Search Results (240)

Lithium–sulfur batteries (LSBs) exhibit high theoretical specific capacities, abundant resource reserves, and low costs, making them promising candidates for next-generation lithium-ion batteries (LIBs). However, significant challenges, such as the shuttle effect and volume expansion, hinder their practical applications. To address these issues, this study introduces a unique intermediate layer comprising N-doped carbon nanofiber/TiO₂/diatomite (NCNF/TiO₂/DE) from the perspective of membrane modification. The intermediate layer comprises nitrogen-doped titanium dioxide/carbon nanofiber (NCNF/TiO₂) materials, with diatomite filling the fiber gaps. This forms a three-dimensional (3D) conductive network that provides ample space for sulfur volume expansion and numerous adsorption active sites, thereby accelerating electrolyte penetration and lithium-ion diffusion. These features collectively contribute to the outstanding electrochemical performance of the battery. At 0.1 C, the NCNF/TiO₂/DE-800-coated separator battery achieved a first-cycle discharge specific capacity of 1311.1 mAh g⁻¹, significantly higher than the uncoated lithium–sulfur battery (919.6 mAh g⁻¹). Under varying current densities, the NCNF/TiO₂/DE-800 material demonstrates good electrochemical reversibility and exhibits high lithium-ion diffusion rates and low charge-transfer resistance. Therefore, this study provides an advanced intermediate layer material that enhances the electrochemical performance of lithium–sulfur batteries. Full article

Low-power portable devices play a major role in IoT applications, where the analog-to-digital converters (ADCs) are very important components for the processing of analog signals. In this paper, a 5-bit two-step flash ADC with a low-power double-tail dynamic comparator (DTDC) using the control switching technique is presented. The most significant bit (MSB) in the proposed design is produced by only one low-power DTDC in the first stage, and the remaining bits are generated by the flash ADC in the second stage with the help of an auto-control circuit. A control circuit produced reference voltages with respect to the control input and mid-point voltage (${\mathrm{V}}_k$). The proposed design and simulations are carried out using 90 nm CMOS technology. The result shows that the peak differential non-linearity (DNL) and integral non-linearity (INL) are +0.60/−0.69 and +0.66/−0.40 LSB, respectively. The signal-to-noise and distortion ratio (SNDR) for an input signal having a frequency of 1.75 MHz is found to be 30.31 dB. The total power consumption of the proposed design is significantly reduced, which is 439.178 $\mathsf{\mu }$W for a supply voltage of 1.2 V. The figure of merit (FOM) is about 0.054 pJ/conversion step at 250 MS/s. The present design provides low power consumption and occupies less area compared to the existing works. Full article

In order to address the inconsistency problem caused by parasitic backend wiring among multiple ramp generators and among multiple columns in large-array CMOS image sensors (CIS), this paper proposes a high-precision compensation technology combining average voltage technology, adaptive negative feedback dynamic adjustment technology, and digital correlation double sampling technology to complete the design of an adaptive ramp signals inconsistency calibration scheme. The method proposed in this article has been successfully applied to a CIS with a pixel array of 8192(H) × 8192(V), based on the 55 nm 1P4M CMOS process, with a pixel size of $10\times 10\mathsf{\mu }{\mathrm{m}}^2$. The chip area is 88(H) × 89(V) ${\mathrm{mm}}^2$, and the frame rate is 10 fps. The column-level analog-to-digital converter is a 12-bit single-slope analog-to-digital converter (SS ADC). The experimental results show that the ramp generation circuit proposed in this paper can reduce the inconsistency among the ramp signals to 0.4% LSB, decreases the column fixed pattern noise (CFPN) caused by inconsistent ramps of each column to 0.000037% (0.15 $e^{-}$), and increases the overall chip area and power consumption by only 0.6% and 0.5%, respectively. This method provides an effective solution to the influence of non-ideal factors on the consistency of ramp signals in large area array CIS. Full article

In the realm of marine science and engineering, hydrofoils play a pivotal role in the efficiency and performance of marine turbines and water-jet pumps. In this investigation, the boundary layer characteristics of an NACA0009 hydrofoil with a blunt trailing edge are focused on. The effectiveness of both the two-equation gamma theta (γ-Re_θt) transition model and the one-equation intermittency (γ) transition model in forecasting boundary layer behavior is evaluated. When considering natural transition, these two models outperform the shear stress transport two-equation (SST k-ω) turbulence model, notably enhancing the accuracy of predicting boundary layer flow distribution for chord-length Reynolds numbers (Re_L) below 1.6 × 10⁶. However, as Re_L increases, both transition models deviate from experimental values, particularly when Re_L is greater than 2 × 10⁶. The results indicate that the laminar separation bubble (LSB) is sensitive to changes in angles of attack (AOA) and Re_L, with its formation observed at AOA greater than 2°. The dimensions of the LSB, including the initiation and reattachment points, are found to contract as Re_L increases while maintaining a constant AOA. Conversely, an increase in AOA at similar Re_L values leads to a reduced size of the LSB. The findings are essential for the design and performance optimization of water-jet pumps, particularly in predicting and flow separation and transition phenomena. Full article

Analyzing irrigation patterns to promote efficient water use in urban areas is challenging. Analysis of irrigation by remote sensing (AIRS) combines multispectral aerial imagery, evapotranspiration data, and ground-truth measurements to overcome these challenges. We demonstrate AIRS on eight neighborhoods in Weber County, Utah, using 0.6 m National Agriculture Imagery Program (NAIP) and 0.07 m drone imagery, reference evapotranspiration (ET), and water use records. We calculate the difference between the actual and hypothetical water required for each parcel and compare water use over three time periods (2018, 2021, and 2023). We find that the quantity of overwatering, as well as the number of customers overwatering, is decreasing over time. AIRS provides repeatable estimates of irrigated area and irrigation demand that allow water utilities to track water user habits and landscape changes over time and, when controlling for other variables, see if water conservation efforts are effective. In terms of image analysis, we find that (1) both NAIP and drone imagery are sufficient to measure irrigated area in urban settings, (2) the selection of a threshold value for the normalized difference vegetation index (NDVI) becomes less critical for higher-resolution imagery, and (3) irrigated area measurement can be enhanced by combining NDVI with other tools such as building footprint extraction, object classification, and deep learning. Full article

Lithium–sulfur batteries (LSB) have been recognized as a prominent potential next-generation energy storage system, owing to their substantial theoretical specific capacity (1675 mAh g⁻¹) and high energy density (2600 Wh kg⁻¹). In addition, sulfur’s abundance, low cost, and environmental friendliness make commercializing LSB feasible. However, challenges such as poor cycling stability and reduced capacity, stemming from the formation and diffusion of lithium polysulfides (LiPSs), hinder LSB’s practical application. Introducing functional separators represents an effective strategy to surmount these obstacles and enhance the electrochemical performance of LSBs. Here, we have conducted a comprehensive review of recent advancements in functional separators for LSBs about various (i) carbon and metal compound materials, (ii) polymer materials, and (iii) novel separators in recent years. The detailed preparation process, morphology and performance characterization, and advantages and disadvantages are summarized, aiming to fundamentally understand the mechanisms of improving battery performance. Additionally, the development potential and future prospects of advanced separators are also discussed. Full article

This paper presents a non-return-to-zero (NRZ)/4-level pulse amplitude modulation (PAM-4) dual-mode wireline transmitter with an eye-opening enhancement technique to improve horizontal eye-opening. With the eye-enhancement pulse generator and the auxiliary pull-up device in the tail-less current-mode driver, the worst-case horizontal eye-opening increased by 30% in the PAM-4 eye diagram. The power efficiency of the NRZ mode was also improved by completely turning off the LSB path in the differential data path, resulting in only a 31% power efficiency degradation, which is far lower than that of the prior dual-mode transmitters. Fabricated in 28 nm CMOS, the transmitter achieves power efficiency of 1.4 pJ/bit at 56 Gb/s in PAM-4 mode and 1.84 pJ/bit at 28 Gb/s in NRZ mode, respectively. Full article

Digital histogram generation for time-resolved measurements with single-photon avalanche diode (SPAD) sensors requires the storage of many timestamp signals. This work presents a mixed-signal time-to-digital converter (TDC) that uses analog storage to achieve an area-efficient design that can be integrated in large SPAD arrays. Fabricated using a 150 nm CMOS process, the prototype occupies an area of only 18.3 µm × 36.5 µm, a notable size reduction compared to conventional designs. The experimental results demonstrated high performance, with an integral nonlinearity (INL) of 0.35/0.14 least significant bit (LSB) and a differential nonlinearity (DNL) of 0.14/−0.12 LSB. In addition, the proposed TDC can support the construction of histograms comprising up to 512 bins, making it an effective solution to accommodate a wide range of resolution requirements. Validated in a point-of-care (PoC) device for fluorescence lifetime measurements, it distinguished between lifetimes of approximately 4.1 ns, 3.6 ns and 80 ns with the Alexa Fluor (AF) 546 and 568 dyes and Quantum Dot (QD) 705, respectively. The analog storage design and area-efficient architecture offer a novel approach to integrating TDCs in SPAD-based systems, with potential applications in medical diagnostics and beyond. Full article

As a better alternative to lithium-ion batteries (LIBs), lithium–sulfur batteries (LSBs) stand out because of their multi-electron redox reactions and high theoretical specific capacity (1675 mA h g⁻¹). However, the long-term stability of LSBs and their commercialization are significantly compromised by the inherently irreversible transition of soluble lithium polysulfides (LiPS) into solid short-chain S species (Li₂S₂ and Li₂S) and the resulting substantial density change in S. To address these issues, we used activated carbon cloth (ACC) coated with Ni₁₂P₅ as a porous, conductive, and scalable sulfur host material for LSBs. ACC has the benefit of high electrical conductivity, high surface area, and a three-dimensional (3D) porous architecture, allowing for ion transport channels and void spaces for the volume expansion of S upon lithiation. Ni₁₂P₅ accelerates the breakdown of Li₂S to increase the efficiency of active materials and trap soluble polysulfides. The highly effective Ni₁₂P₅ electrocatalyst supported on ACC drastically reduced the severity of the LiPS shuttle, affected the abundance of adsorption–diffusion–conversion interfaces, and demonstrated outstanding performance. Our cells achieved near theoretical capacity (>1611 mA h g⁻¹) during initial cycling and superior capacity retention (87%) for >250 cycles following stabilization with a 0.05% decay rate per cycle at 0.2 C. Full article

Sea buckthorn is a promising ingredient for the food industry because it is a good source of vitamins, polyphenols, phytosterols, etc. In this research, it is the first time that aqueous extracts of lyophilized sea buckthorn (LSB) 0%, 0.5%, 1%, 2%, and 3% w/w were used to enrich set-type yogurts. Therefore, fermentation kinetics, hardness, color, titratable acidity, syneresis, water holding capacity, total phenolic content microstructure, and sensory analysis were investigated. Extracts of lyophilized sea buckthorn shorten the yogurt fermentation time, change the microstructure, reduce syneresis, and increase water-holding capacity compared to plain yogurt. Also, the titratable acidity for all yogurts remained the same but the total phenolic content of yogurts increased as the concentration of extracts from lyophilized sea buckthorn increased. The color parameters of the fortified set-type yogurts were affected by the color of the sea buckthorn extract with increasing a* and b* values according to extract concentrations. Finally, yogurts fortified with 0.5% and 1.0% w/w extracts of LSB have good quality characteristics, increased total phenolic content, and higher scores of being liked compared to the rest of the enriched samples. This study could increase the knowledge of the uses of aqueous extracts of lyophilized sea buckthorn in dairy products. Full article

Lithium–sulfur batteries (LSBs) are widely studied as an alternative to lithium-ion batteries, this emphasis being due to their high theoretical energy density and low cost, and to the high natural abundance of sulfur. Lithium polysulfide shuttling and lithium dendrite growth have limited their commercialization. Porous polyvinylidene fluoride (PVDF) separators have shown improved performance (relative to hydrocarbon separators) in lithium-ion batteries due to faster lithium-ion migration and higher Li⁺ transference number. A thin polar PVDF membrane has now been fabricated via phase inversion (an immersion-precipitation method) yielding a β (polar) phase concentration of 72%. Preparation from commercial PVDF used dimethylformamide (DMF) solvent at the optimized crystallizing temperature of 70 °C, and pores in the membrane were generated by exchange of DMF with deionized water as non-solvent. The polar PVDF film produced has the advantages of being ultrathin (15 µm), lightweight (1.15 mg cm⁻²), of high porosity (75%) and high wettability (84%), and it shows enhanced thermal stability relative to polypropylene (PP). The porous, polar PVDF membrane was combined with a commercially available PP membrane to give a hybrid, two-layer, separator combination for LSBs. A synergy was created in the two-layer separator, providing high sulfur utilization and curbing polysulfide shuttling. The electrochemical performance with the hybrid separator (PP–β-PVDF) was evaluated in LSB cells and showed good cyclability and rate capability: those LSB cells showed a stable capacity of 750 mA h g⁻¹ after 100 cycles at 0.1 C, much higher than that for otherwise-identical cells using a commercial PP-only separator (480 mA h g⁻¹). Full article

Lithium–sulfur batteries (LSBs) hold promise for use in next-generation high-energy-density energy storage systems. However, the commercial application of LSBs is hindered by the shuttle effect of polysulfides. In this study, we synthesized a covalent organic framework material (PY−DHBD−COF) and employed it to modify the separators of LSBs in order to buffer the shuttle effect of polysulfides. A modified separator, involving PY−DHBD−COF coating of the commercial Celgard 2500 PP separator, is prepared via a vacuum-assisted self-assembly method. The PY−DHBD−COF features hydroxyl and imine bonds, which can adsorb lithium polysulfides (LiPSs) and buffer the shuttle effect. The PY−DHBD−COF coating exhibits a thin thickness and oriented nanochannels, facilitating electrolyte wetting and Li⁺ transport. As a result, the LSBs with PY−DHBD−COF-modified separators exhibit a high specific capacity of 373 mAh g⁻¹ at 4 C with only 0.005% capacity decay per cycle after 450 cycles at 2 C, demonstrating an excellent cycling performance. Full article

In digital image security, the Josephus permutation is widely used in cryptography to enhance randomness. However, its application in steganography is underexplored. This study introduces a novel method integrating the Josephus permutation into the LSB 3-3-2 embedding technique for image steganography. This approach improves the randomness of the keystream generated by the chaotic logistic map, addressing vulnerabilities in basic logistic maps susceptible to steganalysis. Our algorithm is tested on RGB images as secret data, presenting higher complexity compared to grayscale images used in previous studies. Comparative analysis shows that the proposed algorithm offers higher payload capacity while maintaining image quality, outperforming traditional LSB techniques. This research advances the field of image steganography by demonstrating the effectiveness of the Josephus permutation in creating more secure and robust steganographic images. Full article

The Lanzhou Heavy Ion Research Facility (LIRF) is the largest heavy ion research facility in China, providing a substantial volume of experimental data for fundamental research in nuclear physics. The Topmetal-CEE is a pixel readout chip specifically designed for tracking detectors. Within the Topmetal-CEE framework, the front-end amplifier and comparator necessitate precisely adjustable bias voltages. Hence, in this paper, a 14-bit resolution DAC with an R-2R resistor network structure is designed, along with an amplifier featuring high driving capabilities as the DAC driver, thus preventing potential impedance issues when driving large pixel arrays. Test results demonstrate that the DAC module, operating under a 3.3 V supply voltage, can consistently output voltages ranging from 0 to 1.8 V. Furthermore, the differential non-linearity error is less than 1.07 LSB, and the integral non-linearity error is less than 1.57 LSB. Full article

In 2021, the Ingenuity helicopter performed the inaugural flight on Mars, heralding a new epoch of exploration. However, the aerodynamics on Mars present unique challenges not found on Earth, such as low chord-based Reynolds number flows, which pose significant hurdles for future missions. The Ingenuity’s design incorporated a Reynolds number of approximately 20,000, dictated by the rotor’s dimensions. This paper investigates the implications of flows at a Reynolds number of 50,000, conducting a comparative analysis with those at 20,000 Re. The objective is to evaluate the feasibility of using larger rotor dimensions or extended airfoil chord lengths. An increase in the Reynolds number alters the size and position of Laminar Separation Bubbles (LSBs) on the airfoil, significantly impacting performance. This study leverages previous research on the structure and dynamics of LSBs to examine the flow around a cambered plate with 6% camber and 1% thickness in Martian conditions. This paper details the methods and mesh used for analysis, assesses airfoil performance, and provides a thorough explanation of the results obtained. Full article