Search Results (1,300)

To enhance the hydraulic performance of the Venturi injector, the effects of the structural parameters were investigated using response surface methodology (RSM) and computational fluid dynamics (CFD) simulations. The fertilizer suction chamber diameter, contraction angle, and throat diameter ratio were chosen as variables, while the suction flow rate, suction concentration, and suction efficiency were selected as performance indicators. Multiple regression models were established, and the regression models were used for parameter optimization and experimental verification. The results showed that under the same inlet-outlet differential pressure, with the increase in the fertilizer suction chamber diameter, contraction angle, and throat diameter ratio, the suction flow rate, suction concentration, and suction efficiency showed a trend of first increasing and then decreasing, and there were peaks in suction performance. Predictive regression equations were established for the suction flow rate, concentration, and efficiency within the experimental parameter range. The determination coefficients of the three regression equations were 0.9987, 0.9961, and 0.9990, respectively, which indicated that the established regression equations could be used for performance prediction. The optimized combination of structural parameters included a fertilizer suction chamber diameter of 32 mm, a contraction angle of 35°, and a throat diameter ratio of 2.93. The error between the predicted and experimental values was less than 3%, indicating a high level of reliability in the predictive regression model. The performance indicators of the optimized Venturi injector were significantly improved, with an increase of 124.1~793.7 L h⁻¹ in the suction flow rate, 9.52~16.42 percentage points in suction concentration, and 5.4~9.19 percentage points in suction efficiency. Full article

This study investigated the effects of combining sodium alginate (ALG) with various natural hydrocolloids on the microstructure and release behaviors of microbeads. The encapsulation solutions were prepared at a 1:1 (w/w) ratio with ALG as the control and carrageenan (CAR), locust bean gum (LBG), acacia gum (ACA), pectin (PEC), and carboxymethyl cellulose (CMC) as experimental groups. Each formulation contained 0.2% (w/v) tartrazine and was extruded into a CaCl₂ solution for bead production. Encapsulation efficiency varied across formulations, with the lowest in the control (ALG-ALG) and highest in ALG-CAR and ALG-CMC, reaching 74% and 78%, respectively. The microbead sizes ranged from 2.07 to 3.48 mm, with the lowest particle diameter observed in ALG-ACA composites. Surface analysis showed smooth and uniform microbeads in the control (ALG-ALG), while ALG-LBG microbeads were rougher. Release kinetics were assessed using various models, with the Higuchi model best describing the release for most formulations (highest R² values). Tartrazine release followed pseudo-Fickian behavior in all formulations, with slower release in ALG-ACA and faster release in ALG-LBG microbeads. This study fills a gap in understanding how the incorporation of different natural hydrocolloids influences both the encapsulation efficiency and release dynamics of alginate-based microbeads, providing valuable insights for applications in food and pharmaceutical industries. Full article

A three-dimensional numerical investigation using ethylene–oxygen was conducted to examine the characteristics of detonation waves in a non-premixed rotating detonation engine (RDE) across three equivalence ratio conditions: fuel-lean, stoichiometric, and fuel-rich. The study aims to identify the distinct timescales associated with detonation wave propagation within the combustor and to analyze their impact on detonation wave behavior, emphasizing the influence of equivalence ratio and injector behavior on detonation wave characteristics. The results indicate that the wave behavior varies with mixture concentration, with the ethylene injector demonstrating greater stiffness compared to the oxygen injector. In lean mixtures, characterized by excess oxidizer, waves exhibit less intensity and slower progression toward equilibrium, resulting in prolonged reaction times. Rich mixtures, with excess fuel, also show a delayed approach to equilibrium and an extended chemical reaction timescale. In contrast, the near-stoichiometric mixture achieves efficient combustion with the highest thermicity, rapidly reaching equilibrium and exhibiting the shortest chemical reaction timescale. Overall, the induction timescale is generally 2–3 times longer than its respective chemical reaction timescale, while the equilibrium timescale spans a broad range, reflecting the complex, rapid dynamics inherent in these chemical processes. This study identifies the role of the characteristic chemical timescale in influencing the progression of pre-detonation deflagration in practical RDEs. Prolonged induction times in non-ideal conditions, such as those arising from equivalence ratio variations, promote incomplete reactions, thereby contributing to pre-detonation phenomena and advancing our understanding of the underlying flow physics. Full article

Purpose: Accurate and precise navigation in space and postural stability rely on the central integration of multisensory input (vestibular, proprioceptive, visual), weighted according to its reliability, to continuously update the internal estimate of the direction of gravity. In this study, we examined both peripheral and central vestibular functions in a world-renowned 53-year-old male tightrope walker and investigated the extent to which his exceptional performance was reflected in our findings. Methods: Comprehensive assessments were conducted, including semicircular canal function tests (caloric irrigation, rotatory-chair testing, video head impulse testing of all six canals, dynamic visual acuity) and otolith function evaluations (subjective visual vertical, fundus photography, ocular/cervical vestibular-evoked myogenic potentials [oVEMPs/cVEMPs]). Additionally, static and dynamic posturography, as well as video-oculography (smooth-pursuit eye movements, saccades, nystagmus testing), were performed. The participant’s results were compared to established normative values. High-resolution diffusion tensor magnetic resonance imaging (DT-MRI) was utilized to assess motor tract integrity. Results: Semicircular canal testing revealed normal results except for a slightly reduced response to right-sided caloric irrigation (26% asymmetry ratio; cut-off = 25%). Otolith testing, however, showed marked asymmetry in oVEMP amplitudes, confirmed with two devices (37% and 53% weaker on the left side; cut-off = 30%). Bone-conducted cVEMP amplitudes were mildly reduced bilaterally. Posturography, video-oculography, and subjective visual vertical testing were all within normal ranges. Diffusion tensor MRI revealed no structural abnormalities correlating with the observed functional asymmetry. Conclusions: This professional tightrope walker’s exceptional balance skills contrast starkly with significant peripheral vestibular (otolithic) deficits, while MR imaging, including diffusion tensor imaging, remained normal. These findings highlight the critical role of central computational mechanisms in optimizing multisensory input signals and fully compensating for vestibular asymmetries in this unique case. Full article

In the context of mobile phones, the local optimal global navigation satellite systems (GNSS) shadow matching algorithm, which is based on the urban three-dimensional model, can effectively reduce the error of GNSS pseudo-range single-point positioning. However, the positioning accuracy of this algorithm is susceptible to noise, and its continuous signal-to-noise ratio (SNR) scoring method does not fully exploit the probability density and probability distribution information contained in the SNR. Therefore, this paper proposes two improvements for the local optimal shadow matching algorithm: (1) utilizing low-pass filtering to filter SNR, thereby reducing the influence of noise on the algorithm and (2) introducing a probability-based SNR scoring method to fully leverage the probability density and probability distribution information of SNR. In dynamic single-point positioning, the improved algorithm attains an absolute positioning accuracy of up to 3 m, representing a decimeter-level enhancement over the original algorithm. Experiments confirm that using the SNR statistical information of non-line of sight (NLOS) and line-of-sight (LOS) as prior information results in better positioning accuracy compared to when this information is distorted by multipath effects. Additionally, to address the issue of high time complexity in the shadow matching algorithm, especially when considering local optima, this paper presents a scheme to simplify the algorithm’s flow, reducing its time complexity by approximately 75%. Full article

Achieving simultaneous anammox and denitrification is a feasible approach for enhancing nitrogen removal in mainstream anammox processes. Nevertheless, the optimal C/N range and microbial dynamics driving this process are still not fully understood. In this study, three mainstream anammox reactors were operated with varying influent C/N ratios. The results demonstrated a remarkable nitrogen removal of 92.6% achieved by combining partial denitrification and anammox with the C/N ratio set at 1.0. However, the nitrogen removal efficiency decreased when the C/N ratio was either 0.5 or 2.0, causing the accumulation of nitrate and ammonium in the effluent, respectively. These results suggest a narrow optimal range of the influent C/N for mainstream anammox processes. Additionally, a transition in the predominant denitrifier population from Denitratisoma to Thauera was noted when the C/N ratio increased. The denitrifying phenotype of Thauera was significantly influenced by the C/N ratio. Thauera can effectively collaborate with anammox bacteria only at a suitable C/N ratio, where it partially reduces the nitrate generated in the anammox reaction. With a high influent C/N, Thauera primarily performed nitrite reduction, notably inhibiting anammox activity. The results of this study are valuable for the optimal design of the mainstream anammox process. Full article

This study investigated the population dynamics, growth, reproduction, and parasitism of Penaeus aztecus over a 27-month period in Antalya Bay (Eastern Mediterranean). P. aztecus was the most abundant shrimp species, comprising 53.4% of the collected shrimp specimens. Abundance varied seasonally, with peak densities in summer. Males had a smaller mean carapace length (CL) of 25.8 mm compared to females at 30.2 mm. Females dominated larger size classes, with all individuals ≥ 46 mm CL being female. The sex ratio was balanced at 1:1, with no seasonal variations. Spawning occurred year-round, peaking in June, late summer, and November. Females displayed four ovarian stages, with the first mature size (FMS) at 36 mm CL. Parasitism by Epipenaeon ingens reduced the density of mature females, with 42% of potential spawners failing to develop gonads. The prevalence of parasitism showed seasonal variation and was inversely correlated with sea surface temperature (SST). Marine recruitment occurred from June to November, with a peak between July and September. Growth analysis revealed faster rates in females, while males reached a smaller maximum size. This study also identified inefficiencies in gear selectivity, with many juvenile shrimp (below recruitment size) being retained. Trawl efficiency improved with the use of turtle excluder devices (TEDs), which reduced bycatch of nontarget species, such as loggerhead turtles and cartilaginous fishes. The instantaneous total mortality rate (Z) ranged from 0.658 to 0.026 month⁻¹ for male shrimp and from 1.00 to 0.014 month⁻¹ for female shrimp, with survival sharply declining after recruitment, leaving only about 3.6% of individuals surviving beyond 10 months. Full article

Since the early 20th century, dimensional analysis and similarity arguments have provided a critical tool for the analysis of scientific, engineering, and thermodynamic systems. Traditionally, the resulting dimensionless groups are categorized into those defined by (i) geometric similarity, involving ratios of length scales; (ii) kinematic similarity, involving ratios of velocities or accelerations, and (iii) dynamic similarity, involving ratios of forces. This study considers an additional category based on entropic similarity, with three variants defined by the following: (i) ratios of global or local entropy production terms Π entrop = σ ˙ 1 / σ ˙ 2 or Π ^ entrop = σ ˙ ^ 1 / σ ˙ ^ 2 ; (ii) ratios of entropy flow rates Π entrop = F S , 1 / F S , 2 or magnitudes of entropy fluxes Π ^ entrop = | | j S 1 | | / | | j S 2 | | ; and (iii) the ratio of a fluid velocity to that of a carrier of information Π info = U / c . Given that all phenomena involving work against friction, dissipation, spreading, chemical reaction, mixing, separation, or the transmission of information are governed by the second law of thermodynamics, these are more appropriately analyzed directly in terms of competing entropic phenomena and the dominant entropic regime, rather than indirectly using ratios of forces. This work presents the entropic dimensionless groups derived for a wide range of diffusion, chemical reaction, dispersion, and wave phenomena, revealing an entropic interpretation for many known dimensionless groups and many new dimensionless groups. Full article

Reproductive biology patterns are crucial for understanding the dynamics and evolution of plants. This is particularly relevant in bryophytes, where sex expression and reproductive success can vary significantly with environmental conditions. Islands, with their isolated and diverse environments, provide natural laboratories to explore these dynamics. In this study, we investigate sex expression, the phenotypic sex ratio, and sporophyte production in one moss (Exsertotheca intermedia) and three liverwort species (Frullania polysticta, Frullania teneriffae, Porella canariensis) across their entire distribution range. Depending on the species, the geographic range includes the Canary Islands, Madeira, the Azores, the Iberian Peninsula, the British Isles, and the Faroe Islands. For the non-Macaronesian endemic species (F. teneriffae, P. canariensis) higher levels of sex expression and males were found in the Macaronesian archipelagos. In leafy liverworts, females appear to be correlated with lower temperatures and higher precipitation levels, while males seem to be associated with higher temperatures and relatively lower precipitation levels. In this study, we demonstrated that bryophyte populations from Macaronesia exhibited higher levels of sex expression compared to their continental counterparts, suggesting that the distinct environmental conditions of these islands play a crucial role in shaping their reproductive patterns. Full article

This paper introduces an analog differential optoelectronic receiver (ADOR) integrated with digital slicers for short-range LiDAR systems, consisting of a spatially modulated P⁺/N-well on-chip avalanche photodiode (APD), a cross-coupled differential transimpedance amplifier (CCD-TIA) with cross-coupled active loads, a continuous-time linear equalizer (CTLE), a limiting amplifier (LA), and dual digital slicers. A key feature is the integration of an additional on-chip dummy APD at the differential input node, which enables the proposed ADOR to outperform a traditional single-ended TIA in terms of common-mode noise rejection ratio. Also, the CCD-TIA utilizes cross-coupled PMOS-NMOS active loads not only to generate the symmetric output waveforms with maximized voltage swings, but also to provide wide bandwidth characteristics. The following CTLE extends the receiver bandwidth further, allowing the dual digital slicers to operate efficiently even at high sampling rates. The LA boosts the output amplitudes to suitable levels for the following slicers. Then, the inverter-based slicers with low power consumption and a small chip area produce digital outputs. The fabricated ADOR chip using a 180 nm CMOS process demonstrates a 20 dB dynamic range from 100 μA_pp to 1 mA_pp, 2 Gb/s data rate with a 490 fF APD capacitance, and 22.7 mW power consumption from a 1.8 V supply. Full article

A programmable gain amplifier (PGA) is commonly used to optimize the input dynamic range of high-performance systems such as headphones and biomedical sensors. But PGA is rather sensitive to electromagnetic interference (EMI), which limits the precision of these systems. Many capacitor-less low-dropout regulator (LDO) schemes with high power supply rejection have been proposed to act as the independent power supply for PGA, which consumes additional power and area. This paper proposed a PGA with a high power supply rejection ratio (PSRR) and low power consumption, which serves as the analog front-end amplifier in the 20-bit sigma-delta ADC. The PGA is a two-stage amplifier with hybrid compensation. The first stage is the recycling folded cascode amplifier with the gain-boost technique, while the second stage is the class-AB output stage. The PGA was implemented in the 0.18 μm CMOS technology and achieved a 9.44 MHz unity-gain bandwidth (UGBW) and a 57.8° phase margin when driving the capacitor of 5.9 pF. An optimum figure-of-merit (FoM) value of 905.67 has been achieved with the proposed PGA. As the front-end amplifier of a high-precision ADC, it delivers a DC gain of 162.1 dB, the equivalent input noise voltage of 301.6 nV and an offset voltage of 1.61 μV. Within the frequency range below 60 MHz, the measured PSRR of ADC is below −70 dB with an effective number of bits (ENOB), namely 20 bits. Full article

In this paper, a CMOS optoelectronic analog front-end (AFE) preamplifier with cross-coupled active loads for short range LiDAR applications is presented, which consists of a spatially modulated P⁺/N-well on-chip avalanche photodiode (APD), the differential input stage with cross-coupled active loads, and an output buffer. Particularly, another on-chip dummy APD is inserted at the differential input node to improve the common-mode noise rejection ratio significantly better than conventional single-ended TIAs. Moreover, the cross-coupled active loads are exploited at the output nodes of the preamplifier not only to help generate symmetric output waveforms, but also to enable the limiting operations even without the following post-amplifiers. In addition, the inductive behavior of the cross-coupled active loads extends the bandwidth further. The proposed AFE preamplifier implemented in a 180-nm CMOS process demonstrate the measured results of 63.5 dB dynamic range (i.e., 1 µA_pp~1.5 mA_pp input current recovery), 67.8 dBΩ transimpedance gain, 1.6 GHz bandwidth for the APD capacitance of 490 fF, 6.83 pA⁄√Hz noise current spectral density, 85 dB power supply rejection ratio, and 32.4 mW power dissipation from a single 1.8 V supply. The chip core occupies the area of 206 × 150 µm². Full article

With the development of a power system predominantly reliant on new energy sources, turbine generator sets are increasingly required to operate under wide load conditions, resulting in numerous unstable flow phenomena and substantial economic losses for power stations. This study employs the Shear Stress Transport (SST) k-ω turbulence model to combine numerical simulations with experimental methods. It calculates the guide vane opening at the rated head of a Francis turbine and examines the internal flow field characteristics and pressure pulsations under various operating conditions. The findings indicate that the entropy production ratio in the draft tube is the highest among all load conditions, ranging from about 72.7% to 95.9%. Energy dissipation in the vaneless zone and the runner increases with greater opening. At 45% and 100% load conditions, the draft tube is mainly influenced by dynamic and static interference, single and double frequencies induced by runner rotation, and low-frequency fluctuations of the vortex and. Under 60% load conditions, pressure fluctuations in the draft tube are primarily caused by the eccentric vortex band, characterized by higher intensity and a frequency of 0.2 f_n. Numerical results closely align with experimental observations. The findings provide essential guidance for ensuring the stable operation of power plant units. Full article

Air pollution in urban street canyons presents a serious health risk, especially in densely populated areas. While previous research has explored airflow characteristics in these canyons, it often lacks detailed data on pollutant dispersion and the effects of wind speed on airflow patterns and vortex formation. This study uses Computational Fluid Dynamics (CFD) to deliver quantitative measurements of pollutant dispersion rates and qualitative insights into airflow patterns across various street canyon morphologies. The analysis examines a range of aspect ratios (ARs), from wide (AR = 0.75) to narrow (AR = 4.5), and different wind speeds to evaluate their effects on pollutant dispersion. Findings indicate that purging flow rates decline as the AR increases, with a more pronounced decrease at lower AR values. In narrower streets, airflow patterns are particularly sensitive to wind velocity, leading to unexpected vortices that hinder effective pollutant dispersion. By incorporating these insights into urban design strategies, cities can enhance street ventilation, thereby reducing pollutant concentrations and improving public health. This study also tests a specific street layout in Seville to predict pollutant accumulation under various conditions, assessing health risks based on World Health Organization guidelines. Ultimately, this research aids in developing healthier, more sustainable urban environments. Full article

Anaerobic digestion (AD) is a waste-to-energy strategy that leverages natural microbiological processes. It is increasingly used in farms to treat manure, resulting in biogas for energy production and digestate as fertiliser. However, animal manure often contains antibiotic (AB) residues, raising concerns about their impact on AD efficiency and their potential spread through digestate use. This multidisciplinary study evaluated the effects of an AB mixture (enrofloxacin, ciprofloxacin and sulfamethoxazole) on CH₄ production, microbial community (Fungi, Bacteria and Archaea) dynamics and antibiotic resistance gene (ARG) presence. The experiment used a cattle manure/digestate ratio of 1:35, typical of real digesters, with AB concentrations set at low (2.5 mg kg⁻¹ each) and high (7.5 mg kg⁻¹ each) levels. The ABs affected cumulative CH₄ production (ranging from 5939 to 6464 mL) only at the highest concentration. After 51 days, sulfamethoxazole reached residual levels, while enrofloxacin and ciprofloxacin were only partially degraded (<50%), but ARGs were significantly reduced. The microbial community, particularly prokaryotes, exhibited resilience, maintaining efficient CH₄ production. Overall findings strongly suggest that AD is an effective treatment for producing energy and good fertiliser, also reducing AB and ARG content as well as mitigating CH₄ emissions into the atmosphere. Full article