A Selective Review on Information Criteria in Multiple Change Point Detection.

Change points indicate significant shifts in the statistical properties in data streams at some time points. Detecting change points efficiently and effectively are essential for us to understand the underlying data-generating mechanism in modern data streams with versatile parameter-varying patterns. However, it becomes a highly challenging problem to locate multiple change points in the noisy data. Although the Bayesian information criterion has been proven to be an effective way of selecting multiple change points in an asymptotical sense, its finite sample performance could be deficient. In this article, we have reviewed a list of information criterion-based methods for multiple change point detection, including Akaike information criterion, Bayesian information criterion, minimum description length, and their variants, with the emphasis on their practical applications. Simulation studies are conducted to investigate the actual performance of different information criteria in detecting multiple change points with possible model mis-specification for the practitioners. A case study on the SCADA signals of wind turbines is conducted to demonstrate the actual change point detection power of different information criteria. Finally, some key challenges in the development and application of multiple change point detection are presented for future research work.

Integrated microRNA and whole-transcriptome sequencing reveals the involvement of small and long non-coding RNAs in the fiber growth of ramie plant.

BACKGROUND: MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are the two main types of non-coding RNAs that play crucial roles in plant growth and development. However, their specific roles in the fiber growth of ramie plant (Boehmeria nivea L. Gaud) remain largely unknown. METHODS: In this study, we performed miRNA and whole-transcriptome sequencing of two stem bark sections exhibiting different fiber growth stages to determine the expression profiles of miRNAs, lncRNAs, and protein-encoding genes. RESULTS: Among the identified 378 miRNAs and 6,839 lncRNAs, 88 miRNAs and 1,288 lncRNAs exhibited differential expression. Bioinformatics analysis revealed that 29 and 228 differentially expressed protein-encoding genes were targeted by differentially expressed miRNAs and lncRNAs, respectively, constituting eight putative competing endogenous RNA networks. lncR00022274 exhibited downregulated expression in barks with growing fibers. It also had an antisense overlap with the MYB gene, BntWG10016451, whose overexpression drastically increased the xylem fiber number and secondary wall thickness of fibers in the stems of transgenic Arabidopsis, suggesting the potential association of lncR00022274-BntWG10016451 expression with fiber growth. CONCLUSIONS: These findings provide insights into the roles of ncRNAs in the regulation of fiber growth in ramie, which can be used for the biotechnological improvement of its fiber yield and quality in the future.

A phase 1 trial of fuzuloparib in combination with apatinib for advanced ovarian and triple-negative breast cancer: efficacy, safety, pharmacokinetics and germline BRCA mutation analysis.

BACKGROUND: The effect of the combination of an anti-angiogenic agent with a poly (ADP-ribose) polymerase (PARP) inhibitor in cancer treatment is unclear. We assessed the oral combination of fuzuloparib, a PARP inhibitor, and apatinib, a VEGFR2 inhibitor for treating advanced ovarian cancer (OC) or triple-negative breast cancer (TNBC). METHODS: This dose-escalation and pharmacokinetics-expansion phase 1 trial was conducted in China. We used a standard 3 + 3 dose-escalation design, with 7 dose levels tested. Patients received fuzuloparib orally twice daily, and apatinib orally once daily. The study objectives were to determine the safety profile, recommended phase 2 dose (RP2D), pharmacokinetics, preliminary efficacy, and efficacy in relation to germline BRCA mutation (gBRCAmut). RESULTS: Fifty-two pre-treated patients were enrolled (30 OC/22 TNBC). 5 (9.6%) patients had complete response, 14 (26.9%) had partial response, and 15 (28.8%) had stable disease. Objective response rate (ORR) and disease control rate were 36.5% (95% CI 23.6-51.0) and 65.4% (95% CI 50.9-78.0), respectively. At the highest dose level of fuzuloparib 100 mg plus apatinib 500 mg, the ORR was 50.0% (4/8; 95% CI 15.7-84.3); this dose was determined to be the RP2D. Patients with gBRCAmut had higher ORR and longer median progression-free survival (PFS) than those with gBRCAwt, both in OC (ORR, 62.5% [5/8] vs 40.9% [9/22]; PFS, 9.4 vs 6.7 months) and TNBC (ORR, 66.7% [2/3] vs 15.8% [3/19]; PFS, 5.6 vs 2.8 months). Two dose-limiting toxicities occurred: grade 4 febrile neutropenia (fuzuloparib 100 mg plus apatinib 250 mg) and thrombocytopenia (fuzuloparib 100 mg plus apatinib 375 mg). Maximum tolerated dose was not reached. The most common treatment-related grade ≥ 3 toxicities in all patients were hypertension (19.2%), anaemia (13.5%), and decreased platelet count (5.8%). Exposure of apatinib increased proportionally with increasing dose ranging from 250 to 500 mg, when combined with fuzuloparib 100 mg. CONCLUSIONS: Fuzuloparib plus apatinib had acceptable safety in patients with advanced OC or TNBC. Fuzuloparib 100 mg bid plus apatinib 500 mg qd was established as the RP2D. With the promising clinical activity observed, this combination is warranted to be further explored as a potential alternative to chemotherapy. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03075462 (Mar. 9, 2017).

Relation between endothelial nitric oxide synthase genetic polymorphisms and pulmonary arterial hypertension in newborns with congenital heart disease.

OBJECTIVE: To investigate whether endothelial nitric oxide synthase (eNOS) rs1799983, rs2070744, and rs61722009 gene polymorphisms are associated with pulmonary arterial hypertension (PAH) in South Fujian newborns with congenital heart disease (CHD). METHODS: Genotyping for the eNOS rs1799983, rs2070744, and rs61722009 polymorphisms was performed using Sanger sequencing in 50 newborns with PAH secondary to CHD [CHD PAH (+)], 52 newborns with CHD without PAH [CHD PAH (-)], and 60 healthy controls. RESULTS: The genotype and allele frequency distributions of eNOS rs1799983, rs2070744, and rs61722009 were similar between CHD and healthy controls (P > .05). The frequencies of the eNOS rs1799983 G/T allele were 85% and 15% in the CHD PAH (+) group and 96.15% and 3.85% in the CHD PAH (-) group, the frequency of the T allele was higher in the CHD PAH (+) group than in the CHD PAH (-) group(P< .05), and patients with the GT/TT genotypes of eNOS rs1799983 may present higher PAH (OR = 4.412, 95%CI:1.411-13.797, P= .011). Newborns with the GT/TT genotypes had decreased plasma NO production compared to newborns with the GG genotype (P< .01), and NO levels in the CHD PAH (+) group were significantly lower than those in the CHD PAH (-) group (P < .05). CONCLUSION: The T allele could be a risk factor for PAH in newborns with CHD in South Fujian through decreased levels of nitric oxide production by the endothelium.

[PreS1 Antigen of HBV Down-Regulates MHC-â on the Surface of Hepatocytes and Promotes Hepatocarcinogenesis].

Objective: To explore the internal mechanism of hepatocellular carcinoma (HCC) induced by chronic hepatitis B virus (HBV) infection. Methods: L02, HepG2 and Huh7 cells stably overexpressing HBV preS1 antigen were analyzed by flow cytometry, qRT-PCR and tumorigenesis in nude mice to evaluate the effect of preS1 antigen in HBV-related hepatocarcinogenesis. Results: Our results showed that the expression of cancer stem cell (CSCs) related factors and cell surface markers in preS1 overexpressing cells were up-regulated, and the tumorigenicity of these cells was enhanced in nude mice. In addition, preS1 overexpression could down-regulate the expression of major histocompatibility complex Ⅰ (MHC-Ⅰ). The expression of MHC-Ⅰ on the cell surface could be restored by adding interferon gamma (IFN-γ) in the process of cell culturing and the tumorigenicity of cells in nude mice could thus be reduced. Conclusion: Based on the above results, we believe that preS1 is a carcinogen of HBV and that it promotes the formation of liver cancer through down regulating MHC-Ⅰ on the surface of hepatocytes.

Efficacy and safety of general anesthesia deep brain stimulation for dystonia: an individual patient data meta-analysis of 341 cases.

OBJECTIVE: The efficacy and safety of deep brain stimulation (DBS) under general anesthesia for the treatment of dystonia have not yet been confirmed with high level of evidence. This meta-analysis with pooled individual patient data aims to assess the clinical outcomes and identify the potential prognostic factors of dystonia patients who underwent general anesthesia DBS. METHODS: We searched PubMed, Web of Science, and Embase for articles describing patients with dystonia who underwent asleep DBS and had individual Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) scores. The relative improvement in BFMDRS scores was considered the primary outcome. Pearson correlation analyses and multivariate linear regression analysis were conducted to explore the prognostic factors. RESULTS: A total of 34 studies involving 341 patients were included. The mean postoperative improvement in BFMDRS-M (BFMDRS movement subscale) and BFMDRS-D (BFMDRS disability subscale) scores were 58.6±36.2% and 48.5±38.7% at the last follow-up visit, respectively, with a mean follow-up time of 22.4±27.6 months. Age at surgery and disease duration showed a negative correlation with the percent improvement of BFMDRS-M (%) at the last visit (r=-0.134, P=0.013; r=-0.165, P=0.006). In the stepwise multivariate regression, only disease duration remained a relevant factor. Additionally, the adverse events were acceptable. CONCLUSION: General anesthesia DBS is a safe, effective, and feasible option for dystonia patients in the long term. Shorter disease duration predicts better clinical outcomes.

Similar Long-Term Clinical Outcomes of Deep Brain Stimulation With Different Electrode Targets for Primary Meige Syndrome: One Institution's Experience of 17 Cases.

OBJECTIVE: Deep brain stimulation (DBS) is considered an effective and safe treatment for patients with primary Meige syndrome (MS). Both the subthalamic nucleus (STN) and globus pallidus pars internus (Gpi) have been shown to be optional targets for electrode implantation to improve clinical symptoms, but the relationship between clinical outcomes and target is still unclear. The current study aims to compare the clinical outcomes of DBS with different electrode targets for primary MS. MATERIALS AND METHODS: We performed a retrospective study to assess the clinical outcomes for 17 consecutive patients with primary MS in Wuhan Union Hospital from January 2016 to September 2019. Six patients were treated by Gpi-DBS and 11 patients were treated by STN-DBS. All patients were assessed before surgery and at the last follow-up after surgery. The Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) including the movement and disability scales was used to evaluate the dystonia severity of the eyes, the mouth, speech, and swallowing. The median follow-up duration was 30.1 ± 13.1 months (range 6 months-52 months). RESULTS: In our study, DBS improved the BFMDRS-M scores by 70.52 ± 7.45% and the BFMDRS-D scores by 70.51 ± 8.38% for patients with MS. STN-DBS and Gpi-DBS had similar effects not only on the BFMDRS-M and BFMDRS-D scores, but also on the subitems including eyes, mouth, speech, and swallowing. The stimulation voltage for the Gpi was significantly higher than that for the STN. The improvements were similar in the general anesthesia and local anesthesia groups (p > 0.05). CONCLUSION: The curative effects of STN-DBS and Gpi-DBS on patients with primary MS are similar. Both the STN and Gpi could be effective targets of DBS for primary MS.

1,3-Dipolar Cycloaddition between Dehydroalanines and C,N-Cyclic Azomethine Imines: Application to Late-Stage Peptide Modification.

A non-catalytic, mild, and easy-to-handle protecting group switched 1,3-dipolar cycloaddition (1,3-DC) between bi- or mono-N-protected Dha and C,N-cyclic azomethine imines, which afford various quaternary amino acids with diverse scaffolds, is disclosed. Specifically, normal-electron-demand 1,3-DC reaction occurs between bi-N-protected Dha and C,N-cyclic azomethine imines, while inverse-electron-demand 1,3-DC reaction occurs between mono-N-protected Dha and C,N-cyclic azomethine imines. Above all, the reactions can be carried out between peptides with Dha residues at the position of interest and C,N-cyclic azomethine imines, both in homogeneous phase and on resins in SPPS. It provides a new toolkit for late-stage peptide modification, labeling, and peptide-drug conjugation. To shed light on the high regioselectivity of the reaction, DFT calculations were carried out, which were qualitatively consistent with the experimental observations.

A genomic resource derived from the integration of genome sequences, expressed transcripts and genetic markers in ramie.

BACKGROUND: The redundancy of genomic resources, including transcript and molecular markers, and their uncertain position in the genome have dramatically hindered the study of traits in ramie, an important natural fiber crop. RESULTS: We obtained a high-quality transcriptome consisting of 30,591 non-redundant transcripts using single-molecule long-read sequencing and proposed it as a universal ramie transcriptome. Additionally, 55,882 single nucleotide polymorphisms (SNPs) were identified and a high-density genetic map was developed. Based on this genetic map, 181.7 Mb ramie genome sequences were assembled into 14 chromosomes. For the convenient use of these resources, 29,286 (~ 95.7%) of the transcripts and all 55,882 SNPs, along with 1827 previously reported sequence repeat markers (SSRs), were mapped into the ramie genome, and 22,343 (~ 73.0%) transcripts, 50,154 (~ 89.7%) SNPs, and 1466 (~ 80.3%) SSRs were assigned to a specific location in the corresponding chromosome. CONCLUSION: This is the first study to characterize the ramie transcriptome by long-read sequencing, and the substantial number of transcripts of significant length obtained will accelerate our understanding of ramie growth and development. This integration of genome sequences, expressed transcripts, and genetic markers will provide an extremely useful resource for genetic, molecular, and breeding studies of ramie.

Protective effect of peptide DR8 on bleomycin-induced pulmonary fibrosis by regulating the TGF-ß/MAPK signaling pathway and oxidative stress.

Pulmonary fibrosis (PF) is a fatal and irreversible lung disease that eventually causes respiratory failure, lung dysfunction and death. The peptide DHNNPQIR-NH2 (DR8) has been reported to possess potent antioxidant activity, and an imbalance of oxidation/antioxidation is a crucial mechanism that causes PF. Here, we studied the ability of DR8 to improve PF and further explored the pathway in which DR8 plays a critical role. We found that after prophylactic or therapeutic treatment with DR8, fibrosis-associated indices, including marker proteins, proinflammatory cytokines and profibrogenic cytokines, were significantly downregulated. Importantly, DR8 could reduce bleomycin-induced pathological changes and collagen deposition, especially collagen I content. Furthermore, DR8 prominently upregulated nonenzymatic antioxidants and enzymatic antioxidants. Consistent with the in vivo results, we observed that DR8 significantly inhibited the proliferation and reactive oxygen species (ROS) generation of A549 cells and NIH3T3 cells stimulated with transforming growth factor-ß1 (TGF-ß1), as well as decreased NADPH oxidase 4 (NOX4) levels under the same conditions. Moreover, DR8 reversed the TGF-ß1-induced upregulation of phosphorylated ERK1/2 and p38 MAPK in cells and the bleomycin-induced upregulation of these indices in mice. Our results indicate that DR8 could prevent and treat PF by reducing oxidative damage and suppressing the TGF-ß/MAPK pathway. Because of the high efficiency and low toxicity of DR8, we consider that DR8 could be a candidate drug for PF, and our studies establish a foundation for the development of a lead compound to be used as a therapy for fibrosis-related diseases.

Rhein induces apoptosis and autophagy in human and rat glioma cells and mediates cell differentiation by ERK inhibition.

In this study, we investigated the anticancer potentials of Rhein, an anthraquinone derivative of most commonly used Chinese rhubarb on the rat F98 glioma cells. The experimental studies revealed that Rhein induced cell cycle arrest, caspase mediated apoptosis. It results in the formation of intracellular acidic vesicles in cytoplasm, leading to autophagy. Differentiation of viable cells towards elongation of matured astrocytes was proved by monitoring dramatic changes in morphological characteristics as well as identified from the elevation of glial fibrillary acidic protein (GFAP) expression. Rhein treatment did not alter the phosphorylated MAPKs activation including p-38, JNK and NF-κB, transcription unit whereas rhein significantly inhibited ERK1/2 activation in F98 glioma cells. PD98059, a specific inhibitor for ERK activation imitates rhein effects on morphology and expressions of GFAP but did not help to induce any apoptosis or autophagy. Collective data exhibited that potentials of rhein in anti-cancer property in ERK-independent apoptosis and autophagy in association with downregulated ERK-dependent differentiation process of glioma cell lines.

On-Line Corrosion Monitoring of Plate Structures Based on Guided Wave Tomography Using Piezoelectric Sensors.

Corrosion is a major safety and economic concern to various industries. In this paper, a novel ultrasonic guided wave tomography (GWT) system based on self-designed piezoelectric sensors is presented for on-line corrosion monitoring of large plate-like structures. Accurate thickness reconstruction of corrosion damages is achieved by using the dispersive regimes of selected guided waves and a reconstruction algorithm based on full waveform inversion (FWI). The system makes use of an array of miniaturised piezoelectric transducers that are capable of exciting and receiving highly dispersive A0 Lamb wave mode at low frequencies. The scattering from transducer array has been found to have a small effect on the thickness reconstruction. The efficiency and the accuracy of the new system have been demonstrated through continuous forced corrosion experiments. The FWI reconstructed thicknesses show good agreement with analytical predictions obtained by Faraday's law and laser measurements, and more importantly, the thickness images closely resemble the actual corrosion sites.

Newly recognized orbital malformations in kabuki syndrome: A case report.

Kabuki syndrome (KS) is a rare congenital disorder with distinctive characteristics. Herein, we describe a KS patient carrying a novel mutation in the KMT2D gene, c.11785C > T (p.Gln3929*). The patient presented with typical eyelid deformities, including eversion of the lateral lower eyelids, long palpebral fissures, hypertelorism, and medial epicanthus. Orbital computed tomography revealed orbital bone malformation with temporally and inferiorly displaced zygomatic bone. The bilateral orbits were shallow with an enlarged angle between the lateral walls. Zygomatic and maxillary bone dysplasia were also observed. Orbital bone anomalies are thought to be one of the characteristics of KS.

Advances in artificial intelligence in thyroid-associated ophthalmopathy.

Thyroid-associated ophthalmopathy (TAO), also referred to as Graves' ophthalmopathy, is a medical condition wherein ocular complications arise due to autoimmune thyroid illness. The diagnosis of TAO, reliant on imaging, typical ocular symptoms, and abnormalities in thyroid function or thyroid-associated antibodies, is generally graded and staged. In recent years, Artificial intelligence(AI), particularly deep learning(DL) technology, has gained widespread use in the diagnosis and treatment of ophthalmic diseases. This paper presents a discussion on specific studies involving AI, specifically DL, in the context of TAO, highlighting their applications in TAO diagnosis, staging, grading, and treatment decisions. Additionally, it addresses certain limitations in AI research on TAO and potential future directions for the field.

Thermodynamics-Guided High-Throughput Discovery of Eutectic High-Entropy Alloys for Rapid Solidification.

Excellent castability, significantly refined microstructure, and good mechanical properties make eutectic high-entropy alloys (EHEAs) a natural fit for rapid solidification processes, e.g., additive manufacturing. Previous investigations have focused on developing EHEAs through trial and error and mixing known binary eutectic materials. However, eutectic compositions obtained from near-equilibrium conditions do not guarantee a fully eutectic microstructure under rapid solidifications. In this work, a thermodynamically guided high-throughput framework is proposed to design EHEAs for rapid solidification. Empirical formulas derived from past experimental observations and thermodynamic computations are applied and considered phase growth kinetics under rapid solidification (skewed phase diagram). The designed alloy candidate, Co25.6Fe17.9Ni22.4Cr19.1Ta8.9Al6.1 (wt.%), contains nanostructured eutectic lamellar and shows a high Vickers hardness of 675 Hv. In addition to this specific composition, the alloy design toolbox enables the development of new EHEAs for rapid solidification without the limitation of previous knowledge.

An ensemble deep learning diagnostic system for determining Clinical Activity Scores in thyroid-associated ophthalmopathy: integrating multi-view multimodal images from anterior segment slit-lamp photographs and facial images.

Background: Thyroid-associated ophthalmopathy (TAO) is the most prevalent autoimmune orbital condition, significantly impacting patients' appearance and quality of life. Early and accurate identification of active TAO along with timely treatment can enhance prognosis and reduce the occurrence of severe cases. Although the Clinical Activity Score (CAS) serves as an effective assessment system for TAO, it is susceptible to assessor experience bias. This study aimed to develop an ensemble deep learning system that combines anterior segment slit-lamp photographs of patients with facial images to simulate expert assessment of TAO. Method: The study included 156 patients with TAO who underwent detailed diagnosis and treatment at Shanxi Eye Hospital Affiliated to Shanxi Medical University from May 2020 to September 2023. Anterior segment slit-lamp photographs and facial images were used as different modalities and analyzed from multiple perspectives. Two ophthalmologists with more than 10 years of clinical experience independently determined the reference CAS for each image. An ensemble deep learning model based on the residual network was constructed under supervised learning to predict five key inflammatory signs (redness of the eyelids and conjunctiva, and swelling of the eyelids, conjunctiva, and caruncle or plica) associated with TAO, and to integrate these objective signs with two subjective symptoms (spontaneous retrobulbar pain and pain on attempted upward or downward gaze) in order to assess TAO activity. Results: The proposed model achieved 0.906 accuracy, 0.833 specificity, 0.906 precision, 0.906 recall, and 0.906 F1-score in active TAO diagnosis, demonstrating advanced performance in predicting CAS and TAO activity signs compared to conventional single-view unimodal approaches. The integration of multiple views and modalities, encompassing both anterior segment slit-lamp photographs and facial images, significantly improved the prediction accuracy of the model for TAO activity and CAS. Conclusion: The ensemble multi-view multimodal deep learning system developed in this study can more accurately assess the clinical activity of TAO than traditional methods that solely rely on facial images. This innovative approach is intended to enhance the efficiency of TAO activity assessment, providing a novel means for its comprehensive, early, and precise evaluation.

Injectable temperature-sensitive hydrogel facilitating endoscopic submucosal dissection.

Purpose: Early gastrointestinal tumors can be removed by endoscopic procedures. Endoscopic mucosal dissection (ESD) requires submucosal fluid injection to provide mucosal elevation and prevent intraoperative perforation. However, the clinically applied normal saline mucosal elevation height is low for a short time, which often requires multiple intraoperative injections that increase the inconvenience and procedure time. In addition, recently researched submucosal injection materials (SIM) suffer from complex preparation, poor economy, and poor biocompatibility. Therefore, there is an urgent need for a new type of SIM that can provide long, safe and effective mucosal elevation in support of the endoscopic procedures. Methods: The FS hydrogel is based on polyethylene-polypropylene glycol (F-127) mixed with sodium alginate (SA). The different physicochemical properties of FS hydrogels were characterized through various experiments. Afterward, various biosafety assessments were carried out. Finally, the performance of FS hydrogels was evaluated by in vitro submucosal injection and in vivo swine ESD. Results: The experimental results show that the FS hydrogel is liquid at room temperature, making it easy to inject, and when injected under the mucosa, it undergoes temperature-induced cross-linking, transforming from a liquid to a solid state to provide long-lasting mucosal augmentation. At the same time, the FS hydrogel exhibits controllable gelation, stability, and biocompatibility. The results of in vitro submucosal injections and in vivo ESD procedures showed that FS achieves high mucosal augmentation and provides good submucosal cushioning in the long term. Conclusion: In summary, the F-127/SA hydrogel is simple to synthesize, cost-effective, safe, easy to store, and able to assist ESD well from the perspective of practical clinical problems, indicating that the FS hydrogel can be an ideal potent submucosal injection substitution.

A multi-GPU and CUDA-aware MPI-based spectral element formulation for ultrasonic wave propagation in solid media.

In this paper, we introduce a new multi-GPU-based spectral element (SE) formulation for simulating ultrasonic wave propagation in solids. To maximize communication efficiency, we purposely developed, based on CUDA-aware MPI, two novel message exchange strategies which allow the common nodal forces of different subdomains to be shared between different GPUs in a direct manner, as opposed to via CPU hosts, during central difference-based time integration steps. The new multi-GPU and CUDA-aware MPI-based formulation is benchmarked against a multi-CPU core and classical MPI-based counterpart, demonstrating a remarkable acceleration in each and every stage of the computation of ultrasonic wave propagation, namely matrix assembly, time integration and message exchange. More importantly, both the computational efficiency and the degree-of-freedom limit of the new formulation are actually scalable with the number of GPUs used, potentially allowing larger structures to be computed and higher computational speeds to be realized. Finally, the new formulation was used to simulate the interaction between Lamb waves and randomly shaped thickness loss defects on plates, showing its potential to become an efficient, accurate and robust technique for addressing the propagation of ultrasonic waves in realistic engineering structures.

A refined Lamb wave reciprocity-based method with enhanced sensitivity for damage detection in composite laminates.

The Lamb wave reciprocity-based method is an effective candidate for the health monitoring of composite plates. However, if the damage is located symmetrically between the transmitter-receiver pair, the reciprocity still holds true and the method misjudges its presence. In the present work, a new method for computing the reciprocity index (RI) from Lamb wave signals with extended data length is proposed. This method exploits extra indirect waves that bounce one or more times between the damage and other reflectors. These waves probe the damage through different paths and from different directions. Thus, the damage missed by the direct wave may be exposed by the indirect waves. Benefiting from that, two modified RIs are defined and their performance is validated by two experimental examples. As expected, both indices demonstrate excellent sensitivity to damage even in the middle of the transmitter-receiver pair and ensure a low threshold for the pristine condition, illustrating an excellent ability to distinguish between health and illness.

Ultrasonic defect detection of high-density polyethylene pipe materials using FIR filtering and block-wise singular value decomposition.

Condition monitoring of high-density polyethylene (HDPE) pipes used for fluid and gas transfer is important for the safety of energy conservation and the environment. Ultrasonic phased array imaging methods provide a solution to detect and assess defects in HDPE pipes. However, ultrasonic bulk waves propagating in these viscoelastic media are strongly attenuated, resulting in reduced signal amplitude. In this study, a linear-phase Finite Impulse Response (FIR) filter is used to remove unwanted frequency components from the measured ultrasonic signals to improve the signal-to-noise ratio before applying the imaging algorithm of the total focusing method (TFM). Building upon this, a block-wise singular value decomposition (SVD) technique, which can adaptively determine the singular value cutoff threshold based on each block in the whole TFM image, is used to enhance the obtained TFM image quality. The performance of the combination of FIR filtering and block-wise SVD technique is validated by experimental data of HDPE pipe materials. Results demonstrate that the proposed approach generates good images to provide the detection and characterization of side-drilled holes in HDPE pipe materials.