities of daily living. To perform kinesiotherapy conveniently in home-like environments, the exoskeletons need to be relatively lightweight. The paper presents the methodology for decreasing the mass of the exoskeleton design with real-life data-driven simulations of motions, followed by multibody dynamics simulations, and finite element method (FEM) multistep optimization. The process includes sequential initial parametric optimization, topology optimization, and final parametric optimization. The steps are used to set initial dimensional and material parameters, extract new geometrical features, and adjust the final geometry dimensions of a new design. The presented case of the SmartEx-Home exoskeleton resulted in a total mass reduction of almost 50% for the main construction elements while meeting the criteria of the minimum safety factor and maximum internal stress and strain for all components. The final design was manufactured and tested with humans, reflecting an almost fully automatic passive and active therapy. Full article

Urban flood resilience has emerged as a holistic citywide approach for mitigating flood hazards and navigating the impacts of extreme weather patterns induced by climate change. This is particularly pertinent for high-risk, low-elevation coastal cities like Georgetown, Guyana. However, while the literature on Georgetown includes assessments, analyses, modeling, vulnerability, and the socio-political history of flooding, we found no evidence of flood resilience assessment for the city. Therefore, this study presents a data-driven evaluation of flood resilience at the sub-district level in Georgetown. To accomplish this, we constructed flood resilience indices (FRIs) using the aggregated weighted mean index approach and census-based indicators across physical, social, and economic dimensions. Principal component analysis (PCA) was employed to generate these weights and, subsequently, to perform dimensionality reduction and determine a linear regression model for the FRI values. To evaluate the stability of the constructed indices, robustness tests were conducted using alternative normalization and weighting schemes to demonstrate the consistency of resilience rankings across specifications. The results show that (a) economic resilience is lowest, (b) there is notable clustering and sharp disparities in the physical and social dimensions, and (c) the social dimension has the strongest correlation with the total FRI, which is generally heterogeneous. PCA-derived principal components explained 77.347% of the variation in the FRI values, enabling dimensionality reduction and three-dimensional graphical presentations. Our findings provide urban planners with insights into the distribution of flood resilience needs across the city. This study enables informed decision-making, serving as a pathway to achieve equitable resource allocation and build the city’s resilience. Full article

High-power ultrasound has been widely used to regulate the anti-digestibility of starch-based products, including the formation of resistant starch (RS-V) in amylopectin assemblies. This can contribute to the attenuation of postprandial hyperglycemia. However, the mechanisms by which high-power ultrasound modulates RS-V remain to be elucidated. Therefore, nano-scale Euryale ferox amylopectin (EFA) ternary assemblies were constructed under high-power ultrasound. All EFA assemblies exhibited ternary self-assembly peaks and V-type crystallinity. Combined chemometric analyses revealed that, with increasing ultrasound power, the rising self-assembly sites within B2 and C chains promoted the increase in self-assembly index but decreased semicrystalline lamellae thickness and structural fractal dimension. Consequently, a compact and ordered molecular cross-linking network was formed, contributing to increases in residual crystallinity, molecular weight, short-range order, and molecular density. This resulted in the shrinkage of digestion channel structures and optimization of the molecular gel network. As a result, the reduction in hydrolysis sites with increasing ultrasound power led to increased RS-V content (22.66–60.17%), causing a decline in the estimated glycemic index. The EFA–lauric acid–lactoglobulin assemblies prepared under 600 W ultrasound were the optimal composition and exhibited enhanced anti-digestibility relative to amylopectin assemblies derived from staple crops such as white waxy maize. The present investigation not only serves as a valuable supplement for studying the precise regulation mechanisms of nano-scale amylopectin RS-V, but also provides critical theoretical guidance for the development of foods aimed at preventing hyperglycemia. Full article

Platelet-rich gel (PRG) is a fibrin-based biobased biomaterial generated by activating platelet-rich plasma (PRP), yet its biological characterization has commonly relied on univariate measurements of isolated mediators. This study aimed to define the multivariate biological organization of PRG and related hemocomponents (PRP, chemically induced platelet lysate (CIPL), and plasma) in a canine model under single exposure to non-steroidal anti-inflammatory drugs (NSAIDs). In a randomized crossover design (n = 6 dogs), hemocomponents were produced at baseline (0 h) and 6 h after administration of carprofen or firocoxib. Platelet and white blood cell (WBC) counts, growth factors (platelet-derived growth factor-BB (PDGF-BB) and transforming growth factor beta-1 (TGF-β1)), and cytokines (tumor necrosis factor alpha (TNF-α), interleukin-1 beta, and interleukin-10) were integrated using linear mixed-effects modeling, principal component analysis (PCA), and hierarchical clustering. PRG was derived from a leukocyte-poor PRP precursor with moderate platelet enrichment (~1.6-fold vs. whole blood) and a marked WBC reduction (~8–9-fold). In mixed-effects modeling, hemocomponent type significantly influenced the PDGF-BB:TNF-α log-ratio, with PRG (estimate −1.12; 95% CI −1.34 to −0.90) and plasma (−2.06; 95% CI −2.28 to −1.84) lower than PRP, while CIPL did not differ. Time and NSAID effects were not supported. PCA identified two orthogonal axes explaining 61.3% of total variance (PC1 = 43.7%, PC2 = 18.6%), separating a platelet/trophic dimension (log(PDGF-BB), log(TGF-β1), platelet count, PDGF-BB:TNF-α log-ratio) from an inflammatory dimension (log(TNF-α), log(IL-1β)). Overall, hemocomponent composition emerged as the primary determinant of mediator organization, supporting the interpretation of PRG as a structured, biomaterial defined by coordinated mediator networks. Full article

Soil drought impact on irrigation areas is not merely a single reduction in crop yields, but rather a chain reaction that occurs from multiple dimensions including crop growth, water resource allocation, soil environment, operation of irrigation area projects, agricultural economy and ecosystems. The changing trend and mutation characteristics of soil drought are unclear in the People’s Victory Canal Irrigation District (PVCID). The Standardized Soil Moisture Index (SSMI) and the breaks for additive seasons and trend (BFAST) decomposition algorithm were adopted, combined with the eXtreme Gradient Boosting (XGBoost) model, to explore spatio-temporal evolution characteristics, driving factors and response to meteorological drought of soil drought. During the research period, the area percentage of SSMI showing a downward trend was 97.30%. The most severe soil drought occurred in 2019. In addition, the optimal trivariate combination is precipitation, evapotranspiration, and air temperature. This study has clarified the spatio-temporal evolution laws and driving mechanisms of soil drought in the PVCID, providing an important theoretical basis for the early warning, prevention and control of soil drought and the adaptive management of the ecosystem. Full article

In contemporary communication systems, digital images occupy an irreplaceable role; however, the privacy-related risks attendant to their prevalent application have grown increasingly salient. This paper presents an image encryption scheme integrating a novel two-dimensional Ackley-Sine chaotic map (2D-ASM) with dynamic DNA operations. First, a two-dimensional Ackley-Sine chaotic map, constructed based on the Ackley function and sine function, is designed and validated through a series of chaotic indicators. Results demonstrate that 2D-ASM exhibits superior chaotic properties compared to several existing state-of-the-art chaotic maps, with its maximum Lyapunov exponent (LE) exceeding 23, Permutation Entropy (PE) close to 1 in the full parameter range, and correlation dimension (CD) significantly higher than comparative chaotic systems. The proposed 2D-ASM-based image encryption scheme leverages the SHA-256 hash value of the plaintext image and four external keys to jointly generate the initial conditions and parameters of the 2D-ASM chaotic system, thereby ensuring a sufficiently large key space of 2²⁵⁶. Subsequently, chaotic sequences generated by 2D-ASM are employed to permute and diffuse the plaintext image, followed by dynamic DNA coding, operations, and decoding to obtain the encrypted image. Security analyses and comparisons with several existing representative algorithms confirm that the proposed encryption scheme achieves excellent encryption performance: the Number of Pixels Change Rate (NPCR) is above 99.6%, the Unified Average Changing Intensity (UACI) approaches 33.4%, and the information entropy of ciphertext images reaches 7.999 or higher. The scheme can effectively resist various potential attacks, including statistical and differential attacks, and outperforms representative algorithms in pixel correlation reduction and anti-interference performance. Full article

Addressing the dual challenges of efficient water resource utilization and high construction costs in agricultural production, this study proposes a low-cost sprinkler irrigation system featuring a joint optimized design of water supply facilities and sprinkler layout. Initially, to mitigate water wastage at the field boundaries, an enhanced sprinkler layout is designed. This design strategically adjusts sprinkler spacing to position units along the irrigation area’s perimeter, leveraging their adjustable spray angles for semicircular coverage, thereby achieving superior water conservation compared to traditional honeycomb full coverage layouts. Subsequently, considering the non-linear relationship between pipeline cost and its length and flow rate, a supply network comprising five independent pipelines running perpendicular to the river is constructed. Furthermore, water storage tanks are strategically located at the head of each pipeline near the water source to reduce costs. Finally, constrained by the daily soil moisture levels required for crop survival, an inference-based dimension reduction algorithm is employed to jointly optimize the daily pipeline flow rate and storage tank capacity for each supply line. Specifically, by constructing the functional mapping between flow rate and tank capacity, the complex bivariate optimization problem is reduced to a single-variable extremum problem. Additionally, a calculation method for the feasible region of decision variables is proposed to ensure solution validity. The results demonstrate that the proposed scheme achieves a minimum total construction cost of CNY 2,611,404.00 with a total storage tank capacity of 114,892.40 L, and generates a detailed daily irrigation strategy. This study offers a significant model reference and a technical pathway for developing agricultural irrigation systems that are both economical and efficient. Full article

Gas analyzers in post-combustion CO₂ capture plants are accurate but slow and sequential, yielding sparse, non-synchronous concentration records across absorber stages. We address this missing-data problem by reconstructing continuous CO₂ profiles with Moving Horizon Estimation (MHE) constrained by a mechanistic absorber model and available measurements; these MHE reconstructions are used as supervisory labels to train an end-to-end Stacked Denoising Autoencoder–Gated Recurrent Unit (SDAE-GRU) model. At run time, we deploy a hybrid soft sensor using the SDAE-GRU together with the mechanistic model and fuse their open-loop predictions via covariance-weighted blending with Gaspari-Cohn localization. We validate this approach on a pilot-scale MEA absorber using data from seven pilot runs conducted at distinct operating conditions, using datasets 1–5 for training/tuning and 6–7 for blind validation. On the blind validation runs, the hybrid estimator achieves a MAPE of 3.79% for stage-wise CO₂ predictions (averaged over all stages and time samples), outperforming both constituents evaluated standalone: 7.86% for the GRU-only soft sensor and 6.79% for the mechanistic model. Because MHE is used only offline to generate labels and to estimate model-error covariances, the deployed estimator is lightweight and suitable for online monitoring. Full article

The artisanal harvesting of Anadara mazatlanica is of fundamental importance to the sociocultural identity and economic livelihood of the coastal communities located in the San Ignacio–Navachiste–Macapule (SINM) lagoon system in Mexico; its conservation depends on the sustainable use of the species and its habitat, which is considered vulnerable to multiple socioeconomic and environmental pressures. The circular economy (CE) emerges as a potential approach to integrate resource exploitation, waste reduction, and community-oriented conservation management. This study analyzed the perceptions of A. mazatlanica harvesters, covering social, economic, environmental, and recycling dimensions (theoretical approach) and corroborated by exploratory factor analysis, thereby identifying the main challenges and areas of opportunity for the transition to sustainable development models. A quantitative (exploratory–descriptive) approach was used, employing a structured questionnaire that included a sociodemographic section and 23 items on a Likert scale. The findings revealed a high sociocultural appreciation of artisanal fishing and community cohesion ($\overline{\mathrm{x}}$ = 4.55). In contrast, economic perceptions showed a moderately negative level ($\overline{\mathrm{x}}$ = 2.48), indicating a dependence on intermediaries, limited added value, and institutional support. The CE dimension ($\overline{\mathrm{x}}$ = 1.55) suggested an underutilization of shells. In addition, the mean value of 3.44 for environmental perceptions highlighted awareness of ecosystem deterioration and regulatory deficiencies. These results highlight the need to enhance fisheries governance, diversify value chains, and integrate circular innovations to ensure the sustainability of this fishery. Full article

Based on monolithic microwave integrated circuit (MMIC) technology, this paper presents the design and implementation of a low-cost, highly integrated Ka-band sixteen-channel transmit/receive (T/R) module, specifically tailored to meet the application requirements of phased array antennas in airborne and spaceborne radar systems, satellite communications, and 5G/6G millimeter-wave networks. The proposed module employs an MMIC-based single-channel dual-chip discrete architecture, optimally integrating amplitude-phase multifunction chips and transmit-receive multifunction chips in terms of both fabrication process and performance characteristics, achieving a favorable balance between high performance and high-integration density. Using low-cost, low-temperature co-fired ceramic (LTCC) substrates, full-silver conductive paste, and a nickel–palladium–gold plating process, a novel “back-to-back” thin-slice packaging technique is presented to improve integration, lower manufacturing costs, and boost long-term reliability. Furthermore, the design incorporates glass insulators and a direct array interconnection scheme, which significantly minimizes transmission losses and reduces interface dimensions. The final module measures 70.3 mm × 26.2 mm × 10.9 mm and weighs only 34 g. Experimental results demonstrate a transmit output power of at least 23 dBm, a receive gain exceeding 26 dB, and a noise figure below 3.5 dB, achieving a 22.5–58% reduction in volume per channel while maintaining competitive RF performance. To improve testing effectiveness and guarantee data consistency, an automated radio frequency (RF) test system based on Python 3.11.5 was also developed. This work provides a practical technical approach for the engineering realization of Ka-band phased array systems. Full article

Achieving the “Dual Carbon” goals requires accelerating the near-zero energy transition of office buildings. Existing research focuses on isolated economic or technical dimensions, neglecting the dynamic evolution of tripartite collaboration among the government, developers, and users, and lacking integrated quantification of key drivers like carbon reduction, energy savings, and comfort benefits. To address this, this study develops a tripartite evolutionary game model that incorporates technical parameters, simulated with data from a nearly zero-energy office building (NZEOB). Results show that the transition is stage-dependent, shifting from initial government drive to long-term market sustainment. The economic benefits from energy savings emerge as the core decision factor in current technology adoption, often exerting a stronger influence than carbon reduction benefits, while improvements in comfort can effectively accelerate market acceptance. Technology pathways need to align with developmental stages; low-cost technologies are advisable in the early phase to lower entry barriers, whereas medium to later stages should focus on technologies with high combined benefits and system integration. Policy instruments should be dynamically optimized, with an emphasis on strengthening penalty mechanisms to establish rules in the early stage, shifting toward performance-linked incentives in the mid-to-late stages, and emphasizing compensation mechanisms to build trust. This study offers a basis for multi-party collaboration and stage-adapted strategies. Full article

This article examines the governance of Global Value Chains (GVCs) through the lens of economic competence based on a systematic literature review of 32 selected studies. The findings show that economic competence functions as a governance-contingent construct whose effects vary across hierarchical, captive, relational, and modular governance structures. Rather than directly determining upgrading outcomes, competence dimensions operate through governance repositioning and shifts in dependence asymmetries within value chains. The review identifies recurring mechanisms—such as substitutability reduction, coordination cost mitigation, and institutional alignment—that explain how competence and governance interact. The analysis further demonstrates that economic competence is multidimensional, encompassing innovation-oriented, market-oriented, decision-making, relational, and systemic components. These dimensions operate differently depending on coordination complexity and power distribution within the chain. By advancing a contingency-based framework, the study refines GVC governance theory through a micro-foundational explanation of upgrading dynamics. From a managerial perspective, the framework offers a structured tool for aligning competence development strategies with specific governance configurations, supporting informed capability investments and improved strategic positioning. Overall, the study contributes by systematically integrating competence theory with governance typologies and power asymmetries, providing a coherent analytical model for future empirical research. Full article

Premature wear and thermal degradation of friction linings can be significant limitations of conventional single-plate dry clutch systems under repeated engagement and high torque conditions. This study proposes a mechanically modified clutch incorporating an auxiliary spring-steel annular ring lining intended to promote staged engagement and potential load sharing between two friction interfaces. Analytical torque capacity was estimated using uniform wear theory, and experimental validation was conducted on a laboratory clutch test rig under both continuous and cyclic engagement conditions. Mass loss, thickness reduction, surface temperature, and wear morphology were measured. Under the tested laboratory conditions, the modified clutch exhibited a 28–30% reduction in friction lining mass loss, approximately 6% reduction in thickness loss, and an estimated increase in service life of about 4.4 × 10⁷ revolutions (~7%) compared with a conventional clutch. Lower measured surface temperatures were also observed for the modified configuration, which may be associated with redistribution of frictional work. The results suggest that staged mechanical engagement through an auxiliary spring-steel ring lining can improve wear performance while retaining the basic architecture of a single-plate clutch without substantial change to overall dimensions. Full article

This paper proposes a small size meander-line patch antenna which is designed to have biomedical telemetry applications using the Industrial, Scientific and Medical (ISM) band from 2.40 to 2.48 GHz supported by the equivalent circuit model (ECM). Antenna miniaturization is realized by the effective use of several slot structures placed in the rectangular microstrip patch structure, in order to realize electrical length extension and reduce the physical size. The antenna has overall dimensions of 12 × 22 × 0.787 mm³ and is made on a low-loss Arlon AD 450 (ε_r = 4.50 and tanδ = 0.0035) dielectric substrate, which has the desired stable electrical behavior and, importantly, can be used in implantable environments. Experimental validation is done by implanting the fabricated prototype into a laboratory-manufactured tissue-mimicking phantom, and it showed good agreement with simulated results. The designed antenna has a peak gain of 1.29 dBi in free space and −24.99 dBi at a frequency of 2.45 GHz and a fractional impedance bandwidth of about 250 MHz, which will guarantee reliable operation in the face of diversity and fluctuation in the surrounding environment (biological tissues). Furthermore, specific absorption rate (SAR) analysis is carried out in order to comply with international safety standards with peak SAR values kept within the permissible level of 2 W/kg for 10 g averaging tissue. The results show that the proposed antenna provides a good trade-off between the reduction in size, radiation performance and safety to the patient, making it a good candidate for short-range in-body wireless communication, implantable medical devices, and biomedical monitoring systems. Full article

Institutions are widely recognized as a key determinant of long-run economic growth, yet empirical research has predominantly focused on institutional levels rather than institutional stability over time. This study examines whether regulatory volatility—conceptualized as a dynamic dimension of institutional stability—is associated with economic growth across 32 European economies over the period 2004–2023. Regulatory volatility is measured using rolling five-year standard deviations of the Regulatory Quality indicator from the Worldwide Governance Indicators, allowing institutional stability to vary within countries over time while avoiding forward-looking bias. The empirical strategy relies on fixed-effects panel models with Driscoll–Kraay standard errors to account for unobserved heterogeneity and cross-sectional dependence. The results indicate that regulatory volatility is negatively associated with economic growth within European Union economies, while the relationship appears weaker and heterogeneous in Western Balkan transition countries. A one standard deviation increase in regulatory volatility is associated with an economically meaningful reduction in annual per capita growth. These findings suggest that sustainable economic performance may depend not only on the level of institutional quality but also on the stability and predictability of regulatory frameworks over time. Full article