•Fatigue of 304L stainless steel was investigated with dynamic mechanical analysis.•A peak of damping related prior fatigue stress amplitude and time was found.•Fatigue history and residual life may ...be evaluated from damping curves.
The amplitude-dependent damping of 304L austenitic stainless steel with prior fatigue loading is investigated using dynamic mechanical analysis (DMA). The results show the damping curves of the steel samples are associated with the prior fatigue state. There is a peak in the damping curve when the strain amplitude is over 0.1% and the peak value increases with the prior fatigue stress amplitude and cycle number. The high sensitivity of damping peak to the prior fatigue may imply a new method to evaluate the fatigue history of austenitic stainless steel.
•FAC experiment at same working condition as NPP secondary pipe materials.•Wall thinning rate measurement using high precision ultrasonic.•Wall thinning rate of materials with different chromium ...content.
Wall thinning rate is an important issue during design of CAP1400 nuclear power plant (NPP) secondary loop. A single-phase flow accelerated corrosion (FAC) test loop was established to simulate the typical working condition of the secondary loop. The wall thinning rate of A335P11 and 20# steel elbow was measured using high precision ultrasonic sensor on the test loop. The results show that elbow part has higher thinning rate than that at straight part, especially at intrados of elbow. Wall thinning rate of 20# steel elbow is about three to four times of that A335P11 steel because of the high contents of Chromium at A335P11. According to the FAC test results it shows that A335P11 could be one of the preferred pipe material of CAP1400 secondary loop.
In this research, the mechanical behavior of a multi-pass nickel-aluminum bronze alloy weld joint is investigated. Macro-tensile testing shows the mechanical behavior difference of the weld and base ...materials. Micro indentation data is applied to calculate the local mechanical properties in a multi-pass weld and base materials. The indentation loading-unloading cycle and stress-strain calculation model are introduced in the paper. It shows that the micro indentation results are in good agreement with the macro-tensile test data. Both the micro structure and uncertainties within the analysis model affect the discrepancy of two testing methods.
Vibratory stress relief (VSR) has been used in China for 25 years. The relevant code of practice on VSR is finished and has been released recently. Residual stress is an important problem during ...manufacturing welded structures, especially for huge structures, as the heat treatment process is impractical for huge structures. VSR is a simple and practical method to reduce the residual stress of welded structure and maintain the structure's dimension stability. This paper introduces the recent application and research of welded structures VSR in China. The VSR of carbon steel and stainless steel structures, such as the structure in huge hoist machine, the rail of maglev train system and structure of HT-7U Tokamak, are discussed. The effectiveness evaluation of VSR processing is described and a new method of evaluation using dynamic stress is discussed.
Vibratory stress relief (VSR) has been used in China for 25 years. The relevant code of practice on VSR is finished and has been released recently. Residual stress is an important problem during ...manufacturing welded structures, especially for huge structures, as the heat treatment process is impractical for huge structures. VSR is a simple and practical method to reduce the residual stress of welded structure and maintain the structure's dimension stability. This paper introduces the recent application and research of welded structures VSR in China. The VSR of carbon steel and stainless steel structures, such as the structure in huge hoist machine, the rail of maglev train system and structure of HT-7U Tokamak, are discussed. The effectiveness evaluation of VSR processing is described and a new method of evaluation using dynamic stress is discussed.
In social aware networks, the routing protocol possesses a considerable amount of sensitive user information during node transmission. When selecting the next hop node for transmitting information in ...social sensing networks, there is an inherent risk of privacy breach due to malicious nodes attacking innocent nodes within the network. To address the issue of user privacy leakage, this study presents a novel privacy-preserving access control algorithm, termed
Attribute Trust-based Security
(ATST), which is designed to protect sensitive information. The algorithm, based on encrypting the plaintext message to ensure message security, employs the user’s attributes to create an attribute trust measurement model and a network access control structure. This process identifies a trusted next hop node for information transmission. Subsequently, the access control tree model derived from the attribute is utilized during decryption. After the message reached its destination node, only the user who satisfied the access control criteria of the decryption module was authorized to decrypt the ciphertext. By verifying the trust measurement and access control of nodes through the dual trust mechanism, it prevented malicious nodes from entering the network, causing damage to the network and affecting the performance of the network. In addition, the clear text message was encrypted and transmitted, and the final receiving node was verified to ensure the secure transmission of the message to the destination node. The simulation outcomes demonstrate that the ATST algorithm effectively mitigates the effects of malevolent nodes on the network, ensuring message transfer efficiency and reducing the average delay.
While rodent models are vital for studying mental disorders, the underestimation of construct validity of fear indicators has led to limitations in translating to effective clinical treatments. ...Addressing this gap, we systematically reviewed 5054 articles from the 1960 s, understanding underlying theoretical advancement, and selected 68 articles with at least two fear indicators for a three-level meta-analysis. We hypothesized correlations between different indicators would elucidate similar functions, while magnitude differences could reveal distinct neural or behavioral mechanisms. Our findings reveal a shift towards using freezing behavior as the primary fear indicator in rodent models, and strong, moderate, and weak correlations between freezing and conditioned suppression ratios, 22-kHz ultrasonic vocalizations, and autonomic nervous system responses, respectively. Using freezing as a reference, moderator analysis shows treatment types and fear stages significantly influenced differences in magnitudes between two indicators. Our analysis supports a two-system model of fear in rodents, where objective and subjective fears could operate on a threshold-based mechanism.
•Reviewed 5054 articles, revealing theoretical shifts in fear indicators.•68-article meta-analysis shows varied correlations among fear measures.•Challenges freezing as sole fear metric, urges multi-dimensional view.•Supports two-system fear model, separating observable and subjective responses.•Proposes threshold mechanism differentiating defensive and cognitive fear.
In socially aware networking, encryption algorithms are used in privacy-preserving algorithms to provide security for the nodes. However, the shared key lacks certain security management during ...transmission, which can affect the security of messages delivery. Therefore, this paper proposes a
Self-organizing Key Security Management Algorithm
(SKSM) to manage the secure transmission of keys used in encryption algorithms in socially aware networking. The key management algorithm comprises three main parts: node authentication protocol, node trust management, and key slice transmission. Firstly, zero-knowledge authentication and trust management are utilized to authenticate and manage the network nodes. Then, threshold cryptographic segmentation of keys is performed for transmission. After the key reaches the threshold, the key is recovered to ensure that the encrypted information will not be leaked or intercepted during transmission. The simulation experimental results demonstrate that the SKSM algorithm, compared with the traditional algorithms more effective than the traditional algorithm in ensuring secure message transmission, improving transmission rates, and reducing average network transmission latency.
A high-performance towing cable hydrophone array based on an improved ultra-sensitive fiber-optic distributed acoustic sensing system (uDAS) with picostrain sensitivity is demonstrated and tested in ...sea trial, for the first time. A new composite transducer is designed and optimized to enhance the acoustic pressure sensitivity significantly. A sea trial is carried out to test the performances of such a hydrophone array, including flow noise, underwater acoustic signal capture capacity, beamforming processing and localization of artificial source targets. The array exhibits high sensitivity and low noise floor. An average sensitivity of −129.23 dB re rad/µPa at frequencies from 10 Hz to 1500 Hz has been achieved. The localization at distances of 5 km and 10 km is realized, respectively, validating the excellent remote detection and positioning capability of the hydrophone system. The proposed towing cable system, with high sensitivity, simple structure and remote target localization ability, may pave a way for development of the next generation of high-performance light-weighting hydrophone arrays for towing applications.
With the development of imaging technology and computer-assisted surgery in oral and maxillofacial surgery, digital technology is widely used in vascularized bone flap grafts for mandibular ...reconstruction. The aim of this study was to use digital technology throughout the treatment process to show that digital techniques can provide a reliable and accurate match between the mandible and the iliac crest flap to achieve functional reconstruction of mandibular segment defects.
Twenty patients underwent 3-dimensional (3D) computed tomography (CT), mirroring technology, 3D model prototyping, and CT angiography (CTA) for treatment planning. Individual preformed reconstruction plates were fabricated and iliac crest flaps were designed preoperatively. After complete resection of the mandibular lesion, the iliac crest flap was shaped to reconstruct the mandibular defects.
During follow-up (range, 12 to 36 months), the facial shape, facial symmetry, and mouth opening of all patients recovered well. The 3D CT reconstruction also was evaluated for height, width, length, and bone healing of the iliac crest flap. Postoperative examination showed ideal bone union between the iliac crest flap and the mandible at 6 months. Nine patients received implant-supported fixed dentures to restore dentition. After follow-up, all patients were satisfied with their facial esthetics and function. The new mandible provided a suitable 3D position for implant-supported fixed partial dentures.
Use of digital techniques throughout the course of treatment improves the predictability and convenience of functional mandibular reconstruction. Individual preformed reconstruction plates and CTA effectively guaranteed the accuracy of iliac flap preparation.
