Search Results (150)

Quantum sensing based on NV-centers in diamonds has been demonstrated many times in multiple publications. The majority of publications use lasers in free space or lasers with fiber optics, expensive optical components such as dichroic mirrors, or beam splitters with dichroic filters and expensive detectors, such as Avalanche photodiodes or single photon detectors, overall, leading to custom and expensive setups. In order to provide an inexpensive NV-based magnetometer setup for educational use in schools, to teach the three topics, fluorescence, optically detected magnetic resonance, and Zeeman splitting, inexpensive, miniaturized, off-the-shelf components with high reliability have to be used. The cheaper such a setup, the more setups a school can afford. Hence, in this work, we investigated LEDs as light sources, considered different diamonds for our setup, tested different color filters, proposed an inexpensive microwave resonator, and used a cheap photodiode with an appropriate transimpedance amplifier as the basis for our quantum magnetometer. As a result, we identified cheap and functional components and present a setup and show that it can demonstrate the three topics mentioned at a hardware cost <EUR 100. Full article

The CRISPR/Cas system has attracted increasing attention in accurate nucleic acid detection. Herein, we reported a CRISPR/Cas12a-chemiluminescence cascaded bioassay (CCCB) for the amplification-free and sensitive detection of human papillomavirus type 16 (HPV-16) and parvovirus B19 (PB-19). A magnetic bead (MB)-linking single-stranded DNA (LssDNA)-alkaline phosphatase (ALP) complex was constructed as the core component of the bioassay. During the detection process, the single-stranded target DNA was captured and enriched by LssDNA and then activated the trans-cleavage activity of Cas12a. Due to the Cas12a-mediated cleavage of LssDNA, ALP was released from the MB, subsequently catalyzing the substrate to generate a chemiluminescence (CL) signal. Given the cascade combination of CRISPR/Cas12a with the CL technique, the limits of detection for HPV-16 and PB-19 DNA were determined as 0.14 pM and 0.37 pM, respectively, and the whole detection could be completed within 60 min. The practicality and reliability of the platform were validated through target-spiked clinical specimens, and the recovery rate was 93.4–103.5%. This dual-amplification strategy—operating without target pre-amplification—featured high specificity, low contamination risk, facile preparation, and robust stability. It provides a novel approach for sensitive nucleic acid detection, with the potential for rapid extension to the diagnosis of various infectious diseases. Full article

The quality of rice, one of the most important food crops in the world, is directly related to people’s dietary experience and nutritional health. With the improvement in living standards, consumer requirements for the taste quality of rice are becoming increasingly strict. Japonica rice occupies an important position in rice production due to its rich genetic diversity and excellent agronomic characteristics. In this study, LJ433, JY653, LJ218, LJ177, LY66, and LX21, which are mainly popularized in northern China and have different taste values, were selected as the experimental subjects, and YJ219, which won the gold award in the third China high-quality rice variety taste quality evaluation, was taken as the control (CK). Low-field nuclear magnetic resonance and spectral analysis were adopted as the main detection techniques. The effects of free water (peak area increased by 13.24–86.68% when p < 0.05), bound water, appearance characteristics (such as chalkiness, which decreased by 18.48–86.48%), and chemical composition (amylose content decreased by 3.76–26.47%) on the taste value of rice were systematically analyzed, and a multi-dimensional “appearance–palatability–nutrition” evaluation system was constructed. The experimental results indicated that increasing the free water content, reducing the chalkiness and chemical component content could significantly improve the taste value of rice (p < 0.05). The results of this research provide a theoretical basis for breeding new high-yield and high-quality rice varieties and have guiding significance for the practice of rice planting and processing. Full article

This study presents an analysis of the electromagnetic noise and vibration in a surface-mounted permanent magnet synchronous machine (SPMSM), focusing on their excitation sources. To investigate this, the excitation sources were identified through an analytical approach, and their effects on electromagnetic noise and vibration were evaluated using a finite element method (FEM)-based analysis approach. Additionally, an equivalent curved-beam model based on three-dimensional shell theory was applied to determine the deflection forces on the stator yoke, accounting for the tooth-modulation effect. The stator’s natural frequencies were derived through the characteristic equation in free vibration analysis. Modal analysis was performed to validate the analytically derived natural frequencies and to investigate stator deformation under the tooth-modulation effect across various vibration modes. Furthermore, noise, vibration, and harshness (NVH) analysis via FEM reveals that major harmonic components align closely with the natural frequencies, identifying them as primary sources of elevated vibrations. A comparative study between 8-pole–9-slot and 8-pole–12-slot SPMSMs highlights the impact of force variations on the stator teeth in relation to vibration and noise characteristics, with FEM verification. The proposed method provides a valuable tool for early-stage motor design, enabling the rapid identification of resonance operating points that may induce severe vibrations. This facilitates proactive mitigation strategies to enhance motor performance and reliability. Full article

The enduring manufacturing goals are increasingly shifting toward ultra-precision manufacturing and micro-nano fabrication, driven by the demand for sophisticated products. Unconventional machining processes such as electrochemical jet machining (ECJM), electrical discharge machining (EDM), electrochemical machining (ECM), abrasive water jet machining (AWJM), and laser beam machining (LBM) have been widely adopted as feasible alternatives to traditional methods, enabling the production of high-quality engineering components with specific characteristics. ECJM, a non-contact machining technology, employs electrodes on the nozzle and workpiece to establish an electrical circuit via the jet. As a prominent special machining technology, ECJM has demonstrated significant advantages, such as rapid, non-thermal, and stress-free machining capabilities, in past research. This review is dedicated to outline the research progress of ECJM, focusing on its fundamental concepts, material processing capabilities, technological advancements, and its variants (e.g., ultrasonic-, laser-, abrasive-, and magnetism-assisted ECJM) along with their applications. Special attention is given to the application of ECJM in the semiconductor and biomedical fields, where the demand for ultra-precision components is most pronounced. Furthermore, this review explores recent innovations in process optimization, significantly boosting machining efficiency and quality. This review not only provides a snapshot of the current status of ECJM technology, but also discusses the current challenges and possible future improvements of the technology. Full article

Heating, ventilation, and air-conditioning systems account for 40–60% of the energy consumed in commercial buildings, and much of this load originates from sub-optimal piping layouts in chiller-plant rooms. This study presents an automated routing framework that couples Building Information Modeling (BIM) with an enhanced A* search to produce collision-free, low-resistance pipelines while simultaneously guiding component selection. The algorithm embeds protective buffer zones around equipment, reserves maintenance corridors through an attention-based cost term, and prioritizes 135° elbows to cut local losses. Generated paths are exported as Industry Foundation Classes (IFC) objects for validation in a BIM digital twin, where hydraulic feedback drives iterative reselection of high-efficiency devices—including magnetic-bearing chillers, cartridge filters and tilted-disc valves—until global pressure drop and life-cycle cost are minimized. In a full-scale shopping-mall retrofit, the method significantly reduces pipeline resistance and operating costs, confirming its effectiveness and replicability for sustainable chiller-plant design. Full article

Elevators are a vital part of urban infrastructure, playing a key role in smart cities where increasing population density has driven the rise in taller buildings. As an essential means of vertical transportation, elevators have become an integral part of daily life, making their design, construction, and maintenance crucial to ensuring safety and compliance with evolving industry standards. The safety of elevator systems depends on the continuous monitoring and fault-free operation of Permanent Magnet Synchronous Motor (PMSM) drives, which are critical to their performance. Furthermore, the fault-free operation of PMSM drives reduces operating costs, increases service life, and improves reliability. The PMSM drive components may be susceptible to electrical, mechanical, and thermal faults that, if undetected, can lead to operational disruptions or safety risks. The integration of artificial intelligence and Internet of Things (IoT) technologies can enhance fault prediction, reducing downtime and improving efficiency. Ongoing challenges such as managing machine thermal load and developing more durable materials for PMSMs require the development of suitable models that are adapted to existing drive systems. The proposed framework for fault prediction is validated on a real residential elevator equipped with a PMSM drive. Multimodal signal data is processed through a Generative Adversarial Network (GAN)-enhanced Positive Unlabeled (PU) classifier and a Reinforcement Learning (RL)-based adaptive decision engine, enabling robust and scalable fault prediction in a non-intrusive fashion. Full article

The most popular interpretation of the Aharonov–Bohm (AB) effect is that the electromagnetic potential locally affects the complex phase of a charged particle’s wave function in the magnetic field free region. However, since the vector potential is a gauge-variant quantity, multiple researchers suspect that it is just a convenient tool for calculating the force field. This motivates them to explain the AB effect without using the vector potential, which inevitably leads to some sort of non-locality. This frustrating situation is shortly summarized by the statement by Aharonov et al. that the AB effect may be due to a local gauge potential or due to non-local gauge-invariant fields. In the present paper, we shall give several convincing arguments which support the viewpoint that the vector potential is not just a convenient mathematical tool with little physical entity. Despite its gauge arbitrariness, the vector potential certainly contains a gauge-invariant piece, which solely explains the observed AB phase shift. Importantly, this component has a property such that it is basically unique and cannot be eliminated by any regular gauge transformations. To complete the discussion, we also discuss the role of remaining gauge arbitrariness still contained in the entire vector potential. Full article

This paper proposes a model identification method based on the auxiliary variable closed-loop subspace identification algorithm to address the problem of modeling difficulties caused by various complex factors affecting permanent magnet brushless DC motors in practical working conditions. This method breaks through the limitations caused by the correlation between input signals and noise in traditional subspace identification algorithms. By introducing auxiliary variables, it effectively avoids the projection process, simplifies the complex calculations of principal component analysis, and improves the practicality and efficiency of the algorithm. When constructing a data-driven identification model, the actual situation of measurement data being contaminated by noise has to be fully considered. Orthogonal compensation matrices and auxiliary variables were used to construct uncorrelated terms for noise, thereby eliminating the negative impact of noise on the model’s identification accuracy. The effectiveness of the proposed identification algorithm was verified by collecting data through a chassis dynamometer simulation test of a vehicle-mounted permanent magnet brushless DC motor. The results show that compared with the traditional N4SID algorithm, the proposed closed-loop subspace identification algorithm based on auxiliary variable principal component analysis exhibits higher model identification accuracy, stronger anti-interference ability, and better stability in both noise-free and noise-contaminated conditions, providing a more reliable model basis for motor performance evaluation and control strategy design. Full article

The magnetic field of the Sun is formed by the mechanism of hydromagnetic dynamo. In this mechanism, the flow of the conducting medium (plasma) of the convective zone generates a magnetic field, and this field corrects the flow using the Lorentz force, creating feedback. An important role in dynamo is played by memory (hereditary), when a change in the current state of a physical system depends on its states in the past. Taking these effects into account may provide a more accurate description of the generation of the Sun’s magnetic field. This paper generalizes classical dynamo models by including hereditary feedback effects. The feedback parameters such as the presence or absence of delay, delay duration, and memory duration are additional degrees of freedom. This can provide more diverse dynamic modes compared to classical memoryless models. The proposed model is based on the kinematic dynamo problem, where the large-scale velocity field is predetermined. The field in the model is represented as a linear combination of two stationary predetermined modes with time-dependent amplitudes. For these amplitudes, equations are obtained based on the kinematic dynamo equations. The model includes two generators of a large-scale magnetic field. In the first, the field is generated due to large-scale flow of the medium. The second generator has a turbulent nature; in it, generation occurs due to the nonlinear interaction of small-scale pulsations of the magnetic field and velocity. Memory in the system under study is implemented in the form of feedback distributed over all past states of the system. The feedback is represented by an integral term of the type of convolution of a quadratic form of phase variables with a kernel of a fairly general form. The quadratic form models the influence of the Lorentz force. This integral term describes the turbulent generator quenching. Mathematically, this model is written with a system of integro-differential equations for amplitudes of modes. The model was applied to a real space object, namely, the solar dynamo. The model representation of the Sun’s velocity field was constructed based on helioseismological data. Free field decay modes were chosen as components of the magnetic field. The work considered cases when hereditary feedback with the system arose instantly or with a delay. The simulation results showed that the model under study reproduces dynamic modes characteristic of the solar dynamo, if there is a delay in the feedback. Full article

The instability in rare-earth material supply and rising costs have driven research into rare-earth-free electric motors. Among various alternatives, wound rotor synchronous motors (WRSMs) stand out due to their adjustable excitation, enabling high torque at low speeds, and efficient field weakening at high speeds. Unlike permanent magnet synchronous motors (PMSMs), WRSMs offer greater operational flexibility and eliminate the risk of demagnetization. However, accurately modeling WRSMs remains challenging, especially when considering axial fringing flux and leakage components, which significantly affect motor performance. To address this challenge, this paper proposes a 3D nonlinear magnetic equivalent circuit (MEC) model that explicitly incorporates axial flux components and leakage paths in WRSMs with overhang rotor structures. Unlike conventional 2D MEC models, which fail to capture axial flux interactions, the proposed approach improves prediction accuracy while significantly reducing computational costs compared to full 3D finite element analysis (FEA). The model was validated through comparisons with 3D FEA simulations and experimental back-EMF measurements, demonstrating its accuracy and computational efficiency. The results confirm that the 3D nonlinear MEC model effectively captures axial flux paths and leakage components, making it a valuable tool for WRSM design and analysis. Future research will focus on further refining the model, incorporating hysteresis loss modeling, and developing hybrid MEC–FEA simulation techniques to enhance its applicability. Full article

Background/Objectives: There is limited information on human milk (HM) microbiome composition and function in Latin America. Also, interactions between HM constituents and its microbiome have received partial attention. Objective: To characterize the HM microbiota composition considering lactation stages (colostrum, transition, and mature HM) and free glutamate concentrations in Ecuadorian mothers. Methods: We recruited 20 mothers that gave birth to normal full-term babies and donated colostrum, transition, and mature milk. Samples were assessed by 16S rRNA gene sequencing by Oxford Nanopore Technologies (ONT). Free glutamate concentrations were measured by proton nuclear magnetic resonance (NMR) spectroscopy. Results: For each lactation stage and in order of frequency, the majority of ASVs were assigned to Staphylococcus, Streptococcus, (Firmicutes); Escherichia, Acinetobacter, (Proteobacteria); Corynebacterium, Lactobacillus, Cutibacterium, (Actinobacteriota); Chryseobacterium, and Flavobacterium (Bacteroidota). Alfa diversity was similar in HM samples and tended to be higher in milk intended for male infants. We observed significant differences in qualitative β-diversity metrics between samples with low and high glutamate concentrations. Functional predictions of HM microbiota demonstrated the presence of polyamine biosynthesis II super pathway in samples with high glutamate concentrations. Conclusions: The core bacterial components of the HM microbiota in Ecuadorian women were similar to those reported from different parts of the world, with variations at the genus level. Free glutamate dynamics in HM need to be studied considering maternal production and bacterial metabolism to better understand HM composition for optimal infant nutrition. Full article

The working accuracy of space optical payloads and sensitive components carried on space aircraft greatly depends on the pointing accuracy and stability of the platform. Based on Disturbance Free Payload (DFP) technology, non-contact maglev technology is proposed in this paper, achieving dynamic and static isolation of the platform module and payload module, so that the vibration and interference of the platform module with movable and flexible components will not be transmitted to the payload module, thereby achieving the effect of vibration isolation. High-precision active control of the payload module is adopted at the same time; the platform module follows the master–slave collaborative control strategy of the payload module, meeting the requirements of high-performance payloads. A primary and backup redundant controller is designed, using a one-to-four architecture. The control board achieves high-speed and high-precision driving current control, voltage output, and outputs current feedback signal sampling. Based on uniform magnetic field design, high-precision force control performance is ensured by adjusting current accuracy. Interdisciplinary joint simulation of electric, magnetic, and structural aspects was conducted on the magnetic levitation isolation system. By conducting physical testing and calibration and designing a testing and calibration system, it has been proven that the system meets the design requirements, achieving high-precision current control technology of 0.15 mA and driving force control technology of 0.5 mN. Full article

The multi-sublattice ferrimagnet Co₂FeO₂BO₃, a prominent example of lanthanide-free magnets, was the subject of element-selective studies using X-ray magnetic circular dichroism (XMCD) observations at the L- and K- X-ray absorption edges. Research findings indicate that the distinct magnetic characteristics of Co₂FeO₂BO₃, namely its remarkable high coercivity (which surpasses 7 Tesla at low temperatures), originate from an atypical arrangement of magnetic ions in the crystal structure (sp.gr. Pbam). The antiferromagnetic nature of the Co²⁺-O-Fe³⁺ exchange interaction was confirmed by identifying the spin and orbital contributions to the total magnetization from Co (m_L = 0.27 ± 0.1 μ_B/ion and m^eff_S = 0.53 ± 0.1 μ_B/ion) and Fe (m_L = 0.05 ± 0.1 μ_B/ion and m^eff_S = 0.80 ± 0.1 μ_B/ion) ions through element-selective XMCD analysis. Additionally, the research explicitly revealed that the strong magnetic anisotropy is a result of the significant unquenched orbital magnetic moment of Co, a feature that is also present in the related compound Co₃O₂BO₃. A complex magnetic structure in Co₂FeO₂BO₃, with infinite Co²⁺O₆ layers in the bc-plane and strong antiferromagnetic coupling through Fe³⁺ ions, is suggested by element-selective hysteresis data, which revealed that Co²⁺ ions contribute both antiferromagnetic and ferromagnetic components to the total magnetization. The findings underline the suitability of Co₂FeO₂BO₃ for applications in extreme environments, such as low temperatures and high magnetic fields, where its unique magnetic topology and anisotropy can be harnessed for advanced technologies, including materials for space exploration and quantum devices. This XMCD study opens the door to the production of novel high-coercivity, lanthanide-free magnetic materials by showing that targeted substitution at specific crystallographic sites can significantly enhance the magnetic properties of such materials. Full article

We start with the 50-component relativistic matrix equation for a hypothetical spin-2 particle in the presence of external electromagnetic fields. This equation is hypothesized to describe a particle with an anomalous magnetic moment. The complete wave function consists of a two-rank symmetric tensor and a three-rank tensor that is symmetric in two indices. We apply the general method for performing the nonrelativistic approximation, which is based on the structure of the $50\times 50$ matrix ${\Gamma }^0$ of the main equation. Using the 7th-order minimal equation for the matrix ${\Gamma }^0$, we introduce three projective operators. These operators permit us to decompose the complete wave function into the sum of three parts: one large part and two smaller parts in the nonrelativistic approximation. We have found five independent large variables and 45 small ones. To simplify the task, by eliminating the variables related to the 3-rank tensor, we have derived a relativistic system of second-order equations for the 10 components related to the symmetric tensor. We then take into account the decomposition of these 10 variables into linear combinations of large and small ones. In accordance with the general method, we separate the rest energy in the wave function and specify the orders of smallness for different terms in the arising equations. Further, after performing the necessary calculations, we derive a system of five linked equations for the five large variables. This system is presented in matrix form, which has a nonrelativistic structure, where the term representing additional interaction with the external magnetic field through three spin projections is included. The multiplier before this interaction contains the basic magnetic moment and an additional term due to the anomalous magnetic moment. The latter characteristic is treated as a free parameter within the hypothesis. Full article