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This paper proposes a support structure topology optimization method for laser powder bed fusion-processed metal parts, which could effectively avoid part failures caused by over-distortions. Multiple additive manufacturing issues are considered and overcome with the proposed method, including the self-support issue, minimum length scale control, and support structure easy removal. Specifically, a finite element analysis model based on the inherent strain method is proposed to simulate the complex mechanical behavior in the additive manufacturing process. Then, according to the layer-by-layer inherent strain-based fast simulation model, the gravity compliance and residual distortion minimization topology optimization problem incorporating the self-support constraint, mass fraction constraint, minimum length-scale control, and support easy-removal constraint is formulated. Accordingly the critical sensitivity information is derived through the adjoint analysis. Finally, the proposed method is applied to several 2D and 3D benchmark examples to demonstrate the effectiveness on residual distortion control. The influences of different optimization strategies, weighting parameters, and minimum length-scale limits are comparatively explored. A comprehensive discussion is presented at the end to summarize the numerical phenomena. [ABSTRACT FROM AUTHOR]

To improve the uniformity of asphalt mixtures, optimizing the particle distribution is essential, and the screw conveyor of paver plays a critical role in this process. In this regard, a parameter optimization strategy based on the discrete element method and response surface methodology (RSM) is proposed. First, a discrete element model is developed for spiral material separation and asphalt mixture particles. Next, uniformity evaluation indicators are used to analyze the impact of individual parameters on particle uniformity. Then, simulation experiments are conducted under varying material level coefficients and rotational speeds, and a regression model is developed to analyze the impact of coupling factors using RSM. Afterward, different algorithms are employed to optimize the parameters of the model, and the results show that the particle swarm optimization algorithm is better than the traditional hill climbing algorithm. Last, field tests are conducted to verify the feasibility of the proposed optimization strategy. The optimal theoretical parameter of the material level coefficient is 0.95, and the rotational speed is 53 rpm. Overall, the proposed strategy offers an effective and accurate model for simulating the process of particle separation, which can lead to improved uniformity of asphalt mixtures. [ABSTRACT FROM AUTHOR]

Rotational inertial navigation system (RINS) could improve the navigation performance by rotating the IMU around gimbals, and the structure and function of the dual-axis RINS also help realize the process of self-calibration. However, the gyro–accelerometer asynchronous time is not considered in current studies. Coupled into the navigation error, the gyro–accelerometer asynchronous time can lead to velocity accuracy decline during the process of rotation. Therefore, the modeling and calibration of the gyro–accelerometer asynchronous time would enhance the systemic reliability. In this article, in order to solve the abovementioned problem: 1) we model the gyro–accelerometer asynchronous time and perform an error analysis of gyro–accelerometer asynchronous time; 2) we propose a compensation method of the outer lever arm to improve the accuracy of the observed velocity and position; and 3) we derive a continuous linear 40-D RINS error model considering the abovementioned two error parameters compared with the traditional method, the PWCS method, and the SVD method is utilized to provide the observability degrees of the proposed state during the self-calibration process. Experimental results illustrated that the proposed method can improve the accuracy in the long-endurance navigation. [ABSTRACT FROM AUTHOR]

A significant issue of land vehicle navigation is in-motion attitude alignment of the odometer (OD)-aided strapdown inertial navigation system (SINS). The consecutive OD outliers can occur due to sudden wheel slipping and skidding while vehicle maneuvering. They seriously reduce the robustness and precision of attitude alignment. In this paper, we investigate a robust in-motion attitude alignment method for the OD-aided SINS. The method consists of in-motion coarse alignment and in-motion fine alignment. In the in-motion coarse alignment process, we developed Huber's M-estimation and integral formula based robust Kalman filter (HRKF/IF-CA), which can restrain the interference of consecutive OD outliers on reconstructed observation vectors. Thus, HRKF/IF-CA can contribute to better coarse attitude results. The next process is in-motion fine alignment. Under the popular repeated backtracking scheme, we investigate HRKF based fine alignment (HRKF-FA) with the SINS/OD summed measurement model. HRKF-FA can refine attitude alignment and restrain the interference of consecutive OD outliers simultaneously. Finally, the proposed method is evaluated by simulation and vehicle test. The attitude alignment results show that this method can achieve reasonable attitude results, and the interference of consecutive OD outliers caused by sudden wheel slipping and skidding can be greatly restrained. [ABSTRACT FROM AUTHOR]

In order to understand rice blast resistance gene patterns in rice landraces from Myanmar and Laos, we analysed the Pita, Pib, Pikh, Pi9 and Pi5 genes in 80 landraces through the use of functional molecular markers and functional fragment sequencing. These landraces were separated into four haplotypes (H1–H4) based upon three mutations identified in the Pita sequence. All four haplotypes were detected among landraces from Myanmar, whereas only the H1 and H2 haplotypes were detected among landraces from Laos. We additionally grouped landraces carrying 0–4 resistance genes into 18 genotypes based upon their resistance-susceptibility patterns and found that 16 of these genotypes were detected among Myanmar landraces at relative frequencies ranging from 2.50–12.50%, while 10 were detected among landraces from Laos at relative frequencies of 2.50–42.50%. The 'Pib(+) pikh(−) pi9(−) pi5(−) pita(−)' genotype was found to be dominant, accounting for 12.5 and 42.5% of landraces from Myanmar and Laos, respectively. The Pib, Pikh, Pi5 and Pita genes were detected in 52.50, 32.50, 37.50 and 30.00% of landraces from Myanmar respectively, whereas they were detected in 52.50, 12.50, 30.00 and 17.50% of landraces from Laos, respectively. The Pi9 gene was rarely detected among analysed landraces and was particularly rare in those from Laos. These findings suggest that rice landraces from Myanmar are more genetically diverse than those from Laos, with clear differences in blast resistance gene patterns between landraces from these two countries. [ABSTRACT FROM AUTHOR]

Most image encryption algorithms encrypt the whole image, but only part of the data is important in the image. In this paper, we propose a multidimensional chaotic image encryption algorithm based on the region of interest (ROI). The histogram of oriented gradients (HOG) feature extraction and support vector machine (SVM) are used to separate the region of interest from the whole image. Then, the region of interest pixels is messed up by using the improved Henon sequence, Joseph sequence and the region of interest pixels are diffused by using the unified chaotic sequence to hide the sensitive information in the image, so as to achieve the purpose of private protection. Furthermore, the improved logistic sequence is used to hide the edge information of the target image to achieve the tradeoff between the secrecy of information and the complexity of encryption. A series of analyses are carried out including key space analysis, key sensitivity analysis, statistical analysis, information entropy analysis, analysis of the fixed-point obscuration analysis, quality analysis and image decryption for our encryption algorithm. Through experiments and comparisons, the proposed algorithm has good performance in encrypting image and coping with various invasions. The image encryption algorithm based on ROI has a good performance of security, moreover through the main encryption of ROI can effectively shorten the encryption time, so as to achieve the compromise of security and computational complexity. [ABSTRACT FROM AUTHOR]

Recently, with the improvement of attack technology and computational capability, how to meet the security application of streaming media data has become a significant issue, especially for systems with a high standard of security. This paper presents a real-time authentication scheme for P2P streaming media transmission system, which can at least meet the application of identity authentication, tamper location, and error retransmission. We first tailor and employ off-the-shelf algorithms to propose two types of watermarking algorithms (the Feature Watermarker and the Identity Watermarker). Then, the sliding window is employed to group and provision the above two types of watermarks in the overall authentication scheme. Several metrics are employed to indicate our watermarking meets the application of invisibility and has a very low false alarm rate and missing alarm rate after computing and choosing viable thresholds. Moreover, we sketch an "Attack List" aiming at detecting and deal with malicious behaviors effectively, including two types of attacks which is irresistible for the common watermarking algorithms (Re-embedded attack and Destruction of watermark). The delay in transmission turns out to be acceptable by reasonably tailoring crucial parameters. [ABSTRACT FROM AUTHOR]

Key message: AtWRKY53 is an early factor in drought response and activated expression of AtWRKY53 regulates stomatal movement via reduction of H O content and promotion of starch metabolism in guard cells. Abstract: Drought is one of the most serious environmental factors limiting the productivity of agricultural crops worldwide. However, the mechanisms underlying drought tolerance in plants remain unclear. AtWRKY53 belongs to the group III of WRKY transcription factors. In this study, we observed both the mRNA and protein products of this gene are rapidly induced under drought conditions. Phenotypic analysis showed AtWRKY53 overexpression lines were hypersensitive to drought stress compared with Col-0 plants. The results of stomatal movement assays and abscisic acid (ABA) content detection indicated that the impaired stomatal closure of 53OV lines was independent of ABA. Further analysis found that WRKY53 regulated stomatal movement via reducing the HO content and promoting the starch metabolism in guard cells. The results of quantitative real-time reverse transcriptase PCR showed that the expression levels of CAT2, CAT3 and QQS were up-regulated in 53OV lines. Chromatin immunoprecipitation assays demonstrated that AtWRKY53 can directly bind to the QQS promoter sequences, thus led to increased starch metabolism. In summary, our results indicated that the activated expression of AtWRKY53 inhibited stomatal closure by reducing HO content and facilitated stomatal opening by promoting starch degradation. [ABSTRACT FROM AUTHOR]

Resistance ( R) gene Pit in rice, encodes a protein with nucleotide binding sites-leucine rich repeat domain, prevents infections by strains of Magnaporthe oryzae in a gene for gene manner. Here, we analyzed the open reading frame (ORF) of Pit in 26 varieties including Oryza sativa L. subsp . indica Kato (Aus), indica (IND), temperate japonica (TEJ), tropical japonica (TRJ), aromatic (ARO) subgroups of Oryza sativa, and nine accessions of wild rice relatives including O. nivara and O. rufipogon from different growing areas. Twenty-one nucleotide differences were found within the ORFs of 35 accessions. Translation of these ORFs revealed a total of 11 Pit variants, seven of which were novel. Furthermore, variant H1 was identified in O. sativa and O. nivara; H2 and H10 were identified in O. sativa and O. rufipogon. H3, H4, and H11 were only found in O. sativa. H11 was the common type of TEJ and ARO; H3 and H4 was the specific type of TRJ and IND, respectively. H5, H6, and H7 were specific haplotypes of O. nivara, while, H8 and H9 were specific haplotypes of O. rufipogon. These results suggest that Pit is an ancient gene that exists before formation of rice domestication subgroups. [ABSTRACT FROM AUTHOR]