Zr alloys are widely used as cladding materials in light-water reactors because of their low neutron absorption and excellent corrosion resistance. However, achieving high-quality diffusion bonding of Zr alloys at conventional high temperatures is challenging, where grain coarsening and formation of interfacial secondary-phase particles (SPPs) degrade joint performance and may compromise the dimensional accuracy of precision components. This study develops a low-temperature, high-strength diffusion-bonding technique for Zr-4 alloy via surface nanocrystallization, and elucidates the associated microstructural evolution and strengthening mechanisms. A gradient nanostructure (GNS) with a thickness of approximately 70 mu m was fabricated on the Zr-4 alloy surface via ultrasonic impact treatment (UIT). The GNS comprised nanograins, nanolamellae, and deformed grains, with high densities of grain boundaries, dislocations, and twins. This surface nanostructure was designed to enhance atomic diffusion, reduce bonding temperature, and improve joint properties. Diffusion-bonding experiments were performed for 30 min at temperatures ranging from 740 degrees C to 800 degrees C under a pressure of 10 MPa. The results revealed that the surface nanograins significantly accelerated interfacial void closure and suppressed SPPs overgrowth and aggregation, resulting in a more dispersed distribution of SPPs along the bonding interface. Abnormal grain growth appeared at 15-100 mu m from the bonded interface, with the largest grains reaching up to 7.2 times the size of the matrix grains. This abnormal grain growth is attributed to the uneven distribution of strain energy within the GNS, which enables some grains with energy, orientation, or size advantages to grow preferentially by continuously consuming surrounding finer grains. Fracture behavior analysis revealed that cracks initiated neither at the bonded interface nor within the abnormally large grains, but in the Zr matrix region approximately 130 mu m from the interface. These grains exhibited numerous deformation twins and acted as crack propagation barriers by coordinating deformation with the surrounding finer grains. Despite their lower yield strength, the abnormally large grains positively contributed to joint strength through a strengthening mechanism induced by hetero-deformation. The shear strength of the Zr/Zr and GNS-Zr/GNS-Zr joints improved as the bonding temperature increased. The GNS-Zr/GNS-Zr joint achieved the highest shear strength of 376.9 MPa at 800 degrees C. Under the same bonding conditions, GNS-Zr/GNS-Zr joints exhibited 1.2-1.6 times higher shear strength than the Zr/Zr joints, with greater improvements at lower temperatures.

The robust segmentation of deep-sea polymetallic nodule images is fundamental to mining-oriented resource evaluation, but complex imaging conditions and pronounced feature disparities between polymetallic nodules substantially limit the performance of segmentation models. In this paper, an adaptive enhanced dual-frequency fusion network (AEDF-Net) is proposed for deep-sea polymetallic nodule image segmentation. First, an adaptive illumination-aware fusion enhancement (AIFE) module is utilized to correct illumination and enhance contrast of input images, which dynamically improves image quality under varying degradation conditions. Subsequently, we employ a Haar wavelet decomposition (HWD) module to decompose the image into high-frequency and low-frequency components, which are processed by dual-frequency encoding paths to extract complementary boundary and structural information. A dual-frequency fusion (DFF) module is then designed to integrate features from both encoders, enabling a more comprehensive feature representation. Furthermore, a conditional skip attention gate (CSAG) module is introduced to refine cross-layer information propagation, emphasizing task-relevant feature responses. Experimental results show that AEDF-Net achieves a Dice score of 0.9469 and an Accuracy of 0.9330 on a real-world deep-sea polymetallic nodule dataset collected by the Jiaolong submersible. The superior performance of AEDF-Net demonstrate the great potential for broad applications in deep-sea mineral resource exploration and marine mining.

To address the limitations of high‐temperature diffusion bonding in zirconium alloys, the effect of controlled hydrogenation is investigated on bonding behavior, microstructure evolution, and joint performance. Zirconium alloy with 0, 200, and 2000 ppm hydrogen are prepared for diffusion bonding at 700–800 °C under 15 MPa for 30–120 min. At 200 ppm hydrogen, hydrides decomposed during bonding and reprecipitated along the interface upon cooling, eliminating interfacial voids and preserving finely dispersed second‐phase particles around equiaxed α ‐Zr grains with minimal coarsening. At 2000 ppm hydrogen, incomplete hydride decomposition resulted in residual hydrides, while β ‐Zr at grain boundaries softened the interfacial grains without extensive recrystallization, maintaining grain sizes below 7 μm. Hydrogenation lowered the required bonding temperature, where joints bonded at 700 °C with 200 ppm hydrogen achieved shear strengths of 220 MPa, comparable to un‐hydrogenated joints bonded at 750 °C. Similarly, 2000 ppm hydrogen enabled comparable strength at 720 °C to that of un‐hydrogenated joints bonded at 780 °C. Molecular dynamics simulations confirmed that hydrogen‐induced hydrogen‐vacancy clusters enhanced atomic diffusion, while finite‐element modeling demonstrated that hydrogen‐induced softening lowered local stress concentrations and promoted void closure during bonding. These multiscale insights clarify the mechanisms where hydrogen enhances diffusion bonding efficiency and joint properties in zirconium alloys.

Fault diagnosis for hydraulic manipulators plays a crucial role in ensuring operational safety but still faces challenges in fault localization. To address this issue, a guided differential dilated convolutional network (GDDCN) is proposed in this study. First, a novel interference masking mechanism is designed to provide dual guidance for feature extraction and classification. Then, a learnable differential kernel with the center parameter fixed at zero and side parameters opposite in sign is designed to adaptively extract gradient features. Afterward, a multiscale gated dilated convolution (MGDC) module is developed to capture global temporal features across multiple scales and achieve gated feature fusion. Finally, the fused features are fed into a fully connected classification module for fault classification. The results show that the GDDCN achieves diagnosis of the faulty joint with an average accuracy of 99.39

The zirconium alloy was thermo-hydrogen processed with 0.02 wt% and 0.2 wt% hydrogen, and the impact of hydrogen content on the microstructure and mechanical properties of the alloy was investigated. The hydrides in the hydrogen-treated alloys were identified as S-ZrH1.66, which exhibit a semi-coherent boundary with the alpha-Zr matrix and an orientation relationship of (0001)alpha-Zr//(111)S. The hydride platelets tend to align in lines parallel to the rolling direction (RD) and transverse direction (TD) at a slow cooling rate after thermo-hydrogenation. Thermo-hydrogen processing introduced additional intragranular secondary phases characterized as largersized ZrFe2 compared to those present in the raw alloy. The tensile strength and elongation of the zirconium alloys decrease with increasing hydrogen content due to the elevated hardness and brittleness of the hydrides. Specifically, the tensile strength decreases from 476 MPa without hydrogen to 449 MPa with 200 ppm hydrogen and 433 MPa with 2000 ppm hydrogen. The elongation of specimens without hydrogen was 38.4 %, whereas specimens with 200 ppm and 2000 ppm hydrogen exhibited reductions of 6.3 % and 42.7 %, respectively. Specimens with 2000 ppm hydrogen exhibited significantly low elongation due to the increased quantity and size of hydride lines.

Gradient nanostructured (GNS) materials have shown benefits in the diffusion bonding process; however, the occurrence of abnormal grain growth (AGG) of GNS materials at high temperatures remains insufficiently explored, particularly in relation to joint microstructure and properties. Herein, gradient nanostructures were fabricated on Zr-4 alloy plates via ultrasonic impact treatment, and subsequently utilized in diffusion bonding at 740-800 degrees C. The fabricated GNS-Zr exhibited a gradient microstructure, transitioning from surface nanograins (minimum of similar to 40 nm) to coarse-grained regions within the matrix. During diffusion bonding, the thermal instability of GNS-Zr triggered AGG, forming a novel layered bimodal structure in the bonded joints, characterized by rapidly grown nanograins (RGGs), abnormal large grains (AGs), and normally grown grains (NGs). The AGs reached up to eight times the size of the original matrix grains at 800 degrees C, allowing their orientations to dominate the overall texture. The formation of AGs was driven by the non-uniform distribution of stored strain energy in GNS-Zr, with most grain orientations inherited from the original matrix. Although AGs exhibited lower hardness and greater susceptibility to twinning, the layered bimodal structure enhanced the joint shear strength through heterogeneous deformation between AGs and surrounding finer grains. This interaction provided additional work-hardening to the smaller grains while also improving the effective strength of AGs. Consequently, AGG contributed to a significant enhancement in joint shear strength by 39.8 % at 780 degrees C and 21.8 % at 800 degrees C compared to joints bonded with as-received Zr-4. These findings highlight the essential role of AGG in determining joint properties and offer insight into the microstructural design strategies for diffusion-bonded joints.

Diffusion bonding of zirconium alloys at elevated temperatures generally results in grain coarsening and the formation of interfacial second phase particles (SPPs) in the bonded joints, which compromise joint mechanical properties. To overcome these limitations, surface nanocrystallization via ultrasonic impact treatment (UIT) was employed to refine the microstructure of Zr-4 alloy, enabling robust and reliable bonding at lower temperatures. UIT induced 40 mu m-thick gradient nanostructures (GNS) composed of nanograins, nano-lamellae, and deformed grains, enriched with grain boundaries, dislocations, and twins. Diffusion bonding experiments were carried out over a temperature range of 740 degrees C to 800 degrees C. Statistics analysis revealed that surface nanocrystallization markedly accelerated void closure and reduced both the size and fraction of SPPs while promoting a more dispersed distribution of these SPPs. Nanograins reduced the diffusion activation energy by 21 kJ/mol, as calculated from the kinetics of void closure, thereby highlighting the role of enhanced grain boundary diffusion and stored energy. A competitive relationship between void closure and SPP formation at the interface is proposed, wherein SPP formation depends on the persistence of voids while accelerated void closure restricts SPP formation by reducing nucleation sites. Consequently, elongated SPPs and voids filled with SPPs were frequently observed in Zr/Zr joints, whereas nearly circular SPPs predominated in GNS-Zr/GNS-Zr joints. Overall, the implementation of surface nanocrystallization markedly decreased interfacial voids and SPPs, achieving a peak shear strength of 376.9 MPa at 800 degrees C for GNS-Zr/GNS-Zr joints; the shear strength of these joints was approximately 1.2-1.6 times higher than that of Zr/Zr joints under identical bonding conditions, with more pronounced enhancements observed at lower bonding temperatures.

Homogenizing heat treatment is a common method utilized to eliminate inhomogeneous microstructure in cast alloys. For high-entropy alloys (HEAs), while research on this topic is valuable, there is a paucity of studies on material processes compared to studies on the strengthening mechanism. The present study employs a high-entropy alloy as a case study to homogenize its microstructure via heat treatment. Nevertheless, the findings revealed the considerable difficulty in achieving this goal. Alloy samples are homogenized in a variety of heat treatment conditions, yet the microstructure remains inhomogeneous. These findings indicate that not all high-entropy alloys can be homogenized through heat treatment. This study serves as a valuable reference for researchers engaged in the field of HEA. Further research will be necessary to propose suitable homogenization methods for the microstructure of these HEAs.

This article presents a dual-path series-capacitor (DPSC) converter with a voltage range of 9 $\sim$ 16-V input to 1-V output. By forming a capacitive-current path with flying capacitors, the proposed DPSC converter alleviates both voltage and current stresses on both the inductor and switches, enhancing overall efficiency and achieving the lowest $V\cdot A$ metric for the switches. The proposed DPSC converter enables inherent full duty cycle operation and reduced inductor current. The prototype converter demonstrates a measured peak efficiency of 94.5% with a maximum load capacity of 5 A. Besides, the proposed converter can be easily compatible with existing light-load schemes, which shows 89.2% at 0.1-A load for this design. The DPSC converter maintains high efficiency throughout the voltage conversion ratios (VCRs) and load ranges, outperforming prior state-of-the-art solutions.

To fabricate highly reliable Al cables/Cu terminals components and elucidate the microstructure evolution of the joint during ultrasonic welding, ultrasonically welded structures of 50 mm2 Al cables and 2 mm-thick copper terminals were conducted at welding energies from 1200J to 2800J and an amplitude of 54.6 μm in this paper. As the welding energy increased, the degree of plastic deformation of the Al wires gradually increased, the microstructure of the Cu side remained basically unchanged, and the effective contact area of the Cu/Al interface was gradually enlarged, enhancing the coherence between the Al wires, and the Cu-Al interfacial structure changed from an unbonded area to continuous mechanical interlocking. Parallelly, the Al grains transformed from fine serrated to equiaxed and lamellar crystals driven by geometric dynamic recrystallization (GDRX), continuous dynamic recrystallization (CDRX), and dynamic recovery (DRV), forming distinct shear textures of B/B̅{111}<110>, Rt Goss{110}<110>, Rt Cube{001}<110> and the recrystallization texture F{111}<112>, and the content of shear textures increased from 2.9% to 17.4%. In addition, the tensile shear failure load of the joint reached 2962N, which met the requirements of cable installations in the field of new energy vehicles (>1650N). Fracture analysis showed the fracture location transitioned from the Cu-Al interface to the Al-Al interface with an increase in welding energy from 1600 to 2400J. This work has theoretical guidance for the continuous promotion of vehicle light-weighting.

This paper presents a novel, compact, and energy-efficient hysteretic boost converter that employs an anti-phase AC-coupling emulate current control. The proposed scheme utilizes a two-transistor current emulator and a comparator, which allow for fast transient responses and tight closed-loop regulations. This converter was fabricated using a 180 nm CMOS process and was capable of regulating a 5 V output with a 400 mA load capacity from an input voltage range of 2.7 V to 4.5 V. The experimental results demonstrate that the proposed anti-phase AC-coupling emulate current controlling and single hysteretic comparator controlling scheme show lower power/circuit complexity and better static and transient performance. Specifically, under load transitions ranging from 0 mA to 300 mA, the converter exhibits over/undershoot voltages of 38 mV and −42 mV, respectively. Furthermore, the measured load and line regulation performances are 5 mV/A and 2.3 mV/V, respectively. Overall, this study offers a practical and efficient solution for boosting voltage levels while maintaining stable and precise regulation.

A 5-to-0.4 $\sim$ 1.2-V reconfigurable capacitive-sigma dc – dc converter with 98.4% peak efficiency is presented. By input-series and output-shunt an efficient unregulated 2:1 switched-capacitor (SC) converter with a reconfigurable hybrid Dickson Buck converter, the proposed converter achieves high efficiency for the entire output voltage and current ranges. Besides, the proposed converter also demonstrates decent regulation and transient responses. The prototype achieved 98.4% and 90.4% peak efficiency at 1.2-and 0.4-V output, respectively. The output shows a static error of 1.1 mV and under-/overshoot voltages of $-$ 23 and 23.8 mV with 0.1% settling time of 25 and 30 $\mu$ s, respectively, over 2-A load range. Compared with the prior state of the arts, the converter improves the peak efficiency by 1.5% at voltage conversion ratio (VCR) $=$ 4.2 and by 4.9% at VCR $=$ 12.5.

A novel monolithic compliant Lorentz-force-driven XY nanopositioning system (MCLNS) is designed, analyzed, and experimentally assessed with the aim of high-resolution positioning across a large workspace. A double-symmetric Lorentz-force actuator (DSLA) with the benefits of zero friction, high thrust, and large stroke is proposed to generate the actuation force. Correspondingly, a monolithic four-prismatic parallel compliant mechanism (4P-PCM) is exploited to transmit the actuation motion to the central platform and minimize the parasitic motion. The unique integration of four DSLAs and one 4P-PCM make the proposed MCLNS possess compact structure and stable performance. The characterization of the MCLNS is formulated by a specially established analytical model and validated by finite-element analysis simulation and experimental tests. Experimental studies show that the workspace of the MCLNS prototype is large than 0.87 x 0.87 mm2 and the positioning resolution of the MCLNS prototype is better than 9 nm. By means of a nonlinear forward proportional integral derivative control strategy, the maximum contouring error of the MCLNS is maintained within 2.7% while tracking a 1257 mu m s-1 circular trajectory.

This article presents a novel Dickson hybrid boost converter for thermoelectric energy harvesting that utilizes a fixed ratio switched-capacitor (SC) converter combined with a traditional switched-inductor design. This unique approach makes high conversion ratio (CR) more attainable. Besides, the converter features an on-chip LC oscillator for cold-starting the harvester without requiring any external components. To improve the efficiency of the harvester, a lookup table-based maximum power point tracking (MPPT) and a zero current detection (ZCD) circuit are also implemented. The prototype was designed and fabricated using the 55 nm low power (LP) CMOS process, with a compact 5.6- mu H inductor. Measurement results verify that the harvester can cold start at an open-circuit voltage ofV (TG) = 110mV, achieve a peak efficiency of 90.5% atV (TG) = 140mV, and maintain operation at a 5-mV input voltage with a 200-nA load. Furthermore, the converter maintains end-to-end efficiencies above 80% for a wide range ofV (TG) = 40 similar to 200mV. With a wide input range of 5 similar to 100mV and load range of 200nA similar to 4.52mA, the proposed converter represents a significant improvement in performance over previous state-of-the-art designs, with a decent power efficiency, compact form factor and wide output power range.

To obtain a robust diffusion -bonded joint at a relatively low temperature, Nb foil was applied as an interlayer to the diffusion bonding of Zr-4 alloy, and a wide process parameter involving the bonding temperature of 720-820 degrees C and holding time of 30-120 min was investigated to reveal the evolution of interfacial structure and mechanical properties of the joints. The beta-(Zr, Nb) and Widmansta center dot dter microstructure formed at the interface induced by the eutectoid transformation of the diffused Zr and Nb at the bonding temperatures over 740 degrees C. The phase structure and the thickness of beta-(Zr, Nb) layer were not considerably influenced by the increase in diffusion parameters while the Widmansta center dot dter zone thickened significantly. Moreover, the tensile strength and elongation of the resultant joints could be stabilized above 433 MPa and 7.8%, respectively, when the bonding temperature exceeded 760 degrees C with a holding time of 30 min. By extending the holding time to 60 min at 760 degrees C, the tensile strength and elongation could reach 454 MPa and 12.6%, respectively, comparable to those obtained at an elevated temperature of 820 degrees C for 30 min. Additionally, the samples fractured at the diffusion layer were characterized by the in -situ tensile test under the scanning electron microscope, and it was discovered that the crack initiation and propagation process occurred mainly between the beta-(Zr, Nb) and Widmansta center dot dter diffusion zone.

Recent advancements in liquid metal heat dissipation technology include utilizing an electromagnetic pump to induce a Lorentz force, enhancing liquid metal flow and heat dissipation. This paper introduces a full-bridge DC-DC converter for driving the electromagnetic pump. To optimize energy efficiency, particular attention is given to the analysis of output impedance and the design of a planar transformer with a minimized equivalent series impedance. Comprehensive simulations and experiments are conducted to validate the system's performance. A 5 V input voltage 2.5~13.75 mV output voltage FB DC-DC converter with 0.25 mΩ load resistance is demonstrated. The maximum conversion ratio is 2000.

Searchable symmetric encryption (SSE) has recently been under the spotlight in a cloud data storage system due to its high efficiency. SSE allows a client to outsource his private data while maintaining data searchability. To ensure the correctness of query results, verifiable SSE has attracted a lot of attention from both academia and industry to enable reliable encrypted search over the untrusted cloud server. However, most traditional verifiable SSE schemes focus on point queries instead of range queries. Moreover, no effective countermeasures are available to prevent clients from maliciously rejecting the correct result for denying the payment. In this paper, we take the first step to study verifiable range queries with fairness and forward security. First, to support efficient range query over numerical values, we propose Prefix Tree-like Keyword Set (PTKS), a novel data structure to largely reduce the number of search tokens. Specifically, the number of search tokens is up to a logarithmic value (e.g., 7) of the query range width (e.g., [0, 1000]) with PTKS. Then, we propose a double-layer verification mechanism including client-side verification and on-chain verification via the smart contract on the blockchain to achieve cost-effective fair verification. In addition, our range query scheme supports forward-secure update operations. Based on these, we propose a blockchain-based verifiable, fair and forward-secure range query scheme. Finally, extensive experiments demonstrate the efficiency of our scheme.

This paper presents a hybrid boost converter with a high voltage conversion ratio (VCR) up to 14.4x for LED-Lighting applications. By utilizing two inductors and flying capacitors, the proposed converter surpasses VCR of the conventional boost topology by threefold, thereby simplifying controller design. Moreover, the reduced voltage stresses enable the utilization of low voltage power switches, leading to improved power efficiency. Furthermore, higher switching frequency and lower switching node voltages contribute to a reduction in inductor volumes, enabling higher power density. Designed and simulated in a 180 nm Bipolar-CMOS-DMOS (BCD) process, the proposed converter can generate a 15 $\sim$ 36-V output from a 2.5-5-V Li-ion battery, capable of delivering a maximum load of 150 mA. Simulation results demonstrate peak efficiencies of 94.3% and 89.6% at VCR values of 6 and 14.4, respectively.

The complicated topographies of the deep sea pose significant challenges for the core drilling with the Jiaolong submersible manipulator. To address this problem, we proposed a core-drilling kinematic model and evaluated the core-drilling behavior of the submersible manipulator by comprehensively considering the uncertain posture of the Jiaolong submersible. First, we established a forward kinematic model for the core-drilling task in deep sea, which satisfied the requirement of gravitational-direction core drilling. Based on the forward kinematic equations, we then built a double-redundancy inverse kinematic model, which was able to determine the required motion trajectories of six active joints according to the desired core-drilling trajectory. The core-drilling workspaces and the motions of the Jiaolong submersible manipulator were assessed with several calculation examples. The established forward and inverse kinematic models are constructed with clear analytic equations, and thus are directly applicable to the Jiaolong submersible manipulator-based core-drilling task.

As the power demand of computing cores grows explosively, large conversion ratio, high efficiency and compact 12V-to-1V DC-DC converters become increasingly important. Double step-down (DSD) converters [1]–[2], also known as series-capacitor converters, offer a promising solution using the capacitors to reduce the high voltage stress and to extend the duty cycles, however, at the cost of multiple inductors and limited duty cycle range (D $<$ 50%). To break the duty cycle limit, some previous work employs extra power switches or capacitor cross-connected (CCC) design for D>50% operation during a short transient period [3]–[4]. The steady-state operation, however, is still not allowed and limits the transient response and output voltage range. Besides, DSD converters suffer from limited efficiency since the switch voltage stress is still high. To quantify the switch losses of the DSD and the proposed work, the popular V.A metric is adopted here [5], which identifies the overall converter conduction and switching losses with the lower V.A value indicating lower losses. In this work, we propose a dual-path series-capacitor converter which shows inherent full duty cycle range, low V.A metric and excellent efficiency even with only one inductor. Compared with the conventional DSD converters, the capacitors in this work not only reduces the switch voltage stress, but also form a capacitive current path. Therefore, both the switch voltage and the current stresses are alleviated, leading to competitive converter V.A metric and efficiency over wide output voltage and load ranges. In addition, the capacitor charge balance is easily achieved and, hence, inherent full duty cycle operation is obtained.