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Rapid and accurate detection of maritime military targets is of great significance for maintaining national defense security. Few studies have used high-resolution optical images for the detailed classification of maritime military targets. This article, inspired by EfficientDet trackers, presents a method to classify military targets on the sea from high-resolution optical remote sensing images. In the first stage, a multilayer feature extraction network is constructed to extract various features. At the same time, residual connection and dilation convolution are introduced to prevent the deep network features from disappearing. Moreover, we use multilevel attention mechanism approaches to make more effective use of multilayer features. ReLU is introduced to replace the original swish activation function to reduce the computational cost in the pretreatment stage. After this, deep feature fusion networks and prediction networks are constructed to locate and distinguish different types of ships. Different types of ships use different degrees of data expansion methods to solve the problem of sample shortage and imbalance. The multiclassification method is used to solve low classification accuracy caused by little difference between civil and military ships. Experimental results suggested that the proposed method can accurately identify multiple types of military ships.

The nonlinearity generation mechanisms in temperature compensated SAW (TC-SAW) devices arouse great interest recently. Accurate nonlinearity-simulation methods are needed eagerly to predict and further help suppress devices' nonlinearity. This paper develops the propagation theory of finite amplitude waves in nonlinear mediums. The low-frequency variable coupling terms become higher-order nonlinear physical fields' source to derive the third-order harmonic (H3) wave equation. Several important nonlinear origins are taken into full consideration including geometry and material nonlinearity. Based on the nonlinear theory, a nonlinear FEM model is set to directly calculate H3 in TC-SAW resonators without material scale factors, and the bulk mode nonlinear origin is considered with the finite thickness of the piezoelectric substrate. The model explains the periodic bulk wave characteristics of H3 are mainly caused by the nonlinear elastic effect. The amplitude of H3 increases with the thickness of metal and cover layers. Moreover, a new TC-SAW structure with small bumps above the cover layer is designed to suppress H3 response by about 12 dBm.

Sonoporation-based therapy shows great potential for clinical application. Actin cytoskeleton directly interconnects with plasma membrane and may be affected by sonoporation. This study aims to understand what the spatiotemporal dynamics of actin cytoskeleton is in the sonoporated plasma membrane. 1.5-MHz ultrasound with 13.33 µs length and 0.70 MPa peak negative pressure was applied to initiate sonoporation. It was observed the dynamics of actin cytoskeleton and plasma membrane at single-cell level. We found: 1) The dynamics of the disrupted actin cytoskeleton caused by sonoporation included three phases: expansion, contraction and resealing, and recovery. 2) The dynamics of the disrupted actin cytoskeleton was almost synchronized with that of the perforated plasma membrane in the reversibly sonoporated cells. 3) The closing time of the perforated plasma membrane was faster than the resealing time of the disrupted actin cytoskeleton in moderately sonoporated cells. These findings provide new insight in the resealing and recovery of the sonoporated cells.

The long-term fate of the reversibly sonoporated cells affect the delivery efficiency and biosafety. This study used a customized platform to perform acoustic cavitation and real-time record the cell growth and development. The reversibly sonoporated cells were categorized into mildly and moderately sonoporated ones. Compared with 85.1% division, 8.3% survival but no division and 6.6% dead in the non-sonoporated cells, for the moderately sonoporated cells, 63.4% went straight to dead, and only 9.8% completely divided into two, other 26.8% remined viable, but did not complete division. For the mildly sonoporated cells, only 16.7% lost their viability, and 68.8% could divide and proliferate normally, and other 14.6% could not divide. These results revealed that the long-term fate of the sonoporated cells was correlated with the degree of the sonoporation.

The cells will undergo repeated sonoporation by flowing microbubbles in the blood vessel. Based on a platform for performing acoustic cavitation and observing cellular responses at the single-cell level, we observed 38 sonoporated cells, all of which underwent the primary and second reversible sonoporation. Our results show that: 1) The reversibly sonoporated cells were categorized into mild and moderate sonoporation. 2) In 34 out of 38 primarily sonoporated cells, the resealing time of 18 mildly sonoporated cells was less than 16 s, which was faster than that of 16 moderately sonoporated cells. 3) In 34 out of 38 sonoporated cells, the time for membrane resealing was shorter in cells that experienced the second sonoporation compared with cells in primary sonoporation. These results provide fundamental sights into the biophysical process of sonoporation.

LEACH (Low Energy Adaptive Clustering Hierarchy) is one of the pioneer clustering routing algorithm, the idea of clustering proposed by which provides a good reference for the design of routing algorithm for wireless sensor network. In LEACH algorithm, the selection of cluster head ignores the consideration of node energy, which may lead to the death of cluster head and this will case the failure of data transmitted to sink. Besides, cluster head direct communication with the base station limits the expansion of the network scale. In response to these shortcomings, three strategies to improve the performance of LEACH-based algorithm are discussed in this paper, based on which we propose a low energy consumption high reliable multi-hop routing algorithm LEACH-MB. By improving the selection of cluster heads, introducing a mechanism of backup cluster head and adopting the approach of cluster head multi-hop, the performance of this new algorithm has been significantly improved compared to LEACH. Through the simulation analysis of the algorithm, we can find that this algorithm can prolong the network lifetime and improve the reliability of data transmission, and get a result of throughput increase.

This study is designed to find out a suitable controller to realize a uniform inertial cavitation activity of microbubbles within a physiological relevant circulation system induced by pulsed ultrasound. As microbubbles are flowing in the circulating catheter or vessel, part of which (i.e. the target region) will undergo ultrasound stimulation and scatter cavitation signals. Due to the acoustic pulses and the flowing environment, number of intact bubbles inside the system would decease with time, and expressed a steady decline trend in real-time measured inertial cavitation dose (ICD(t)). Our controller has two consecutive regulate stages, and the initial stage is designed to raise ICD(t) to the target ICD (TICD) quickly while the second stage is expected to maintain the ICD(t) within a ±10% error band, respectively. We further employed three indicators to evaluate performances of these parameters, namely the rising time (tr), the proximity ratio (e) and the normalized variability (δ). By the three indicators, we determined two ideal factors: 0.1 ×106V−1s−1for P1 and 1.5 × 106V−1s−1for P2, with them we had regulated ICD(t) for minutes and more than 82% of ICD(t) were regulated into the error band, any 7% of ICD(t) without control were in that error band. This may help in further research of target delivery or even clinical therapy.

Ultrasound-driven microbubbles can improve the sensitivity of imaging or promote macromolecules delivery. However, microbubble collapse during inertial cavitation (IC) is followed by the creation of smaller daughter bubbles, that could grow and be nuclei for acoustic cavitation. Daughter bubbles exposure to ultrasound may cause undesired bioeffects in targeted region, thus it is important to determine the properties of daughter bubbles generated by IC to achieve controllable cavitation dose during therapy. In this study, theoretical dissolution dynamics of sulfur hexafluoride bubbles was calculated firstly. Then, we applied a 1-MHz single pulse with different peak negative pressures (PNPs) and pulse lengths (PLs), and multiple 5-MHz pulses with fixed acoustic conditions to elicit IC of the preformed SonoVue microbubbles and scattering of daughter bubbles, respectively. After the IC and scattering signals were received by a 7.5-MHz transducer, time- and frequency-domain analysis was performed to obtain the IC dose and scattering intensity curve. The theoretical dissolution curves and measured scattering intensity curves were combined to determine the effect of the incident pulse parameters on the lifetime, mean radius and distribution range of daughter bubbles. Increasing the PNP reduced the lifetime and mean size of the daughter bubbles population and narrowed the size distribution. The proportion of small daughter bubbles (less than resonance size) increased with an increase in the PNP from 0.6 to 1.6 MPa. Moreover, increasing the PL caused a shift of the daughter bubbles population to the smaller bubbles with shorter lifetime and narrower distribution. The proportion of small bubbles increased from as the PL was increased from 5 to $\mathbf{100}\ \mu \mathbf{s}$ . Finally, increasing the IC dose caused a smaller mean size, shorter lifetime and narrower distribution in the daughter bubbles population. These results provide new insight into the relationship between the incident acoustic parameters and the properties of daughter bubbles.

Turning operation is one of the most widely used machining process but its machining efficiency often subjected to the chatter phenomenon. In order to suppress the chatter, this paper investigated the influence of feed speed on the chatter stability and proposed a feed speed variation method. The regenerative chatter mechanisms of two different turning operations were analyzed in detail namely orthogonal and cylindrical turning operation. The efficiency of feed speed variation was studied, the optimal control parameters for chatter suppression were proposed and the improvement of stability limit was verified by the Simulink software.

Return-Oriented Programming (ROP) is a sophisticated exploitation technique that is able to drive target applications to perform arbitrary unintended operations by constructing a gadget chain reusing existing small code sequences (gadgets) collected across the entire code space. In this paper, we propose to address ROP attacks from a different angle-shrinking available code space at runtime. We present ROPStarvation , a generic and transparent ROP countermeasure that defend against all types of ROP attacks with almost zero run-time overhead. ROPStarvation does not aim to completely stop ROP attacks, instead it attempts to significantly increase the bar by decreasing the possibility of launching a successful ROP exploit in reality. Moreover, shrinking available code space at runtime is lightweight that makes ROPStarvation practical for being deployed with high performance requirement. Results show that ROPStarvation successfully reduces the code space of target applications by 85%. With the reduced code segments, ROPStarvation decreases the probability of building a valid ROP gadget chain by 100% and 83% respectively, with the assumptions that whether the adversary knows the vulnerable applications are protected by ROPStarvation . Evaluations on the SPEC CPU2006 benchmark show that ROPStarvation introduces nearly zero (0.2% on average) run-time performance overhead.

The objective of this work is to design an optimal controller to modulate the stable cavitation activity of microbubbles induced by pulsed ultrasound. During therapy, the microbubbles inflow the target region in the blood vessel, receive ultrasound exposure and produce cavitation activities, and then outflow the therapy region. The stability of the bubbles could be affected by acoustic pulses and flowing environment, leading to the decrease of bubble number and the nonuniformly temporal distribution of stable cavitation activity in the target region. Previous researches regulated peak negative pressure (PNP) to effectively control stable cavitation activity whereas some undesirable consequences (e.g. hemorrhage) were found after applying PNP regulation. We proposed a novel proportional feedback controller based on both PNP and pulse length (PL) regulation. In order to rapidly elevate stable cavitation intensity from baseline to the pre-expected level, in our controller, a proportional factor of P 1 was firstly used to real-time adjust PNP from the initial 0.01 MPa to an appropriate level of experiential stable cavitation range. The obtained PNP was fixed in the subsequent regulation, and another factor of P 2 was used to modulate PL from the initial 20 μs to the obtained expected intensity and minimize the overshoot of the stable cavitation intensity. P 3 was then applied to keep the temporal stability of stable cavitation activity (±10% fluctuation range of the expected cavitation intensity) by further modulating PL. Finally, three parameters (rising time, stability ratio and concentration ratio) were used to evaluate the performance of the proposed method. Experimental results validated that the proposed method could control temporal distribution of stable cavitation intensity in the target region.

As a new application technology of burst control, the explosive logic network (ELN) and its functional realization play critical roles in the areas of weapon system (such as missiles and torpedoes) and aerospace, as well to determine the reliability and safety for initiating explosive devices. This paper investigates the failure models and mechanism of ELN from the perspective of failure analysis and reliability engineering, as well combine the method of performance design and analysis, which are of great significance to carry out its functional reliability evaluation and health status assessment accordingly. Firstly, taking the ELN with two-input-four-output into account, we discuss its failure modes and failure factors based on its structural and functional properties, then establish the fault tree model for qualitative analysis. Secondly, considering some uncertainties inherent in a certain size parameters, we calculate the reliability window of the gap null gate, in term of probabilistic model and quantitative method so as to obtain the reliability of the gap null gate. Meanwhile, referring to estimated accuracy, we introduced the H-Bayes method in the field of ELN system and initiating explosive devices. After that, the environmental monitoring data is applied to health assessment system for ELN. Moreover, when it comes to merging a variety of condition assessment information of ELN’s health level, we adopted the D-S evidential approach in information fusion for initiating explosive devices under shock conditions and electromagnetic interference. As far as the ELN is concerned, we find that: (1) Initiating explosive devices such as ELN are easily affected by environmental factors. The storage state described as storage life should be an important health indicator of ELN, which demands an effective evaluation strategy for the security and reliability considerations. (2) The functional reliability for complex ELN systems should be carried out by integrating multiple performance parameters into the evaluation method. (3) Along with three main indicators, namely, test information index, historical information index and monitoring information index, such information as polymorphism and relationship between quantitative and qualitative information should not be ignored.

Wireless passive surface acoustic wave (SAW) resonator has great potential in high temperature sensing applications. Nevertheless, degradation of metal electrodes and decrease of Q factors with rising temperature restrict the temperature upper limit of SAW resonators. From a structural perspective, a SAW resonator structure with grooved electrodes for interdigital transducers and groove-only grating for reflectors is proposed to improve the resonator performance at high temperatures. Quasi-3D periodic FEM models of platinum /trapezoidal-groove/langasite(0°, 22°, 30°) are established and the simulation results show that the grooved electrode is beneficial for electroacoustic coupling factor and pressure sensitivity. In addition, the groove-only grating with no metal reduces the negative effect of high temperature on resonator performance. It has been also verified by coupling-of-model theory that the spurious modes caused by structural difference can be suppressed.

The aim of this study is to illustrate the dynamics of membrane blebbing induced by acoustic cavitation, and to discuss the role of membrane blebbing in cellular recovery post-exposure. We used a customized platform for 1.5-MHz ultrasound exposure (13.33-μs duration and 0.70-MPa peak negative pressure) and recorded real-time cellular responses of Hela cells at the single cell level. Our results revealed: 1) The dynamics of reversible blebbing at the perforation site includes three phases: expansion, pausing and retraction on the time scale of tens to hundreds of seconds. 2) The bleb expansion simultaneously occurs with the membrane from perforation to resealing. 3) Actin cytoskeleton recruitment and retraction are involved in the bleb dynamics. 4) Extracellular calcium ion influx triggers membrane resealing and blebbing. These findings provide new evidence to understand cellular responses to acoustic cavitation.

The aim of this study was to investigate the response of microtubule cytoskeleton of cells to the perforated membrane by acoustic cavitation. The changes of microtubule at subcellular level were observed in real time using an experimental platform of 1.5 MHz ultrasound exposure (13.33 µs duration and 0.70 MPa peak negative pressure). HUVEC cells exhibited different degrees of cell membrane perforation under acoustic cavitation. Our results show that: 1) After acoustic perforation, tubulin simultaneously depolymerizes with cell membrane rupture. 2) In the case of small membrane damage, tubulin could be rapidly repaired with cell membrane repair. 3) In the case of large membrane damage, tubulin could be repaired far behind the membrane repair. 4) After chelating extracellular calcium ions, the cell membrane and tubulin could not be repaired. These results provide clues for exploring the mechanism of cell membrane repair by ultrasound cavitation.

Phase difference between reflectors in wireless SAW reflective delay-line sensors is commonly used to derive the measured parameters. To guarantee a wide measurement range and high accuracy, a sensing method that eliminates the 2πambiguity of phase measurement only using two reflectors is proposed. The basic principle of sensing with multi-frequency interrogation signals (MFIS) has been comprehensively analyzed. The measurement accuracy and range with the relationship of the system performance parameters are elaborated. The temperature sensing experiment using SAW reflective delay-line sensor designed on 128° YX-LiNbO 3 substrate has been carried out to verify the proposed method. The experimental results demonstrate the temperature measurement accuracy reaches $\pm 1^{\circ} \mathbf{C}$ in the range of 0~180 °C.

We measured terahertz properties of AgGaSe 2 crystal with both transmission and reflection terahertz time-domain spectroscopy. The complex refractive index of AgGaSe2 crystal is quantitatively determined based on the measurements in the transmission terahertz time-domain spectroscopy. We also demonstrate the birefringence dependence of the generated terahertz radiation from AgGaSe 2 crystal normally excited by an 800 nm Ti:sapphire laser pulse.

In global e-commerce, semantic document exchange ensures unambiguity and shares same meaning for documents sender and receiver cross different natural languages (e.g., English to Chinese), as the difference makes the translation between cross-language documents complex and inaccurate. This paper proposed a novel collaborative framework of semantic document exchange through a mediation approach which provides a sentence-based machine natural language (MNL). Here, the MNL constructs a grammatical case structure to compatible with all languages. Thus, the mediation framework enables the sentence computer-readable and understandable without ambiguity, simultaneously the MNL can improve accuracy and reduce the complexity of mapping in semantic document exchange.

The aim of this study is to investigate how the actin cytoskeleton responds to the sonoporation, and how the disturbed actin cytoskeleton restores to initial physiological status. Using a customized platform for 1.5-MHz ultrasound exposure (13.33-μs duration and 0.70-MPa peak negative pressure)and observing the dynamics of disruption and restoration of actin cytoskeleton and plasma membrane. Our results revealed: 1)The disruption and recovery of actin cytoskeleton at the sonoporation site, was temporally synchronized with the localized perforation and resealing of plasma membrane. 2)We observed the area of disruption site became larger in the first tens of seconds, then globular actin polymers directionally migrated to the disruption site along fibrous actin, accumulated and aggregated to patch the disruption site on the time scale of tens of seconds to minutes (30 s-10 min). 3)The resealing time of the disrupted actin cytoskeleton was related to the disruption degree of the sonoporaion, and actin cytoskeleton would fail to restore for irreversible sonoporation or in the absence of extracellular calcium ion. These findings provide new insight into the biological response to sonoporation.

Stable cavitation has shown great potential for clinical therapy. It is important to understand how the ultrasound pulse parameters affect the spatiotemporal distribution of stable cavitation energy. A tissue mimicking phantom for blood vessel was fabricated to comprehensively understand the effects of the pulse length (PL)and pulse repetition frequency (PRF)on stable cavitation characteristics of flowing microbubbles in the target area. A 1-MHz focused transducer and another 7.5-MHz plane transducer were employed to emit the pulsed ultrasound and receive the cavitation signal respectively. Then the signal was amplified and recorded by a high-speed AD. The following results were determined. Below the Critical PRF (CPRF), the PL had no influence on the temporal distribution of stable cavitation intensity; however, when PRF was above CPRF, the stable cavitation intensity had a uniform temporal distribution and was independent of the PRF at shorter PLs, The stable cavitation intensity correlated negatively with the PRF at longer PLs.

The aim of this study is to illustrate how lysosome exocytosis would be involved in membrane blebbing to reseal the perforated membrane by acoustic cavitation. Using a customized platform for 1.5-MHz ultrasound exposure (13.33-μs duration and 0.70-MPa peak negative pressure)and recording cellular responses of the Hela cervical cancer cell at the single cell level. Our results revealed: 1)The dynamics of blebbing at the perforation site induced by reversible sonoporation includes three phases: immediate expansion, long-time stationary, rapid retraction on the time scale of about hundreds of seconds. 2)The temporal-duration and spatial size of the bleb were positively correlated with the degree of the reversible sonoporation. 3)During the expansion of blebbing, lysosomes were delivered to the membrane surface by exocytosis, and then fused with membrane to facilitate resealing. These findings provide new evidence to reveal the resealing mechanism of the perforated membrane by acoustic cavitation.

In order to study the Doubly-Fed Induction Generator (DFIG) stator winding inter-turn short circuit fault, firstly, air-gap characteristic of magnetic field after short circuit of stator winding under inter-turn is analyzed. Secondly, the formula of the air-gap flux density, air-gap permeance, air-gap magnetic field energy and the pulsating electromagnetic force acting on the stator is obtained. Finally, the vibration characteristics of the generator stator is got. For getting the signal of stator vibration, we take stator winding inter-turn short circuit experiment by using the DFIG of dynamic emulation laboratory. By analyzing the stator vibration with Hilbert-Huang Transform (HHT) method and comparing the signal of the Hilbert spectrum, the frequency component amplitude variation with time is achieved. Comparing Marginal spectrum among different signals, the fault feature parameters of stator winding inter-turn short circuit are acquired. At last, the experimental results are in good agreement with the theoretical results.

The aim of this study is to investigate how the intracellular ROS responds to different degrees of sonoporation. Using a customized platform for 1.5-MHz ultrasound exposure (13.33-μs duration and 0.70-MPa peak negative pressure) and observing the dynamics of sonoporation and intracellular ROS at the single-cell level, we quantified the exogenous molecular uptake and intracellular ROS indicator to evaluate the degree of sonoporation and ROS change, respectively. Our results revealed : 1) Within about 100 s post-exposure, which covered intervals from membrane perforation to the completion of membrane resealing, intracellular ROS rapidly decreased because of extracellular diffusion of dichlorofluorescein through the perforated membrane, similar to the extracellular PI influx. 2) In the following 270 s (120-390 s post-exposure), ROS generation in reversibly sonoporated cells gradually increased, and was positively correlated with the degree of the sonoporation. 3) The ROS level in irreversibly sonoporated cells continuously reduced to depletion. The ROS generation in reversibly sonoporated cells may affect their long-term fate. These results provide new insight into the biological response to sonoporation.

To develop and realize the sonoporation-based therapeutic applications, it is important to understand underlying cellular bioeffects involved in the sonoporation. It is known that appropriate reactive oxygen species (ROS) is necessary to maintain normal physiological functionality, but excessive ROS would trigger downstream adverse bioeffects. However, it is still unclear about ROS response in the sonoporated cells. This study aims to investigate how the intracellular ROS responds to the perforated membrane triggered by acoustic cavitation.

Timing jitter optimization of mode-locked lasers is essential for applications that require high temporal resolution. In this work, both numerical simulation and experiments show that the Gordon-Haus timing jitter of large-net-dispersion mode-locked fiber lasers can be removed with an intra-cavity narrow band-pass filter. As a result, the filtered lasers exhibit rather low timing jitter that is immune to the net dispersion variation. Such scheme is simple and robust, which provides an alternative for long-term stabilization and timing jitter reduction of mode-locked fiber lasers.

We report on a hybrid phototransistor that consists of In 2 O 3 nanowire covered with multilayer WSe 2 . The absorption of infrared light in multilayer WSe 2 forms the accumulation of photogenerated carriers at the interface between WSe 2 and In 2 O 3 to enhance the conductance of nanowire. A responsivity of ∼104 A W−1 and an on/off ratio of ∼106 are obtained with 940 nm light irradiation at room temperature. The spectral response can be observed for photon energy near the bandgap of WSe 2 .