UAV-supported intelligent truth discovery to achieve low-cost communications in mobile crowd sensing

Unmanned and aerial systems as interactors among different system components for communications,have opened up great opportunities for truth data discovery in Mobile Crowd Sensing(MCS)which has not been properly solved in the literature.In this paper,an Unmanned Aerial Vehicles-supported Intelligent Truth Discovery(UAV-ITD)scheme is proposed to obtain truth data at low-cost communications for MCS.The main innovations of the UAV-ITD scheme are as follows:(1)UAV-ITD scheme takes the first step in employing UAV joint Deep Matrix Factorization(DMF)to discover truth data based on the trust mechanism for an Information Elicitation Without Verification(IEWV)problem in MCS.(2)This paper introduces a truth data discovery scheme for the first time that only needs to collect a part of n data samples to infer the data of the entire network with high accuracy,which saves more communication costs than most previous data collection schemes,where they collect n or kn data samples.Finally,we conducted extensive experiments to evaluate the UAV-ITD scheme.The results show that compared with previous schemes,our scheme can reduce estimated truth error by 52.25%–96.09%,increase the accuracy of workers’trust evaluation by 0.68–61.82 times,and save recruitment costs by 24.08%–54.15%in truth data discovery.

MD Simulation of Diffusion Behaviors in Collision Welding Processes of Al-Cu, Al-Al, Cu-Cu

To investigate the effects of material combinations and velocity conditions on atomic diffusion behavior near collision interfaces,this study simulates the atomic diffusion behavior near collision interfaces in Cu-Al,Al-Al and Cu-Cu combinations fabricated through collision welding using molecular dynamic(MD)simulation.The atomic diffusion behaviors are compared between similar metal combinations(Al-Al,Cu-Cu)and dissimilar metal combinations(Al-Cu).By combining the simulation results and classical diffusion theory,the diffusion coefficients for similar and dissimilar metal material combinations under different velocity conditions are obtained.The effects of material combinations and collision velocity on diffusion behaviors are also discussed.The diffusion behaviors of dissimilar material combinations strongly depend on the transverse velocity,whereas those of the similar material combinations are more dependent on the longitudinal velocity.These findings can provide guidance for optimizing welding parameters.

Study of brain morphology change in Alzheimer’s disease and amnestic mild cognitive impairment compared with normal controls

Background With an aggravated social ageing level, the number of patients with Alzheimer's disease (AD) is gradually increasing, and mild cognitive impairment (MCI) is considered to be an early form of Alzheimer's disease. How to distinguish diseases in the early stage for the purposes of early diagnosis and treatment is an important topic. Aims The purpose of our study was to investigate the differences in brain cortical thickness and surface area among elderly patients with AD, elderly patients with amnestic MCI (aMCI) and normal controls (NC). Methods 20 AD patients, 21 aMCIs and 25 NC were recruited in the study. FreeSurfer software was used to calculate cortical thickness and surface area among groups. Results The patients with AD had less cortical thickness both in the left and right hemisphere in 17 of the 36 brain regions examined than the patients with aMCI or NC. The patients with AD also had smaller cerebral surface area both in the left and right hemisphere in 3 of the 36 brain regions examined than the patients with aMCI or NC. Compared with the NC, the patients with aMCI only had slight atrophy in the inferior parietal lobe of the left hemisphere, and no significant difference was found. Conclusion AD, as well as aMCI (to a lesser extent), is associated with reduced cortical thickness and surface area in a few brain regions associated with cognitive impairment. These results suggest that cortical thickness and surface area could be used for early detection of AD.

A Cross Language Code Security Audit Framework Based on Normalized Representation

With the rapid development of information technology,audit objects and audit itself are more and more inseparable from software.As an important means of software security audit,code security audit will become an important aspect of future audit that cannot be ignored.However,the existing code security audit ismainly based on source code,which is difficult to meet the audit needs of more and more programming languages and binary commercial software.Based on the idea of normalized transformation,this paper constructs a cross language code security audit framework(CLCSA).CLCSA first uses compile/decompile technology to convert different highlevel programming languages and binary codes into normalized representation,and then usesmachine learning technology to build a cross language code security audit model based on normalized representation to evaluate code security and find out possible code security vulnerabilities.Finally,for the discovered vulnerabilities,the heuristic search strategy will be used to find the best repair scheme from the existing normalized representation sample library for automatic repair,which can improve the effectiveness of code security audit.CLCSA realizes the normalized code security audit of different types and levels of code,which provides a strong support for improving the breadth and depth of code security audit.

Vanadium-modified hard carbon spheres with sufficient pseudographitic domains as high-performance anode for sodium-ion batteries

Hard carbons are promising anode materials for sodium-ion batteries.To meet practical requirements,searching for durable and conductive carbon with a stable interface is of great importance.Here,we prepare a series of vanadiummodified hard carbon submicrospheres by using hydrothermal carbonization followed by high-temperature pyrolysis.Significantly,the introduction of vanadium can facilitate the nucleation and uniform growth of carbon spheres and generate abundant V-O-C interface bonds,thus optimizing the reaction kinetic.Meanwhile,the optimized hard carbon spheres modified by vanadium carbide,with sufficient pseudographitic domains,provide more active sites for Na ion migration and storage.As a result,the HC/VC-1300 electrode exhibits excellent Na storage performance,including a high capacity of 420 mAh g^(-1) at 50mA g^(-1) and good rate capability at 1 A g^(-1).This study proposes a new strategy for the synthesis of hard carbon spheres with high tap density and emphasizes the key role of pseudographitic structure for Na storage and interface stabilization.

All-optical object identification and threedimensional reconstruction based on optical computing metasurface

Object identification and three-dimensional reconstruction techniques are always attractive research interests in machine vision,virtual reality,augmented reality,and biomedical engineering.Optical computing metasurface,as a two-dimensional artificial design component,has displayed the supernormal character of controlling phase,amplitude,polarization,and frequency distributions of the light beam,capable of performing mathematical operations on the input light field.Here,we propose and demonstrate an all-optical object identification technique based on optical computing metasurface,and apply it to 3D reconstruction.Unlike traditional mechanisms,this scheme reduces memory consumption in the processing of the contour surface extraction.The identification and reconstruction of experimental results from high-contrast and low-contrast objects agree well with the real objects.The exploration of the all-optical object identification and 3D reconstruction techniques provides potential applications of high efficiencies,low consumption,and compact systems.

Multiple Vandermonde Decomposition Based Channel Estimation for Mm Wave MIMO High-Mobility Communication in 5G and Beyond

Millimeter wave(mmWave)massive massive multiple input multiple output(MIMO)technique has been regarded as the viable solution for vehicular communications in 5G and beyond.To achieve the substantial increase in date rates,it is important to take an effective channel state information(CSI).However,existing channel estimation strategies are unavailable since the users high-mobility.To solve above issues,in this paper,inspired by a specific antenna structure,we propose a novel approach for fast time-varying channel estimation.Specifically,by considering the vehicle scenario with high-mobility,a corresponding mathematical model is firstly established.Then,based on the special structural of the sparse array,the switch network is used to replace the convention phase shifter of mmWave hybrid system,which can effectively reduce the number of radio-frequency(RF)chains and antennas.Furthermore,by solving the semidefinite programming(SDP)duality problem,the Doppler frequency and path parameters are effectively estimated.Simulation results are shown that the computational complexity and estimation accuracy of the proposed algorithm is superior than that of the traditional schemes.

The Relationship between Rural Left-Behind Children’s Physical Activity and Hope:The Mediating Effects of Perceived Social Support

It has been confirmed in previous studies that there is a positive correlation between physical activity and hope.In this study,rural left-behind children in China was taken as the participants to investigate the impact of physical activity on hope in rural left-behind children and examine the mediating role of perceived social support in the relationship between physical activity and hope.797 valid copies of the questionnaire were collected from China.Pearson correlation coefficient was employed to analyze the relationship between physical activity and hope;SEM and Bootstrap were used to test the mediating effect of perceived social support.The results show that physical activity can not only directly and positively predict the level of hope in rural leftbehind children but can also predict the level of hope through perceived social support;perceived social support plays a mediating role in the relationship between physical activity and hope.These results highlight the necessity to pay more attention to the physical activity of left-behind children and the possibility to improve the level of hope by increasing their physical activity;at the same time,the acquisition of more material,emotional and psychological support from teachers and guardians is more conducive to improving the sense of hope in left-behind children.These findings can deepen the understanding of the sense of hope in left-behind children,and provide new methods for and enlightenments on improving the level of hope in left-behind children.

Adaptive Reversible Visible Watermarking Based on Total Variation for BTC-Compressed Images

Few previous Reversible Visible Watermarking(RVW)schemes have both good transparency and watermark visibility.An adaptive RVW scheme that integrates Total Variation and visual perception in Block Truncation Coding(BTC)compressed domain,called TVB-RVW is proposed in this paper.A new mean image estimation method for BTC-compressed images is first developed with the help of Total Variation.Then,a visual perception factor computation model is devised by fusing texture and luminance characteristics.An adaptive watermark embedding strategy is used to embed the visible watermark with the effect of the visual perception factor in the BTC domain.Moreover,a lossless embedding method of the encrypted visible watermark is exploited to deter illegal watermark removal.The visible watermark can be removed since the visual perception factor and the estimated mean image remain unchanged before and after watermark embedding.Extensive experiments validate the superiority of the proposed algorithm over previous RVW schemes in BTC in terms of the visual quality of watermarked images and watermark visibility,and it can achieve a good balance between transparency and watermark visibility.

An Intelligent Secure Adversarial Examples Detection Scheme in Heterogeneous Complex Environments

Image-denoising techniques are widely used to defend against Adversarial Examples(AEs).However,denoising alone cannot completely eliminate adversarial perturbations.The remaining perturbations tend to amplify as they propagate through deeper layers of the network,leading to misclassifications.Moreover,image denoising compromises the classification accuracy of original examples.To address these challenges in AE defense through image denoising,this paper proposes a novel AE detection technique.The proposed technique combines multiple traditional image-denoising algorithms and Convolutional Neural Network(CNN)network structures.The used detector model integrates the classification results of different models as the input to the detector and calculates the final output of the detector based on a machine-learning voting algorithm.By analyzing the discrepancy between predictions made by the model on original examples and denoised examples,AEs are detected effectively.This technique reduces computational overhead without modifying the model structure or parameters,effectively avoiding the error amplification caused by denoising.The proposed approach demonstrates excellent detection performance against mainstream AE attacks.Experimental results show outstanding detection performance in well-known AE attacks,including Fast Gradient Sign Method(FGSM),Basic Iteration Method(BIM),DeepFool,and Carlini&Wagner(C&W),achieving a 94%success rate in FGSM detection,while only reducing the accuracy of clean examples by 4%.

A Novel Secure Scan Design Based on Delayed Physical Unclonable Function

The advanced integrated circuits have been widely used in various situations including the Internet of Things,wireless communication,etc.But its manufacturing process exists unreliability,so cryptographic chips must be rigorously tested.Due to scan testing provides high test coverage,it is applied to the testing of cryptographic integrated circuits.However,while providing good controllability and observability,it also provides attackers with a backdoor to steal keys.In the text,a novel protection scheme is put forward to resist scan-based attacks,in which we first use the responses generated by a strong physical unclonable function circuit to solidify fuseantifuse structures in a non-linear shift register(NLSR),then determine the scan input code according to the configuration of the fuse-antifuse structures and the styles of connection between the NLSR cells and the scan cells.If the key is right,the chip can be tested normally;otherwise,the data in the scan chain cannot be propagated normally,it is also impossible for illegal users to derive the desired scan data.The proposed technique not only enhances the security of cryptographic chips,but also incurs acceptable overhead.

Read-Write Dependency Aware Register Allocation

Read-write dependency is an important factor restricting software efficiency.Timing Speculative(TS)is a processing architecture aiming to improve energy efficiency of microprocessors.Timing error rate,influenced by the read-write dependency,bottlenecks the voltage down-scaling and so the energy efficiency of TS processors.We proposed a method called Read-Write Dependency Aware Register Allocation.It is based on the Read-Write Dependency aware Interference Graph(RWDIG)conception.Registers are reallocated to loosen the read-write dependencies,so resulting in a reduction of timing errors.The traditional no operation(Nop)padding method is also redesigned to increase the distance value to above 2.We analyzed the dependencies of registers and maximized the average distance value of read and write dependencies.Experimental results showed that we can reduce all read-write dependency by Nop padding,as well as the overhead timing errors.An energy saving of approximately 7%was achieved.

The Review of Secret Image Sharing

Secret image sharing(SIS)is a significant research topic of image information hiding,which divides the image into multiple shares and dis-tributes them to multiple parties for management and preservation.In order to reconstruct the original image,a subset with predetermined number of shares is needed.And just because it is not necessary to use all of the shares to make a reconstruction,SIS creates a high fault tolerance which breaks the limitations of traditional image protection methods,but at the same time,it causes a reduce of safety.Recently,new technologies,such as deep learning and blockchain,have been applied into SIS to improve its efficiency and security.This paper gives an overall review of SIS,discusses four important approaches for SIS,and makes a comparison analysis among them from the perspectives of pixel expansion,tamper resistance,etc.At the end,this paper indicates the possible research directions of SIS in the future.

Geospatial-Based Analysis of Balance in Elementary Education—Taking Elementary Schools in Changsha Five Core Districts as Examples

The balanced development of the elementary education sector has been a long goal pursued by the education departments of various places, and is also an outcome expected by the people. Based on a study of the equilibrium of the spatial distribution of the capacity saturation models of all the primary schools in Changsha’s (China) five core districts, the results show that the overall geographical distribution of the primary schools in Changsha is relatively balanced, based on the natural characteristics of Changsha, such as human geography, and the moderate gradient between the central urban area and the primary schools in the suburbs and outer suburbs. Then the Theil index model was introduced, and the results of the model analysis show that the differences between elementary schools in Changsha urban area are relatively small, and the main differences originate from between districts rather than within districts, and subtle differences among regions mainly reflect in the teacher strength.

Mathematical modelling and numerical optimization of particle heating process in copper flash furnace

A mathematical model of the particle heating process in the reaction shaft of flash smelting furnace was established and the calculation was performed.The results indicate that radiation plays a significant role in the heat transfer process within the first 0.6 m in the upper part of the reaction shaft,whilst the convection is dominant in the area below 0.6 m for the particle heating.In order to accelerate the particle ignition,it is necessary to enhance the convection,thus to speed up the particle heating.A high-speed preheated oxygen jet technology was then suggested to replace the nature gas combustion in the flash furnace,aiming to create a lateral disturbance in the gaseous phase around the particles,so as to achieve a slip velocity between the two phases and a high convective heat transfer coefficient.Numerical simulation was carried out for the cases with the high-speed oxygen jet and the normal nature gas burners.The results show that with the high-speed jet technology,particles are heated up more rapidly and ignited much earlier,especially within the area of the radial range of R=0.3−0.6 m.As a result,a more efficient smelting process can be achieved under the same operational condition.

Study on element detection and its correction in iron ore concentrate based on a prompt gamma-neutron activation analysis system

A prompt gamma-neutron activation analysis(PGNAA) system was developed to detect the iron content of iron ore concentrate. Because of the self-absorption effect of gamma-rays and neutrons, and the interference of chlorine in the neutron field, the linear relationship between the iron analytical coefficient and total iron content was poor, increasing the error in the quantitative analysis. To solve this problem, gamma-ray self-absorption compensation and a neutron field correction algorithm were proposed, and the experimental results have been corrected using this algorithm. The results show that the linear relationship between the iron analytical coefficient and total iron content was considerably improved after the correction. The linear correlation coefficients reached 0.99 or more.

Green Synthesis of Nitrogen-to-Ammonia Fixation: Past, Present, and Future

The nitrogen(N2)-to-ammonia(NH3)fixation driven by renewable energy has an attractive prospect to relieve the global warming and reduce the consumption of fossil fuels.Ideally,photocatalytic,electrochemical,and photoelectrochemical approaches are developed as the next-generation NH3 synthesis technologies to substitute the Haber–Bosch method.However,the NH3 yield rate of nitrogen reduction reaction(NRR)by green approaches is extremely low,resulting in the current dilemma of NRR and contamination issues.Thus,in this mini review,the past advances on the sustainable NRR are briefly summarized in the three aspects as follows:the selectivity and adjustment of various catalysts,the type of electrolyte/solvent system,and the investigation of reaction conditions.Subsequently,the recent critical activities in the area of sustainable NH3 synthesis are analyzed and discussed deeply,and a perspective for rational and healthy development of this area is provided positively。

ASYMPTOTIC PROPERTIES OF A BRANCHING RANDOM WALK WITH A RANDOM ENVIRONMENT IN TIME

We consider a branching random walk in an independent and identically distributed random environment ξ=(ξn) indexed by the time. Let W be the limit of the martingale Wn=∫e^-txZn(dx)/Eξ∫e^-txZn(dx), with Zn denoting the counting measure of particles of generation n, and Eξ the conditional expectation given the environment ξ. We find necessary and sufficient conditions for the existence of quenched moments and weighted moments of W, when W is non-degenerate.

Recycling of waste carbon residue from spent lithium-ion batteries via constant-pressure acid leaching

Waste carbon residue(WCR)was efficiently detoxicated and regenerated to high-purity graphite(PGC)used in lithium-ion batteries through the constant-pressure acid leaching technique.The leaching conditions were optimized by the combination of orthogonal and single-factor experiments.Results show that PGC with 99.5%purity is regenerated at temperature of 60℃,initial acid concentration of 12%,leaching time of 180 min,and liquid-to-solid ratio of 25:1,satisfying the requirements of commercial graphite.Meanwhile,the sodium hydroxide precipitation process was designed to recover valuable components from leachate efficiently.Ni,Co,Mn,and Al recoveries reach 96.92%,87.5%,97.83%,and 92.17%,respectively,at pH=11.Moreover,the co-product NaF can be recovered with purity over 99%via evaporative crystallization.The loss rate of fluorine is less than 0.5%,thereby eliminating the pollution risk of fluorine to the environment.The proposed process shows considerable environmental and economic benefits.

Wet Desulfurization of High-Sulfur Petroleum Coke Improved via Pre-calcination,H_(2)O_(2) Treatment,and Ultrasound

This work reports an improved method for the wet desulfurization of high-sulfur petroleum coke(petcoke)powder based on the combination of pre-calcination,H_(2)O_(2),and ultrasound.The results demonstrated that over 45%of the sulfur atoms were efficiently removed from Tianjin coke and Qilu coke(particle size<0.1 mm)by pre-calcination at 800℃ for 6 h followed by desulfurization with HNO3(8 mol/L)and H_(2)O_(2)(2 mol/L)solution at a reaction temperature of 60℃,a reaction time of 6 h,a liquid-to-solid ratio of 10 mL/g,and a 40 kHz ultrasonic power of 400 W.In addition,the specific surface area of the petcoke particles increased from 0.7 to 301.49 m^(2)/g.After desulfurization,the pore size distribution of the petcoke particles was more concentrated on micropores compared with the samples prior to petcoke treatment.Reactive force field molecular dynamics simulation results indicated that HNO_(3) continuously oxidized the carbon atoms adjacent to sulfur atoms in the petcoke macromolecules and promoted sulfur removal from petcoke via the cleavage of C-S bonds.The sulfur transformation mechanism can be summarized as follows:thiophene sulfur→branched chain carbon sulfur→CO_(2)S→C_(2)O_(2)S→C_(2)O_(3)NS→C_(2)O_(4)S→CO_(2)S.