Enhanced Path Planning and Obstacle Avoidance Based on High-Precision Mapping and Positioning.

High-precision positioning and multi-target detection have been proposed as key technologies for robotic path planning and obstacle avoidance. First, the Cartographer algorithm was used to generate high-quality maps. Then, the iterative nearest point (ICP) and the occupation probability algorithms were combined to scan and match the local point cloud, and the positions and attitudes of the robot were obtained. Furthermore, Sparse Matrix Pose Optimization was carried out to improve the positioning accuracy. The positioning accuracy of the robot in x and y directions was kept within 5 cm, the angle error was controlled within 2°, and the positioning time was reduced by 40%. An improved timing elastic band (TEB) algorithm was proposed to guide the robot to move safely and smoothly. A critical factor was introduced to adjust the distance between the waypoints and the obstacle, generating a safer trajectory, and increasing the constraint of acceleration and end speed; thus, smooth navigation of the robot to the target point was achieved. The experimental results showed that, in the case of multiple obstacles being present, the robot could choose the path with fewer obstacles, and the robot moved smoothly when facing turns and approaching the target point by reducing its overshoot. The proposed mapping, positioning, and improved TEB algorithms were effective for high-precision positioning and efficient multi-target detection.

Visual Sensing and Depth Perception for Welding Robots and Their Industrial Applications.

With the rapid development of vision sensing, artificial intelligence, and robotics technology, one of the challenges we face is installing more advanced vision sensors on welding robots to achieve intelligent welding manufacturing and obtain high-quality welding components. Depth perception is one of the bottlenecks in the development of welding sensors. This review provides an assessment of active and passive sensing methods for depth perception and classifies and elaborates on the depth perception mechanisms based on monocular vision, binocular vision, and multi-view vision. It explores the principles and means of using deep learning for depth perception in robotic welding processes. Further, the application of welding robot visual perception in different industrial scenarios is summarized. Finally, the problems and countermeasures of welding robot visual perception technology are analyzed, and developments for the future are proposed. This review has analyzed a total of 2662 articles and cited 152 as references. The potential future research topics are suggested to include deep learning for object detection and recognition, transfer deep learning for welding robot adaptation, developing multi-modal sensor fusion, integrating models and hardware, and performing a comprehensive requirement analysis and system evaluation in collaboration with welding experts to design a multi-modal sensor fusion architecture.

DAssd-Net: A Lightweight Steel Surface Defect Detection Model Based on Multi-Branch Dilated Convolution Aggregation and Multi-Domain Perception Detection Head.

During steel production, various defects often appear on the surface of the steel, such as cracks, pores, scars, and inclusions. These defects may seriously decrease steel quality or performance, so how to timely and accurately detect defects has great technical significance. This paper proposes a lightweight model based on multi-branch dilated convolution aggregation and multi-domain perception detection head, DAssd-Net, for steel surface defect detection. First, a multi-branch Dilated Convolution Aggregation Module (DCAM) is proposed as a feature learning structure for the feature augmentation networks. Second, to better capture spatial (location) information and to suppress channel redundancy, we propose a Dilated Convolution and Channel Attention Fusion Module (DCM) and Dilated Convolution and Spatial Attention Fusion Module (DSM) as feature enhancement modules for the regression and classification tasks in the detection head. Third, through experiments and heat map visualization analysis, we have used DAssd-Net to improve the receptive field of the model while paying attention to the target spatial location and redundant channel feature suppression. DAssd-Net is shown to achieve 81.97% mAP accuracy on the NEU-DET dataset, while the model size is only 18.7 MB. Compared with the latest YOLOv8 model, the mAP increased by 4.69%, and the model size was reduced by 23.9 MB, which has the advantage of being lightweight.

ZNF804A rs1344706 is associated with cortical thickness, surface area, and cortical volume of the unmedicated first episode schizophrenia and healthy controls.

The effects of ZNF804A rs1344706, a prominent susceptibility gene for schizophrenia, on gray matter (GM) structure in unmedicated schizophrenia (SZ) patients are still unknown, although several previous studies investigated the effects in medicated SZ patients and healthy controls (HC). Analyzing cortical thickness, surface area, and GM volume simultaneously may provide a more precise and complete picture of the effects. We genotyped 59 unmedicated first episode SZ patients and 60 healthy controls for the ZNF804A single nucleotide polymorphism (SNP) rs1344706, and examined between-group differences in cortical thickness, surface area, and cortical volume using a full-factorial 2 × 2 analysis of variance (ANOVA). We found the risk allele (T) in ZNF804A rs1344706, compared to the non-risk allele (G), was associated with thinner cortex in the bilateral precuneus, left precentral gyrus, and several other regions, associated with a smaller cortical surface area in the left superior parietal, precuneus cortex and left superior frontal, and associated with a lower cortical volume in the left superior frontal, left precentral, and right precuneus in SZ patients. In contrast, in the controls, the T allele was associated with the increased cortical measurements compared to the G allele in the same regions as those mentioned above. ZNF804A rs1344706 has significant, but different, effects on cortical thickness, surface area, and cortical volume in multiple regions of the brain cortex. Our findings suggest that ZNF804A rs1344706 may aggravate the risk for schizophrenia by exerting its effects on cortical thickness, surface area, and cortical volume in these brain regions.

Crack-Tip Opening Displacement of Girth Welds in a Lean X70 Pipeline Steel.

Crack-tip opening displacement (CTOD) tests were conducted on girth welds of two API 5L X70 pipeline steels (pipe A and pipe B) to investigate the influence of base metal composition on the fracture toughness of the joint. CTOD measurements across the weld showed that the weld fusion zone had the lowest CTOD values for both pipes, with pipe B having a higher CTOD value than pipe A. Detailed microstructure characterization of the multi-pass weld showed that the fusion zone in both pipes consisted of three distinct zones: the columnar zone, the coarse equiaxed zone, and the fine equiaxed zone. Both the columnar zone and coarse-grained equiaxed zone had acicular ferrite and grain boundary ferrite microstructures, whereas the fine-grained equiaxed zone had a finer ferrite microstructure compared to the other two zones. The main difference between the two pipes was the variation in ferrite grain sizes and the volume fractions of grain boundary ferrite and acicular ferrite. In comparison to pipe B, pipe A, with a higher concentration of Mo, Ni, and Cu in both the base metal and the weld fusion zones, consisted of a higher volume fraction of grain boundary ferrite and a lower volume fraction of acicular ferrite in the columnar and coarse-grained equiaxed zones. The lower concentration of Mo, Ni, and Cu in pipe B likely resulted in the formation of a predominantly acicular ferrite microstructure in the fusion zone, thereby improving the toughness of the weld joint in comparison to pipe A.

Effect of Fusion Boundary Microstructure on Flow-Accelerated Corrosion Cracking.

Flow-accelerated corrosion (FAC) preferentially attacks the downstream heat-affected zone of the root-pass weld in steam pipe systems. A detailed characterization identifies the fusion boundary as the initiation location for the attack. Alloying elements are found depleted along the weld fusion boundary, and multiple welding thermal cycles and repetitive austenite-to-ferrite phase transformations result in an increased proportion of grains with Goss {110}<001> texture along the fusion boundary. The synergistic effects of chemical segregation and the Schmid factor may contribute to the preferential initiation of FAC cracks along the root weld fusion boundary, making it the weakest link for FAC attack in steam pipe girth welds.

[A study of cerebral cortex in untreated first-episode schizophrenics].

OBJECTIVE: To detect the changes of cortical thickness and cortical surface area in untreated patients of first-episode schizophrenia. METHODS: Fifty-seven untreated patients of first-episode schizophrenia (SCZ) hospitalized from September 2009 to March 2012 at Department of Psychiatry, Third Affiliated Hospital, SUN Yat-sen University and 57 healthy controls (HC) recruited by advertising during the same period underwent a high resolution three-dimensional magnetic resonance imaging of brain structures. And cortical-surface based technique was used to analyze the cortical thickness and cortical surface area. The general linear model (GLM) was employed to detect the differences of cortical thickness and cortical surface area between two groups. RESULTS: were corrected for multiple comparisons by the Monte Carlo simulation method. RESULTS: As compared with HC, the cortical thickness of left superior frontal, left caudal middle cingulate, left lateral occipital, right superior frontal, right superior temporal and right fusiform regions in SCZ decreased by 6.0%, 7.2%, 8.2%, 5.2%, 7.1% and 6.0% respectively. And the largest reductions occurred in left lateral occipital regions. Cortical surface area of each brain regions in SCZ had no significant difference with HC. CONCLUSION: Cortical thickness reductions exist in multiple brain regions in schizophrenia. It may be the neuropathological mechanisms of schizophrenia.

[Diffusion tensor imaging analyses of white matter in healthy siblings of schizophrenics].

OBJECTIVE: To explore the diffusion tensor imaging (DTI) features of white matter in healthy siblings of schizophrenics. METHODS: Twenty healthy siblings of schizophrenics and 45 healthy controls without a family history of mental disorder. They responded to advertised recruitment during December 2009 and March 2012. All participants underwent diffusion weighted magnetic resonance images with a single-shot echo planar imaging (EPI) sequence aligned to straight axial plane. The fractional anisotropy (FA) images of two groups underwent two-sample t-test with SPM5 software. RESULTS: The healthy siblings of schizophrenics demonstrated a significant decrease of regional white matter FA values in right anterior cingulated (MNI: x = 9, y = 43, z = 4; cluster = 106). CONCLUSION: Reduced white matter integrity in right anterior cingulated may be a risk actor of schizophrenia.

[Diffusion tensor imaging analyses of white matter at an early stage of first-episode schizophrenia].

OBJECTIVE: To explore the roles of diffusion tensor imaging (DTI) of white matter at an early stage of schizophrenia. METHODS: The participants were 20 first-episode, medication-naïve schizophrenics at an early stage (1 - 6 months) and 20 healthy controls adjusted in gender and age during December 2009 and October 2010. They underwent diffusion weighted magnetic resonance imaging with a single-shot echo planar imaging (EPI) sequence aligned to straight axial plane. The fractional anisotropy (FA) images of two groups underwent two-sample paired t-test with SPM5 software. RESULTS: The schizophrenics at an early stage demonstrated a significant decrease of regional white matter FA values in right anterior cingulated (MNI: x = 12, y = 24, z = -10; cluster = 145) and right middle occipital lobe (MNI: x = 36, y = -76, z = -2; cluster = 135). CONCLUSION: The altered white matter DTI in right anterior cingulated and middle occipital lobe may contribute to an early detection of schizophrenia.

Design and analysis of welding inspection robot.

Periodic inspection, commonly performed by a technician, of weld seam quality is important for assessing equipment reliability. To save labor costs and improve efficiency, an autonomous navigation and inspection robot is developed. The development process involves the design of chassis damping, target detection mechanism, control system, and algorithms. For performing weld inspection in complex, outdoor, environments, an algorithm is developed for the robot to avoid any obstacles. This algorithm for planning the inspection route is based on an improved timed-elastic-band (TEB) algorithm. The developed robot is capable of conducting inspection tasks in complex and dangerous environments efficiently and autonomously.

[Diffusion tensor imaging findings in first-episode and chronic schizophrenics].

OBJECTIVE: To investigate the integrity of white matters in first-episode and chronic schizophrenics. METHODS: For this study, 39 first-episode and 38 chronic schizophrenics, 69 healthy controls (age, gender and years of received education no significantly different from those of the patients) underwent diffusion weighted images with a single-shot echo planar imaging (EPI) sequence aligned to the straight axial plane. The fractional anisotropy (FA) images of three groups underwent one-way ANOVA with the methods of voxel-based morphometric (VBM) analysis. RESULTS: (1) There were three brain regions where the FA values of white matter were different among three groups: right caudate nucleus (MNI: 20, 12, 14; cluster = 432 voxels; FA value: 0.36 ± 0.18 vs 0.35 ± 0.24 vs 0.38 ± 0.17), left insula (MNI: -32, 18, 2; cluster = 204 voxels; FA value: 0.35 ± 0.31 vs 0.33 ± 0.24 vs 0.36 ± 0.21) and right anterior cingulate (MNI: 16, 36, 12; cluster = 132 voxels; FA value: 0.35 ± 0.29 vs 0.34 ± 0.31 vs 0.37 ± 0.25). (2) The mean FA values of the three brain regions of two patients groups decreased versus those of healthy controls (P < 0.05). (3) The mean FA values of left insular region in chronic patients decreased versus those of the first-episode patients (P < 0.05). CONCLUSION: The reduced integrity of white matter may play an etiological role in schizophrenia and the changes are probably progressive.

[Comparison of white matter integrity of schizophrenic patients with and without impulsive behaviors by diffusion tensor magnetic resonance imaging].

OBJECTIVE: To compare the regional white matter integrity of schizophrenics with impulsive behaviors versus those without. METHODS: Seventeen patients with first-episode-schizophrenia impulsive behaviors and 24 patients with first-episode-schizophrenia non-impulsive behaviors underwent diffusion weighted magnetic resonance imaging with a single-shot echo planar imaging (EPI) sequence aligned to straight axial plane. The fractional anisotropy (FA) images of two groups received two-sample t-test with SPM5 software. RESULTS: The patients with impulsive behaviors demonstrated a significant decrement of white matter FA values in left precentral gyrus (MNI: x = -28.00, y = -28.72, z = -54.71; cluster = 79 voxels), left cerebellum anterior lobe (MNI: x = -22, y = -56, z = -28; cluster = 130 voxels) and left occipital lobe (MNI: x = -6, y = -72, z = 6; cluster = 54 voxels). CONCLUSION: The altered white matter integrity of left precentral gyrus, cerebellum anterior lobe and occipital lobe may be involved in the neural mechanism of impulsive behaviors in schizophrenia.

Effect of the Interaction between Depression and Sleep Disorders on the Stroke Occurrence: An Analysis Based on National Health and Nutritional Examination Survey.

OBJECTIVE: To investigate the effect of the interaction between depression and sleep disorders on the stroke occurrence based on the data from the National Health and Nutritional Examination Survey (NHANES). METHODS: Seven cycles of 2-year NHANES data (2005-2018) were analyzed in this study. Univariate analysis was first performed between the stroke and nonstroke patients, and then, multivariate logistic regression models were conducted to analyze the association of depression, sleep disorders, and their interactions with stroke occurrence. RESULTS: A total of 30473 eligible participants were included in this study, including 1138 (3.73%) with stroke and 29335 (96.27%) with nonstroke. Except sex, the differences were all significant between the stroke and nonstroke patients in baseline information (all P < 0.001). Depression (odds ratio (OR): 2.494, 95% confidence interval (CI): 2.098-2.964), depression severity (moderate, OR: 2.013, 95% CI: 1.612-2.514; moderately severe, OR: 2.598, 95% CI: 1.930-3.496; severe, OR: 5.588, 95% CI: 3.883-8.043), and sleep disorders (OR: 1.677, 95% CI: 1.472-1.910) were presented to be associated with an increased risk of stroke after correcting all the confounders. The logistic regression analysis showed that there was a synergic, additive interaction between depression and sleep disorders on the stroke occurrence, and the proportion of stroke patients caused by this interaction accounted for 27.1% of all the stroke patients. CONCLUSION: Depression, depression severity, and sleep disorders are all independently associated with a high risk of stroke. The interaction between depression and sleep disorders can synergistically increase the stroke occurrence.

Effect of Initial Microstructure on the Toughness of Coarse-Grained Heat-Affected Zone in a Microalloyed Steel.

Toughness of the coarse-grained-heat-affected-zone (CGHAZ) strongly depends on the prior austenite grain size. The prior austenite grain size is affected not only by chemical composition, thermal cycle, and dissolution of second-phase particles, but also by the initial microstructure. The effect of base metal microstructure (ferrite/pearlite obtained by air cooling and martensite obtained by water-quenching) on Charpy impact toughness of the CGHAZ has been investigated for different heat inputs for high-heat input welding of a microalloyed steel. A welding thermal cycle with a heat input of 100 kJ/cm and 400 kJ/cm were simulated on the MMS-300 system. Despite a similar microstructure in the CGHAZ of both the base metals, the average Charpy impact energy for the air-cooled base metal was found to be higher than the water-quenched base metal. Through thermo-kinetic simulations, it was found that a higher enrichment of Mn/C at the ferrite/austenite transformation interface of the CGHAZ of water-quenched base metal resulted in stabilizing austenite at a lower A1 temperature, which resulted in a coarser austenite grain size and eventually lowering the toughness of the CGHAZ.

Specific white matter connectomic changes in schizophrenia compared with psychotic bipolar disorder.

BACKGROUND: Schizophrenia (SZ) and bipolar disorder with psychosis (BDP) can be clinically confusing. The specific connectomic changes in SZ compared with BDP may lead to a deeper comprehension of the pathophysiological core of SZ. Therefore, this study explored the common and distinct white matter (WM) structural connectomic alterations between these two diseases. METHOD: Diffusion tensor imaging data were collected from 19 drug-naïve patients with first episode SZ, 19 drug-naïve patients with BDP, and 19 healthy controls (HC). A graph theoretical approach was used to assess the brain WM network properties. RESULTS: Except for the clustering coefficients, no significant differences in the global parameters was found between SZ and BDP. Five brain regions, the right precentral, right post-cingulum, right insula, left superior occipital, and left inferior temporal gyri, showed specific differences in the nodal parameters in SZ compared with BDP and HC. Nine brain regions, the left rectus, left lingual, right inferior parietal, left superior temporal, right precentral, right postcentral, bilateral middle frontal, and right post-cingulum gyri, showed specific differences in the nodal parameters in BDP. Significant correlations between clinical symptoms and connectomic changes were detected in the right insula and left superior occipital gyrus in patients with SZ but in the left lingual gyrus in patients with BDP. CONCLUSIONS: Identifying shared and distinct WM structural networks between SZ and BDP may improve the understanding of the neuroanatomy of mental diseases. Specifically, the insula, the inferior temporal, superior temporal, and the lingual gyri may help to distinguish between SZ and BDP.

Cascading phase transformations in high carbon steel resulting in the formation of inverse bainite: An atomic scale investigation.

Atom probe tomography (APT) has been used to understand the redistribution of solutes during the isothermal cascading phase transformations from supersaturated austenite resulting in the formation of inverse bainite. Different cascading reactions resulting in the formation of inverse bainite, namely the cementite midrib formation, ferrite formation, secondary cementite formation, and the degenerated microstructure of inverse bainite have been studied in detail. Solute profiles across the different transformation interfaces indicate Negligible Partitioning Local Equilibrium (NPLE) type growth kinetics for cementite midrib, whereas a transition in growth kinetics from Para Equilibrium (PE) to Negligible Partitioning Local Equilibrium (NPLE) is observed for secondary cementite and ferrite transformation. The results provide a strong indication that the inverse bainitic transformation occurs as a consequence of individual cascading phase transformations starting from parent austenite, and the transformation of inverse bainite occurs in a similar manner to Widmanstatten ferrite/bainitic ferrite with carbon diffusion-controlled growth, and without any reconstructive or long-range diffusion of substitutional solutes.

Factors related to duration of untreated psychosis of first episode schizophrenia spectrum disorder.

AIM: Duration of untreated psychosis (DUP) is associated with outcome and functioning. It is expected that scientists will find factors that modulate DUP, but thus far, research on this topic has shown inconsistent results. Furthermore, similar studies in China are insufficient. This study aims to explore social and clinical factors for DUP in South China and to learn the influence that family plays on DUP through their awareness of psychosis. METHODS: Participants included 216 patients with first episode schizophrenia spectrum disorder. The Nottingham Onset Schedule was used to assess DUP. The relationship between DUP and social and clinical characteristics were then analysed by correlation analysis, survival analysis and Cox regression analysis. The awareness of the patient's family for the cause of psychosis, the reason for treatment and the cause for delay of treatment were investigated using a questionnaire. RESULTS: The median DUP was 64.5 days. Insidious onset and being unemployed were found to be risk factors for a long DUP. The family attributed the main cause of psychosis to stress. The main cause for the delay of treatment was because families misjudged the patients' disease. More family members of long DUP patients compared to short DUP patients thought the causes were due to ideological problems or puberty, rather than to mental health. CONCLUSION: The results of this study indicated that some social or clinical characteristics influence DUP. The family's awareness plays an important role when seeking help. To reduce DUP, the public needs more knowledge of mental illness.

Disrupted brain anatomical connectivity in medication-naïve patients with first-episode schizophrenia.

Previous studies suggested that the topological properties of brain anatomical networks may be aberrant in schizophrenia (SCZ), and most of them focused on the chronic and antipsychotic-medicated SCZ patients which may introduce various confounding factors due to antipsychotic medication and duration of illness. To avoid those potential confounders, a desirable approach is to select medication-naïve, first-episode schizophrenia (FE-SCZ) patients. In this study, we acquired diffusion tensor imaging datasets from 30 FE-SCZ patients and 34 age- and gender-matched healthy controls. Taking a distinct gray matter region as a node, inter-regional connectivity as edge and the corresponding streamline counts as edge weight, we constructed whole-brain anatomical networks for both groups, calculated their topological parameters using graph theory, and compared their between-group differences using nonparametric permutation tests. In addition, network-based statistic method was utilized to identify inter-regional connections which were impaired in the FE-SCZ patients. We detected only significantly decreased inter-regional connections in the FE-SCZ patients compared to the controls. These connections were primarily located in the frontal, parietal, occipital, and subcortical regions. Although small-worldness was conserved in the FE-SCZ patients, we found that the network strength and global efficiency as well as the degree were significantly decreased, and shortest path length was significantly increased in the FE-SCZ patients compared to the controls. Most of the regions that showed significantly decreased nodal parameters belonged to the top-down control, sensorimotor, basal ganglia, and limbic-visual system systems. Correlation analysis indicated that the nodal efficiency in the sensorimotor system was negatively correlated with the severity of psychosis symptoms in the FE-SCZ patients. Our results suggest that the network organization is changed in the early stages of the SCZ disease process. Our findings provide useful information for further understanding the brain white matter dysconnectivity of schizophrenia.

No association of ZNF804A rs1344706 with white matter integrity in schizophrenia: a tract-based spatial statistics study.

Altered brain connectivity has been widely considered as a genetic risk mechanism for schizophrenia. Of the many susceptibility genes identified so far, ZNF804A (rs1344706) is the first common genetic variant associated with schizophrenia on a genome-wide level. Previous fMRI studies have found that carriers of rs1344706 exhibit altered functional connectivity. However, the relationship between ZNF804A and white matter structural connectivity in patients of schizophrenia remains unknown. In this study, 100 patients with schizophrenia and 69 healthy controls were genotyped at the single nucleotide polymorphism rs1344706. Diffusion tensor imaging (DTI) was conducted and analyzed with tract-based spatial statistics. Systematic statistical analysis was conducted on multiple diffusion indices, including fractional anisotropy, axial diffusivity, radial diffusivity, and mean diffusivity. Unpaired two-sample t-test revealed significant differences in fractional anisotropy and diffusivity between schizophrenia and control groups. A two-way ANOVA analysis was conducted to assess the main effects of and the interaction between schizophrenia and ZNF804A. Although significant main effects of the diagnosis of schizophrenia were found on radial diffusivity, no association between the ZNF804A (rs1344706) and white matter connectivity was found in the entire group of subjects or in a selected subgroup of age-matched subjects (n=72).

Association of the ZNF804A gene polymorphism rs1344706 with white matter density changes in Chinese schizophrenia.

BACKGROUND: ZNF804A gene polymorphism rs1344706, the first genetic risk variant to achieve genome wide significance for schizophrenia, has been linked to neural functional connectivity. Dysconnectivity of WM may be the primary pathological mechanism of schizophrenia. Association of this variant with regional WM density has not been investigated in schizophrenic patients. METHODS: 69 healthy controls and 80 patients with schizophrenia underwent genotyping of rs1344706 SNPs, and were examined for WM density (T1-weighted MRI). The association of rs1344706 with WM changes in schizophrenia patients and healthy controls was analyzed using a full-factorial 2×2 analysis of variance. RESULTS: 1. There was an interaction on WM density in the left prefrontal lobe between the rs1344706 genotype and schizophrenic diagnosis, where the risk T allele carriers presented higher WM density in the schizophrenia patients and lower WM density in healthy controls in comparison with the non-risk allele carriers. 2. The risk allele was associated with an increased WM density of the bilateral hippocampus in both the patients and the healthy group. LIMITATION: The influence of antipsychotics to the white matter in schizophrenic patients was not fully eliminated. CONCLUSIONS: The ZNF804A variant may confer risk for schizophrenia by exerting its effects on the WM in the left prefrontal lobe together with other risk factors for schizophrenia.