Coarse Adjustment Research Articles

Research on Phase Stabilization Algorithm of Femtosecond Timing System

This paper presents the design, implementation, and validation of a femtosecond timing system aimed at achieving precise time control and phase synchronization for large particle accelerators. A prototype system utilizing a continuous wave laser was developed, focusing on minimizing timing jitter and long-term phase drift. Key components include an optical delay line for coarse adjustments and a fiber stretcher for fine-tuning, achieving an adjustment precision of 1 femtosecond. The system incorporates a phase detection module with a non-In-phase/Quadrature downconversion approach, enabling high-accuracy phase measurements. A collaborative algorithm was designed to optimize the interplay between the optical delay line and the fiber stretcher, utilizing a proportional-integral-derivative (PID) control algorithm to enhance adjustment precision. A Field Programmable Gate Array (FPGA) served as the core interface converter, facilitating data communication and real-time phase information acquisition. Experimental results demonstrated significant improvements in phase stability, with average phase deviation reduced from 1374.104 fs to 15.782 fs, showcasing the effectiveness of the proposed system in achieving high precision and stability in phase control. This research provides a solid foundation for future advancements in timing systems for high-frequency reference signals.

Weather Radar Calibration Method Based on UAV-Suspended Metal Sphere.

Weather radar is an active remote sensing device used to monitor the full lifecycle changes in severe convective weather with high spatial and temporal resolution. Effective radar calibration is a crucial foundation for ensuring the high-quality application of observational data. This paper utilizes a UAV platform equipped with a high-precision RTK system and standard metal spheres to study the principles and methods of metal sphere calibration, constructing a complete calibration process and calibration accuracy evaluation metrics. Additionally, a collocated radar comparison observation experiment was conducted for cross-validation, and metal sphere calibration tests were performed on problematic radars. The experimental results indicate the following: (1) The combined application of a high-precision RTK system and a laser range camera can provide real-time position information on the metal sphere, improving the efficiency of radar target acquisition. (2) The calibration method based on UAV-suspended metal spheres can periodically conduct the quantitative calibration of Z and ZDR, achieving calibration accuracies within 0.5 dB and 0.2 dB, respectively, and supports the qualitative inspection of key parameters such as beamwidth and pulse width. (3) During field tests, a high success rate "coarse adjustment + fine adjustment + staring" sphere-finding technique was established, based on automatic switching between RHI, PPI, and FIX scanning modes. This method directs the UAV to adjust the metal sphere to the center of the radar distance bin, reducing the impact of uneven beam filling and bin crossing, ensuring the accuracy of scattering characteristic measurements.

Study and transient neutronics analysis of a 10kWth space heat pipe reactor based on a new dual protection control scheme with control annulus and movable radial reflector

This paper mainly focusses on a new dual protection control scheme based on the control annulus and movable radial reflector for a 10kWth space heat pipe reactor. Through the radial reflector, reactive coarse adjustment can be achieved, while reactive fine adjustment can be achieved through B4C control annulus. Both control schemes allow for independent control. Firstly, the steady-state neutron analysis method is conducted to evaluate the critical safety performance of different core control schemes when the reactor falls into sand or water. The first control scheme uses a movable radial reflector, which can still enable the reactor to maintain a keff below 0.85 when the reactor is soaked into the sand or water. The second control scheme uses an independent B4C control annulus, which enables the reactor to maintain a keff below 0.95 when the reactor is soaked into the sand or water. Through the dual protection control scheme, it can ensure the critical safety for the reactor when the launch or drop accident occurs. Moreover, a transient neutronics analysis is conducted to evaluate the operating characteristics and transient neutronics performance for the reactor. The results showed that compared to the control scheme of Kilopower, when the positive reactivity is introduced, the transient neutron dynamics parameters of this dual protection control scheme are superior to that of Kilopower. And it showed that the dual protection control scheme provides an improved control design for the further design and optimization of control scheme for the space reactors.

Optimized Surface Adjustment Method for Large Deployable Cable Network Antennas

Large deployable mesh reflectors typically require high surface accuracy and have large apertures. The accumulation of machining errors in a large number of cables can lead to significant deviations between the final manufactured surface and the theoretical surface, particularly due to the large number of cables involved. Adjusting the mesh reflector is often necessary to meet the surface accuracy requirements. However, traditional surface adjustment methods can be challenging to converge and time-consuming. To address this issue, our paper proposes an engineering surface based on measured manufacturing errors as a substitute for the theoretical surface. This method can save time on the coarse adjustment of surface accuracy for large deployable mesh reflectors, reducing the overall surface accuracy adjustment time by 30%.

Interactive Multi-Stage Robotic Positioner for Intra-Operative MRI-Guided Stereotactic Neurosurgery.

Magnetic resonance imaging (MRI) demonstrates clear advantages over other imaging modalities in neurosurgery with its ability to delineate critical neurovascular structures and cancerous tissue in high-resolution 3D anatomical roadmaps. However, its application has been limited to interventions performed based on static pre/post-operative imaging, where errors accrue from stereotactic frame setup, image registration, and brain shift. To leverage the powerful intra-operative functions of MRI, e.g., instrument tracking, monitoring of physiological changes and tissue temperature in MRI-guided bilateral stereotactic neurosurgery, a multi-stage robotic positioner is proposed. The system positions cannula/needle instruments using a lightweight (203g) and compact (Ø97×81mm) skull-mounted structure that fits within most standard imaging head coils. With optimized design in soft robotics, the system operates in two stages: i) manual coarse adjustment performed interactively by the surgeon (workspace of ±30°), ii) automatic fine adjustment with precise (<0.2° orientation error), responsive (1.4Hz bandwidth), and high-resolution (0.058°) soft robotic positioning. Orientation locking provides sufficient transmission stiffness (4.07N/mm) for instrument advancement. The system's clinical workflow and accuracy is validated with lab-based (<0.8mm) and MRI-based testing on skull phantoms (<1.7mm) and a cadaver subject (<2.2mm). Custom-made wireless omni-directional tracking markers facilitated robot registration under MRI.

Optimization of power feedback control system for HCN interferometer on EAST Tokamak

The Hydrogen Cyanide (HCN) interferometer stands as an indispensable diagnostic tool, designated to measure the line-integrated electron density on the Experimental Advanced Superconducting Tokamak (EAST), thereby offering essential density feedback signals for EAST operation. The HCN laser used in the interferometer is a continuous glow discharge gas laser. However, owing to variations in external ambient temperature, the HCN laser exhibits output power instability. The current power automatic feedback control system for the HCN laser interferometer exhibits low actuator adjustment precision, thereby limiting its ability to achieve maximum output power. Moreover, the system may cause a temporary power drop to zero during adjustment, while EAST operation requires the HCN laser interferometer to maintain high power continuously. In order to solve the issues, this paper developed an innovative actuator that ingeniously amalgamates the virtues of piezoelectric ceramic and stepper motor. This novel actuator, demonstrating a broad adjustment range and high precision, is intended to replace the present one in the HCN interferometer power control system. While the stepper motor executes coarse adjustment, the piezoelectric ceramic enables precise adjustment, thus enhancing the adjustment accuracy of the automatic power control system to a sub-micrometer level and an adjustment range greater than 5 mm. Accurate determination of the regulator's adjustment direction can significantly improve the efficiency of adjustment. The slope of the laser output power peak decreases as it approaches the maximum value, and increases as it moves away from the maximum value. Therefore, this system replaces the original threshold algorithm with a slope algorithm. By correctly judging the adjustment direction, the efficiency of adjustment is improved. Furthermore, this algorithm can keep the output power stable on a power peak. There will be no instances of zero power output during the adjustment, allowing the power to remain stable above the set threshold for a long time. Currently, this system has been successfully applied to the HCN interferometer, and testing has found that the system can maintain stability for at least 16 hours. Furthermore, even when the laser output power was intentionally reduced to below the set threshold, the system was able to respond quickly and adjust the output, rapidly restoring it to above the predefined threshold. Multiple tests have shown the strong robustness of the system, indicating it meets the stringent demands of the EAST's complex environment.

A Design of a Dual Delay Line DLL with Wide Input Duty Cycle Range

This article describes a dual-controller dual-delay line delay lock loop (DC-DL DLL). The proposed DLL adopted a dual delay line structure, each delay line was composed of a coarse adjustment and a fine adjustment unit, and the dual delay lines had corresponding control units to reduce the mismatch between the delay lines, and it avoided the complicated design of duty cycle correction (DCC) circuit. A frequency divider was added to divide the input clock to achieve a wider input clock duty cycle adjustment. Additionally, a simple clock synthesis circuit was proposed to synthesize the required clock. The DLL design used the 25 nm process with a voltage of 1.2 V. The simulation results showed that at a working frequency of 1.6 GHz, the peak-to-peak jitter of the DC-DL DLL after locking was approximately 17.61 ps, the maximum output duty cycle error was about 1.3%, and the input duty cycle ranged from 20% to 80%, with a power consumption of 10.06 mW.

Microwave-photonic optical fiber interferometers for wavelength interrogation of fiber Bragg grating sensors with high sensitivity and a tunable dynamic range.

We propose and demonstrate a new, to the best of our knowledge, microwave interference-based scheme with high sensitivity and tunable measurement range, which is realized by a Mach-Zehnder interferometer (MZI). A chirped fiber Bragg grating and single-mode fiber serve as the two unbalanced arms of the RF interferometer. The induced differential chromatic dispersion transfers the wavelength shift of the fiber Bragg gratings to the change of the RF phase difference between the two interferometric carriers, which ultimately leads to the variation of the RF signal intensity. The phase sensitivity can be improved by adjusting the power ratio of the two beams in the interferometer and coarse adjustment of the optical variable delay line (OVDL). The OVDL is also employed to tune the measurement range of the system by adjusting the time delay difference between the two arms of the MZI. The system effectively solves the problem of unavoidable attenuation of the sensitivity of the optical carrier-based microwave interferometry system caused by the change of phase difference due to the change of measurement parameters, avoiding the mutual constraint between the measurement range and high sensitivity.

Design of Load and Bale Density Monitoring and Control System for a Wheeled Self-Propelled Square Baler

HIGHLIGHTSA load and bale density monitoring and control system for a wheeled self-propelled square baler is proposed.A hydraulic circuit and weighing device are designed, and a bale density control model is established on this basis.The relationships among the main parameters affecting the operation of the control system are determined.The control system improved the automation and reliability of the square baler machine as a low-cost solution.Abstract. This study investigated baler load monitoring and automatic adjustment of bale density. A load monitoring and bale density adjustment system was developed for a wheeled self-propelled square baler. To realize the proposed system, a hydraulic circuit and a weighing device were designed, a bale density control program was developed, and a bale density control model was established. Bench tests were performed to obtain the relationships among the feed quantity of the baler, the load of the hydraulic cylinder on the compression chamber sidewall, the bale density, the piston’s compression force, the bale weight, and the degree of bale compression. The relationships among the operating parameters provided basic data for baler load monitoring and intelligent control of bale density. Field tests showed that when the bale density threshold was set at 5 kg m-3 and the allowable deviation was 2 kg m-3, the coarse adjustment time was less than 5 s, and the adjustment deviation of the bale density was within 5% as a whole, while most of the deviations were within 3%. The results demonstrate that the proposed control system can realize automatic adjustment of bale density according to user requirements within the allowable range. In addition, the proposed system can ensure stable operation and provide a reference for optimization and intelligent control of balers. Keywords: Bale density, Feeding load, Monitoring and control system, Square baler.

Transition metal catalyzed P–C(sp2) constructing couplings

Phosphorous compounds are one of most important class of ligands that are used in synthesis, catalysis and other processes. The coarse adjustment of electrodonative character of phosphorous can be done by switching to phosphonates or phosphinates with consecutive transformation. However fine tuning of phosphorous atom by variation of adjacent functional groups might be a serious problem due to reactivity of those. An alternative introduction of aromatic and vinylic groups can be done by P–C coupling reactions. Here I'd like to present a brief overview of published catalytic systems.

The Impact of Stimulation Intensity on Spatial Discrimination with Multi-Pad Finger Electrode

Multi-pad electrotactile stimulation can be used to provide tactile feedback in different applications. The electrotactile interface needs to be calibrated before each use, which entails adjusting the intensity to obtain clear sensations while allowing the subjects to differentiate between active pads. The present study investigated how the stimulation intensity affects the localization of sensations using a multi-pad electrode placed on a fingertip and proximal phalange. First, the sensation, localization, smearing and discomfort thresholds were determined in 11 subjects. Then, the same subjects performed a spatial discrimination test across a range of stimulation intensities. The results have shown that all thresholds were significantly different, while there was no difference in the threshold values between the pads and phalanges. Despite the subjective feeling of spreading of sensations, the success rates in spatial discrimination were not significantly different across the tested stimulation intensities. However, the performance was better for distal compared to proximal phalange. Presented results indicate that spatial discrimination is robust to changes in the stimulation intensity. Considering the lack of significant difference in the thresholds between the pads, these results imply that more coarse adjustment of stimulation amplitude (faster calibration) might be enough for practical applications of a multi-pad electrotactile interface.

Proof-of-Concept Design of an In-Line pH Neutralization System with Coarse and Fine Adjustments for the Continuous Manufacturing of Pharmaceuticals

Proof-of-Concept Design of an In-Line pH Neutralization System with Coarse and Fine Adjustments for the Continuous Manufacturing of Pharmaceuticals

Beam Formation and Vernier Steering Off of a Rough Surface.

Wavefront shaping can refocus light after it reflects from an optically rough surface. One proposed use case of this effect is in indirect imaging; if any rough surface could be turned into an illumination source, objects out of the direct line of sight could be illuminated. In this paper, we demonstrate the superior performance of a genetic algorithm compared to other iterative feedback-based wavefront shaping algorithms in achieving reflective inverse diffusion for a focal plane system. Next, the ability to control the pointing direction of the refocused beam with high precision over a narrow angular range is demonstrated, though the challenge of increasing the overall scanning range of the refocused beam remains. The method of beam steering demonstrated in this paper could act as a vernier adjustment to a coarse adjustment offered by another method.

Content-Based Visual Summarization for Image Collections.

With the surge of images in the information era, people demand an effective and accurate way to access meaningful visual information. Accordingly, effective and accurate communication of information has become indispensable. In this article, we propose a content-based approach that automatically generates a clear and informative visual summarization based on design principles and cognitive psychology to represent image collections. We first introduce a novel method to make representative and nonredundant summarizations of image collections, thereby ensuring data cleanliness and emphasizing important information. Then, we propose a tree-based algorithm with a two-step optimization strategy to generate the final layout that operates as follows: (1) an initial layout is created by constructing a tree randomly based on the grouping results of the input image set; (2) the layout is refined through a coarse adjustment in a greedy manner, followed by gradient back propagation drawing on the training procedure of neural networks. We demonstrate the usefulness and effectiveness of our method via extensive experimental results and user studies. Our visual summarization algorithm can precisely and efficiently capture the main content of image collections better than alternative methods or commercial tools.

Three-position characterization for the adjustment of MEMS accelerometer scale factor

Up/down static and the six-position least squares calibration methods are commonly used in research conducted on adjustment of the micro-electromechanical systems (MEMS) accelerometer scale factor (or sensitivity). When applying these methods, it is difficult to adjust the accelerometer measuring axis parallel to the gravity direction, causing an error in the accelerometer scale factor. In this paper, a three-position scale factor characterization that does not require corrections of the precise coincident of the measuring axis with the direction of gravity is studied. The method uses the up/down calibration method to obtain the coarse scale factor and bias. The coarse adjustment coefficient is then used to convert the accelerometer output data in the horizontal, up, and down positions into acceleration. The horizontal acceleration is used to estimate the scale factor error. Next, the estimated scale factor error is used to modify the coarse scale factor, producing a more accurate scale factor. The adjustment results from simulation and experiments on triaxial MEMS accelerometers show that the proposed method can effectively correct the scale factor error caused by inability to align the accelerometer measurement axis parallel to the gravity line, with a relative scale factor error of 0.07%, improving the accuracy of the accelerometer scale factor.

Analysis, Design, and Implementation of Junction Temperature Fluctuation Tracking Suppression Strategy for SiC MOSFETs in Wireless High-Power Transfer

In order to improve system reliability and reduce device thermal fatigue failure in multiload wireless power transfer (WPT) systems for electric vehicles, the implementation of the junction temperature fluctuation suppression strategy for SiC MOSFETs is necessary. However, current methods are relatively lacking, and active thermal management has not been used in WPT systems. In this article, the relationship between circuit parameters and junction temperature of SiC MOSFET is analyzed. In particular, a junction temperature fluctuation tracking suppression strategy for SiC MOSFETs is proposed, which consists of a coarse and a fine adjustment stage. As for the former, a shunt capacitor bank switching method is implemented. In order to compensate for the coarse adjustment defects in the small adjustment range and poor effect, in fine adjustment stage, a changing driving voltage method is used. Finally, a 5-kW multiload WPT system is built for verification. Experimental results show that the proposed strategy has obvious effect on the suppression of junction temperature fluctuation and keeps temperature near the target temperature. Benefiting from this, the maximum 13.9 °C junction temperature fluctuation is completely eliminated when the power fluctuations are within 36.1% of the rated power, and the heat load of each SiC MOSFET can be independently adjusted.

A novel MPPT method for autonomous wireless sensor networks node with thermal energy harvesting

Energy harvesting is a promising alternative to batteries for autonomous WSN nodes. Although there are various energy harvesting methods using ambient energy sources, this research is focused on thermal energy harvesting because there are abundant thermal sources in industrial sites. As only several mW can be obtained by a thermal energy harvester based on a thermoelectric generator (TEG), improvement of the energy conversion efficiency of the thermal energy harvester is essential. This paper proposes a novel maximum power point tracking (MPPT) method combining coarse adjustment and fine adjustment to enhance the energy conversion efficiency of the harvester. The Direct Adjustment (DA) method for MPPT is adopted in the coarse adjustment stage to avoid disconnecting TEG modules from conversion circuits, while an observation and self-optimization (O&SO) method for MPPT is used in the fine adjustment stage to avoid introducing perturbations and to maintain a stable output power at the maximum power point (MPP). After building up the system simulation model, a series of experiments are conducted to evaluate the proposed MPPT methods. The results show that the DA + O&SO method is an effective MPPT method for a WSN node powered by a TEG. It is able to enhance the regulation speed of the MPPT, improve the continuity of Pout, and avoid the power oscillations around the MPP.

Grain-size mineral analysis of verdete rock coarse and fine aggregates and adjustment to two granulometric distribution models

The supremacy of the mineral industry added to the necessity to supply the world market demand justifies the continuous research efforts for optimizing of the activities of mineral resource utilization. In an approach of mineral characterization, a grain-size analysis study of coarse and fine aggregates of verdete rock was presented in this work. The particle size distribution (PSD) of two samples of aggregates with granulometry &lt; 2.36 mm was experimentally obtained using sieving techniques and adjustment to Rosin-Rammler-Bennet (RRB) and Gates-Gaudin-Schuhmann (GGS) granulometric distribution models. Both RRB and GGS models regressed well to the experimental data, presenting correlation coefficient values were extremely close between them approximately 0.99. The PSD’s results indicated that 65.97% dry aggregates and 67.68% wet aggregates had a particle size with mean diameter &gt; 0.0050 mm; a similar behavior of the grain-size distributions presented by dry and wet aggregates; and a tiny presence of fine particles natural in the analyzed ore sample. The results suggested the suitability of the methodology to predict the grain-size performance the verdete ore beyond to show itself as a contribution to the enriching of the mineral characterization of the studied rock, as a potassium potential source for the mineral processing Brazilian industry.

OpenWSI: a low-cost, high-throughput whole slide imaging system via single-frame autofocusing and open-source hardware

Recent advancements in whole slide imaging (WSI) have moved pathology closer to digital practice. Existing systems require precise mechanical control, and the cost is prohibitive for most individual pathologists. Here we report a low-cost and high-throughput WSI system termed OpenWSI. The reported system is built using off-the-shelf components, including a programmable LED array, a photographic lens, and a low-cost computer numerical control (CNC) router. Different from conventional WSI platforms, our system performs real-time single-frame autofocusing using color-multiplexed illumination. For axial positioning control, we perform coarse adjustment using the CNC router and precise adjustment using the ultrasonic motor ring in the photographic lens. By using a 20X objective lens, we show that the OpenWSI system has a resolution of ∼ 0.7 µ m . It can acquire whole slide images of a 225 m m 2 region in ∼ 2 m i n s with throughput comparable to existing high-end platforms. The reported system offers a turnkey solution to transform the high-end WSI platforms into one that can be made broadly available and utilizable without loss of capacity.

Removal of unburned carbon from fly ash using enhanced gravity separation and the comparison with froth flotation

Fly ash is the by-products of electric power, which has potential application in construction industry after removing the unburned carbon. The density difference and favorable dispersion characteristics of fly ash provide the feasibility using gravity separation method. The present study had investigated the removal of unburned carbon from fly ash using enhanced gravity separation under different operation parameters such as rotational angular velocity and backwash water pressure, and the decarbonization performance was compared with the froth flotation. The results showed that both the rotational angular velocity and backwash water pressure had evident effect on the removal of unburned carbon from fly ash, and the rotational frequency adjusted more accurate relative to the coarse adjustment of backwash water pressure. The enhanced gravity separation could yield qualified Level II and Level III ash products with yield of 12%–23% and 23%–69%, while the froth flotation yield Level I, Level II and Level III ash products. The decarbonization results of enhanced gravity separation was slightly lower than froth flotation, while it provided the application value in industry without complex reagent system and high cost on the premise that met the requirements for Level II and Level III ash products.