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The shrinkage of core concrete during construction is the key reason for the separation of steel pipes and core concrete. Utilizing expansive agents during cement hydration is one of the main techniques to prevent voids between steel pipes and core concrete and increase the structural stability of concrete-filled steel tubes. The expansion and hydration properties of CaO, MgO, and CaO + MgO composite expansive agents in C60 concrete under variable temperature conditions were investigated. The effects of the calcium–magnesium ratio and magnesium oxide activity on deformation are the main parameters to consider when designing composite expansive agents. The results showed that the expansion effect of CaO expansive agents was predominant in the heating stage (from 20.0 °C to 72.0 °C at 3 °C/h), while there was no expansion in the cooling stage (from 72.0 °C to 30.0 °C at 3 °C/d, and then to 20.0 °C at 0.7 °C/h); the expansion deformation in the cooling stage was mainly caused by the MgO expansive agent. With the increase in the active reaction time of MgO, the hydration of MgO in the heating stage of concrete decreased, and the expansion of MgO in the cooling stage increased. During the cooling stage, 120 s MgO and 220 s MgO resulted in continuous expansion, and the expansion curve did not converge, while 65 s MgO reacted with water to form brucite in large amounts, leading to its lower expansion deformation during the later cooling process. In summary, the CaO and 220 s MgO composite expansive agent in the appropriate dosage is suitable for compensating for the shrinkage of concrete in the case of a fast high-temperature rise and slow cooling rate. This work will guide the application of different types of CaO-MgO composite expansive agents in concrete-filled steel tube structures under harsh environmental conditions.

The exponential growth of data generated from increasing smart meters and smart appliances brings about huge potentials for more efficient energy production, pricing, and personalized energy services in smart grids. However, it also causes severe concerns due to improper use of individuals’ private data, as well as the lack of transparency and auditability for data usage. To bridge this gap, in this article, we propose a secure and auditable private data sharing (SPDS) scheme under data processing-as-a-service mode in smart grid. Specifically, we first present a novel blockchain-based framework for trust-free private data computation and data usage tracking, where smart contracts are employed to specify fine-grained data usage policies (i.e., who can access what kinds of data, for what purposes, at what price) while the distributed ledgers keep an immutable and transparent record of data usage. A trusted execution environment based off-chain smart contract execution mechanism is exploited as well to process confidential user datasets and relieve the computation overhead in blockchain systems. A two-phase atomic delivery protocol is designed to ensure the atomicity of data transactions in computing result release and payment. Furthermore, based on contract theory, the optimal contracts are designed under information asymmetry to stimulate user's participation and high-quality data sharing while optimizing the payoff of the energy service provider. Extensive simulation results demonstrate that the proposed SPDS can effectively improve the payoffs of participants, compared with conventional schemes.

The principle of computational ghost imaging (GI) offers a potential application in optical encryption. Nevertheless, large numbers of keys composed of random or specific patterns set an obstacle to its application. Here, we propose a series of pattern compression methods based on computational GI, in which thousands of patterns are replaced by a single standard image (i.e., two-dimensional data), a sequence of numbers (i.e., one-dimensional data) or the fractional part of an irrational number (i.e., zero-dimensional data). Different pattern compression methods are tested in both simulations and experiments, and their error tolerances in encryption are further discussed. Our proposed methods can greatly reduce the pattern amount and enhance encryption security, which pushes forward the application of computational GI, especially in optical encryption.

In last 15 years, n-type doped selective epitaxy in source and drain (S/D) for nMOS have been heavily investigated. Initial interests for nMOS S/D epitaxy were focused on carbon and phosphorus doped Si:CP film for channel strain engineering and was adapted in production. In 2012, another type of ultrahigh phosphorus doped Si:P was proposed as a replacement for Si:CP for tensile engineering. With as high as 4.5E21 doping level, such Si:P film showed comparable strain as Si:CP with 2% substitutional carbon, but with much simpler process design and quickly accepted by the industry. These ultra-high doped Si:P film also promoted interests in the mechanism for such high doping level and high strain level. In last couple years, phosphorus vacancy complexes, particularly P4V, or pseudo-cubic Si3P4, is widely accepted as the key mechanism. Although still under debate, formation of high concentration, phosphorus stabilized vacancy, up to 1E21 or 2%, is also believed to be responsible for the observed high strain. Along the same line, it was quickly discovered that ultrahigh arsenic or antimony doped films are also possible (Fig 1). And high strain Si:As is also observed with a similar strain level as Si:P, with even higher doping level, likely due to the formation of As4V complex. A group V and vacancy complex, V4V complex, is electrically neutral therefore would not contribute to carrier activation. V4V interaction with carrier would be essential to understand activation and deactivation in ultrahigh n-type doped epitaxy film. P-V interaction have been observed in early studies of bipolar device or solar device. It is also extensively studied in late 1990s to understand the USJ formation and activation. To compare with these typically implanted and annealed or diffused data, high doped Si:P and Si:As epitaxy films were deposited at different temperature and annealed with different thermal budget. Our data showed that selective Si:P as grown resistivity v.s. deposition temperature closely follow the equilibrium model based on literatures, indicating selective Si:P film as grown being near thermal equilibrium from active carrier point of view, despite one order magnitude higher P concentration (Fig.2). Selective Si:As, however, showed a different trend, with lower deposition temperature having lower resistivity. To understand the mechanism, non-selective Si:P with fast deposition rate was deposited and then annealed at deposition temperature for different time. it reveals that with fast deposition rate, initial film is activated well beyond thermal equilibrium. But it quickly deactivated within 90sec to near thermal solubility (Fig 3.). Si:As is deactivated at a much slower rate and lead to a different as grown resistivity trend. The energy favored V4V structure requires a minimum temperature to dissolve and activate the carrier. 800C is found not sufficient for Si:P and Si:As requires even higher temperature and thermal budget. To investigate the activation and deactivation, HRXRD and 4-point probe were used to study the strain and carrier concentration evolution during activation and deactivation. Unlike Si:As that always observed higher strain during deactivation from HRXRD, Si:P seems to have multiple paths for deactivation. It is found that depending on active carrier history; for example, low temperature deactivation of active carrier from random capture during epitaxy growth could involve more P4V formation therefore associated with a strain gain (Fig. 3); while for carriers gained from millisecond laser high temperature anneal, post spike annealing sometime involves strain loss during deactivation, possibly via significant interstitial P, on top formation of P4V. P4V formation during deactivation provides a model for transient diffusion enhancement in Si:P with some anneal conditions. As shown in Fig 4, only over-activated sample showed enhanced tail diffusion during 900C spike anneal, probably due to P4V silicon interstitial kick-out effect. To further investigate Si:P activation and deactivation, differential Hall effect measurement (DHEM) was used to obtain the carrier depth profile of different samples. As shown in Fig 5, 1.5E21 to 3E21 total doping level, there is minimum effect of on carrier concentration. One distinct feature on the data is the carrier degradation toward surface. It is possible during the film cool down post deposition, the surface deactivated faster, assisted from the surface flux of interstitial or vacancy. Understand the surface effect on Si:P and Si:As activation deactivation is essential to improve the contact resistance for future nodes. Figure 1

Since the paradigm shift in 2009 from pseudo-thermal ghost imaging (GI) to computational GI using a spatial light modulator, computational GI has enabled image formation via a single-pixel detector and thus has a cost-effective advantage in some unconventional wave bands. In this Letter, we propose an analogical paradigm known as computational holographic ghost diffraction (CH-GD) to shift ghost diffraction (GD) from classical to computational by using self-interferometer-assisted measurement of field correlation functions rather than intensity correlation functions. More than simply “seeing” the diffraction pattern of an unknown complex volume object with single-point detectors, CH-GD can retrieve the diffracted light field’s complex amplitude and can thus digitally refocus to any depth in the optical link. Moreover, CH-GD has the potential to obtain the multimodal information including intensity, phase, depth, polarization, and/or color in a more compact and lensless manner.

Quantum-illumination-inspired single-pixel imaging (QII-SPI) or computational ghost imaging protocol is proposed to improve image quality in the presence of strong background and stray light. According to the reversibility of the optical path, a digital micro-mirror device acts as a structured light modulator and a spatial light filter simultaneously, which can effectively eliminate 50% of stray light. Accompanied by a 6 dB gain of detection signal-to-noise ratio under an equivalent loss condition, our scheme only requires a simple and minor modification on the placement of the single-pixel detector based on the original SPI system. Since QII-SPI will obtain almost the same reconstruction results as the passive SPI technology in principle, one can, therefore, adjust the placement position of the detector, without exchanging the relative position of the detector and the light source to realize the flexible conversion of the SPI system from active to passive. Also, this work initially discusses the influence of relative coherence time on Hadamard-based SPI driven by a thermal source. This work brings new insights into the optical path design of the SPI technology, paving the way for the practical application of active SPI in stray light environments.

How can a target's differential image of multiple components at a certain degree of freedom (DOF) of light (e.g., wavelength, polarization, and position) be obtained? Previous schemes often need two steps, i.e., first collecting each component of the target simultaneously with multiple detectors or sequentially with a single detector, then performing the difference operation in the digital postprocessing. Based on the principle of computational ghost imaging (GI), we here take advantage of the natural complementarity in space to design an illumination mode, which is no longer the spatiotemporal fluctuation of photon number (light intensity) but the photons with different components under the same DOF. By applying this engineered illumination to computational GI, termed ghost difference imaging (GDI), we can achieve differential imaging of multiple components of a certain DOF in a single-round acquisition using only one single-pixel detector with no extra digital-subtraction operations but higher SNR. Both multiwavelength-difference GDI and position-difference GDI are well demonstrated in simulations and experiments. Further, the GDI scheme reduces the number of sampling times for differential imaging while also increasing photons' utilization. Our work, therefore, provides an insight for GI modality, along with a straightforward and low-cost update of the light path, which is suitable for all computational GI systems using the digital micromirror device.

Gestalt psychology puts forward the laws of similarity, proximity and common destiny. These laws all point out that visual stimuli work together to form a similar pattern organization, which results in the visual elements conforming to the same rules to be regarded as a group by the observer. However, the attributes of visual elements are now more diverse, including the dynamic changes of visual elements. In this paper, based on Bertin’s five visual variables, we will explore the impact of the coordinated changes of these visual variables on human visual perception. The experiment produced the ranking of visual variables on the strength of grouping ability. In practical application, the relative grouping strength of these visual elements has high application value for interface design and data visualization research.

Computational ghost imaging (CGI) can reconstruct the pixelated image of a target without lenses and image sensors. In almost all spatial CGI systems using various patterns reported in the past, people often only focus on the distribution of patterns in the spatial dimension but ignore the possibility of encoding in the time dimension or even the space-time dimension. Although the random illumination pattern in CGI always brings some inevitable background noise to the recovered image, it has considerable advantages in optical encryption, authentication, and watermarking technologies. In this paper, we focus on stimulating the potential of random lighting patterns in the space-time dimension for embedding large amounts of information. Inspired by binary CGI and second-order correlation operations, we design two novel generation schemes of pseudo-random patterns for information embedding that are suitable for different scenarios. Specifically, we embed a total of 10,000 ghost images (64 × 64 pixels) of the designed Hadamard-matrix-based data container patterns in the framework of CGI, and these ghost images can be quantitatively decoded to two 8-bit standard grayscale images, with a total data volume of 1, 280, 000 bits. Our scheme has good noise resistance and a low symbol error rate. One can design the number of lighting patterns and the information capacity of the design patterns according to the trade-off between accuracy and efficiency. Our scheme, therefore, paves the way for CGI using random lighting patterns to embed large amounts of information and provides new insights into CGI-based encryption, authentication, and watermarking technologies.

Improving the reliability of the Power Communication Network (PCN) has become an important research content. It is known that the existing algorithm analyzes the characteristics of the network from the dimension of the network topology, ignoring the alternative association characteristics between the network nodes, resulting in low reliability of the PCN. In order to solve this problem, this paper first analyzes the characteristics of network resource association from three aspects: resource characteristics, resource performance association analysis and resource fault correlation analysis. Then, the reliability analysis and optimization algorithm of PCN based on resource association features is proposed. Through simulation experiments, it is verified that the proposed algorithm effectively improves the reliability of the PCN.

A new method is proposed to improve the signal-to-noise ratio (SNR) of regions of interest (ROIs) in a ghost imaging (GI) system with uneven speckle illumination. The imaging results in a GI system can be distorted when there is an uneven distribution of light. In this study, three thin-film polarizers are used to create illumination patterns in uneven light intensity distribution. In particular, the polarizer set is loaded on the object arm only, that is, the original uniformly distributed light field is still acquired by the reference arm. This small change in the light path eliminates the distortion caused by uneven illumination while increasing the SNR of the ROI. This strategy has been confirmed in principle and through simulation and experiments.

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This study proposes two methods of optical watermarking based on multiplexed time-varying signals for computational ghost imaging using the Hadamard matrices. The proposed methods can realize image fusion and dual optical encryption. The time-varying signal is encoded into a specific Hadamard coefficient in advance and hidden in the light source of the transmitting end as a multiplicative factor or loaded at the receiving end as an additive factor. Theory and experiments confirm the feasibility of this scheme. Moreover, the scheme is highly scalable and has potential applications in multispectral single-pixel imaging.

Since Hanbury Brown and Twiss revealed the photon bunching effect of a thermal light source in 1956, almost all studies in correlation optics have been based on light’s intensity fluctuation, regardless of fact that the polarization fluctuation is a basic attribute of natural light. In this work, we uncover the veil of the polarization fluctuation and corresponding photon correlations by proposing a new light source model, termed pseudo-natural light, embodying both intensity and polarization fluctuations. Unexpectedly, the strong antibunching and superbunching effects can be simultaneously realized in such a new source, whose second-order correlation coefficient g ( 2 ) can be continuously modulated across 1. For the symmetric Bernoulli distribution of the polarization fluctuation, particularly, g ( 2 ) can be in principle from 0 to unlimitedly large. In pseudo-natural light, while the bunching effects of both intensity and polarization fluctuations enhance the bunching to superbunching photon correlation, the antibunching correlation of the polarization fluctuation can also be extracted through the procedure of division operation in the experiment. The antibunching effect and the combination with the bunching one will arouse new applications in quantum imaging. As heuristic examples, we carry out high-quality positive or negative ghost imaging, and devise high-efficiency polarization-sensitive and edge-enhanced imaging. This work, therefore, sheds light on the development of multiple and broad correlation functions for natural light.

A simple chemical precipitation method is used to synthesize the cubic phase of ZnS nanoparticles. The crystal structure, phase purity, surface morphology, optical and photo-luminescence properties, and photocatalytic activity of ZnS nanoparticles were studied using X-ray diffraction (XRD), fourier transform infrared (FTIR) spectra, Raman spectrometer, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), UV–vis spectrophotometer, fluorescence spectrophotometer and 721 spectrophotometer. XRD, FTIR, Raman and XPS analysis indicates that the ZnS nanoparticles has a cubic phase with the cell parameter a = 5.406 A without the presence of any other impurities. SEM image shows that the average particle size of ZnS nanoparticles is about 40 nm. Optical properties and photoluminescence experiment confirmed that the Eg value is found to be 3.21 eV and the emission spectra are made up of four emission bands at 345, 408, 444 and 510 nm under excitation wavelength at 290 nm. Photocatalytic experiment results indicate that the pure ZnS nanoparticles exhibits an obviously enhanced photocatalytic activity for degradation MO, and MR dyes than degradation MB, and XO dyes due to the ZnS nanoparticles can easily degradation the N N bonds. Based on the electrochemical measurement and photocatalytic experiment, a possible photocatalytic mechanism for degradation of various dyes in presence of the ZnS nanoparticles are analyzed.

With the arrival of the 5th generation mobile networks (5 G) era, the data needed by mobile devices (MDs) is explosively growing. High-consumption, low-latency applications are huge challenges for resource-constrained Internet of things (IoT) devices. Mobile edge computing overcomes the limitations of computing resources on MDs by offloading tasks generated by MDs and assigning them to nearby MEC servers. Therefore, mobile edge computing (MEC) becomes important. This paper presents a task offloading strategy for the multi-device multi-server system. To meet the task requirements of different MDs, we formulate an overhead minimization problem to optimize the delay and energy consumption of the system. We propose the Double Deep Q Network (Double-DQN) algorithm to perform location selection strategies for tasks generated on the mobile devices and allocate respective computing resources. Simulation results show that the algorithm can allocate resources reasonably and reduce the overhead of the entire system.

Computational ghost imaging or single-pixel imaging enables the image formation of an unknown scene using a lens-free photodetector. In this Letter, we present a computational panoramic ghost imaging system that can achieve a full-color panorama using a single-pixel photodetector, where a convex mirror performs the optical transformation of the engineered Hadamard-based circular illumination pattern from unidirectionally to omnidirectionally. To our best knowledge, it is the first time to propose the concept of ghost panoramas and realize preliminary experimentations. It is foreseeable that ghost panoramas will have more advantages in imaging and detection in many extreme conditions (e.g., scattering/turbulence and unconventional spectra), as well as broad application prospects.

Single-pixel imaging, which is also known as computational ghost imaging, can reconstruct an entire image using one non-spatially resolved detector. However, it often requires a large amount of sampling, severely limiting its application. In this paper, we discuss the implementation of secured regions of interest (SROIs) in single-pixel imaging and illustrate its application using two experiments. Under a limited number of sampling times, we improved the resolution and recovered spectral information of interest in the ROI. Meanwhile, this scheme has high information security with high encryption and has great potential for single-pixel video and compressive multi-spectral single-pixel imaging.

The ghost imaging (GI) approach is an intriguing and promising image acquisition technique that can transmit high-quality image information in a scattering environment. In this paper, we focus on two concerns recently emerged in the GI modality: one is the vulnerability to forgery attacks in GI-based optical encryption [Opt. Lett. 45, 3917 (2020)OPLEDP0146-959210.1364/OL.392424], and the other is the potential threat of GI to personal privacy regarding non-invasive imaging [Opt. Express 28, 17232 (2020)OPEXFF1094-408710.1364/OE.391788]. The core idea is to recommend introducing weighted multiplicative signals [Opt. Express 27, 36505 (2019)OPEXFF1094-408710.1364/OE.27.036505] into the computational GI system, whether on the transmitting end or the receiving end. At the transmitting end, the random multiplicative signal can be used as an additional key that can reduce the possibility of forgery attacks, thereby increasing image transmission security. On the receiving end, the introduction of a random multiplicative signal to a spatial scattering medium makes it a “spatiotemporal” scattering medium, whose transmittance changes with time. Further, the spatiotemporal scattering medium can disable direct imaging and GI at the same time with low cost, thereby having great potential in privacy protection in daily lives.

This paper reviewed the process developments when building III-V devices onto large Si wafers using Applied Materials’ 300mm III-V metal-organic chemical vapor deposition tool (MOCVD). Anti-phase defects free GaAs films were achieved by optimizing the surface pre-cleaning and growth conditions on industrial standard 300mm Si (100) wafers. High quality growth on patterned wafers was also demonstrated for III-V FinFET applications.

Shuangchuang talents refer to talents with innovative thinking and entrepreneurial abilities. This is also the main goal of training talents for education and teaching in my country’s higher education institutions. In the process of training and teaching innovative and entrepreneurial talents, there are problems such as imperfect training facilities and insufficient teachers, which have seriously affected the training of innovative talents in universities. The rise of VR technology has provided a new way for the training of entrepreneurs and entrepreneurs, which not only greatly eases the resource input of talent education in colleges and universities, but also effectively improves the efficiency of talent training. This article conducts detailed research on the application of VR technology in talent education and training from multiple perspectives.

Ghost imaging (GI) is an imaging modality using light that has never physically interacted with the object to be imaged. The success of GI relies on the strong spatial correlation of photons. However, not all optical systems in nature are strongly spatially correlated. Two-color pseudo-thermal GI (PGI) can be viewed as such a weakly correlated system with two independent light sources. In this Letter, Deep Learning is introduced to learn the correlation between two-color speckle patterns, which solves the problem of two-color PGI with a wavelength gap of 101 nm (from 633 nm to 532 nm). Further, we retrieved dual-band ghost images using one broad-spectrum bucket detector and the reference speckle patterns at 633 nm. Our scheme provides insights into all PGI with weak correlation and also is a potential approach for multi-spectral PGI with “learned” wavelength conversion, especially for invisible wavebands.

Fourier single-pixel imaging (FSPI) technique can encode a real two-dimensional scene to one-dimensional time-varying light intensity sequences traveling in the free space. In this work, FSPI technique with weighted light source is regarded as a carrier of multi-dimensional information while capturing the object scene using a lens-free photodetector, and can carry visible and invisible optical information simultaneously utilizing a novel spectrum division multiplexing technique. A wavelength division multiplexing technique is adopted to improve the channel capacity as well, in which a total of six watermarks are embedded once. More importantly, our scheme successfully demonstrates that triple information (host scene, visible, and invisible optical information) can be transmitted and retrieved with high fidelity in four noisy environments including external attack, environmental interference light, thick and dynamic scattering.