Fidelity Mechanics: Analogues of the Four Thermodynamic Laws and Landauer's Principle.

Fidelity mechanics is formalized as a framework for investigating critical phenomena in quantum many-body systems. Fidelity temperature is introduced for quantifying quantum fluctuations, which, together with fidelity entropy and fidelity internal energy, constitute three basic state functions in fidelity mechanics, thus enabling us to formulate analogues of the four thermodynamic laws and Landauer's principle at zero temperature. Fidelity flows, which are irreversible, are defined and may be interpreted as an alternative form of renormalization group flows. Thus, fidelity mechanics offers a means to characterize both stable and unstable fixed points: divergent fidelity temperature for unstable fixed points and zero-fidelity temperature and (locally) maximal fidelity entropy for stable fixed points. In addition, fidelity entropy behaves differently at an unstable fixed point for topological phase transitions and at a stable fixed point for topological quantum states of matter. A detailed analysis of fidelity mechanical-state functions is presented for six fundamental models-the quantum spin-1/2 XY model, the transverse-field quantum Ising model in a longitudinal field, the quantum spin-1/2 XYZ model, the quantum spin-1/2 XXZ model in a magnetic field, the quantum spin-1 XYZ model, and the spin-1/2 Kitaev model on a honeycomb lattice for illustrative purposes. We also present an argument to justify why the thermodynamic, psychological/computational, and cosmological arrows of time should align with each other, with the psychological/computational arrow of time being singled out as a master arrow of time.

Excitation of moderate-frequency Love wave in a Plexiglas plate on aluminum semi-space.

Love waves are of great importance in geophysics, electronics, and engineering. Despite intensive studies on high-frequency Love waves for delay lines and chemical/biomedical sensors, moderate-frequency and low-frequency Love waves have seldom been investigated. Here, Love waves in a 2-mm-thick Plexiglas plate bonded on a 50-mm-thick aluminum block were successfully excited and received by using d24 and d15 shear mode PZT wafers. A d31 mode PZT wafer was also employed as the sensor, and results show that no Rayleigh-Lamb type waves were generated. The group velocity curve of the excited Love wave from 120 to 525 kHz matches the theoretical curve well. This work could promote applications of Love waves in many engineering fields.

Risk of Active Pulmonary Tuberculosis among Patients with Coal Workers'Pneumoconiosis: A Case-control Study in China.

The aim of this study was to estimate the association between occupational, environmental, behavioral risk factors, and active pulmonary tuberculosis (PTB) among coal workers' pneumoconiosis (CWP) patients. A matched case-control study was conducted in 86 CWP patients with active PTB and 86 CWP controls without TB. A standardized questionnaire was used for risk factors assessment. Conditioned logistic regression analysis was used to identify associations between the risk factors and active PTB among CWP patients. The results showed that the stage of CWP, poor workplace ventilation, family history of TB, and exposure to TB were independent risk factors for active PTB in patients with CWP with which recommendations for improving work environments, and for case finding activities in patients with CWP could be made.

A Comparative Study of Three Types Shear Mode Piezoelectric Wafers in Shear Horizontal Wave Generation and Reception.

Guided wave-based inspection has emerged as a promising tool to evaluate the reliability of key components in modern industries. The fundamental shear horizontal (SH0) wave is always of great interests for plate-like structures because of its non-dispersion characteristics. However, the generation and reception of SH0 wave using piezoelectric wafers is not straightforward. In this paper, we firstly define three types shear mode piezoelectric wafers, i.e., the conventional in-plane poled thickness-shear (d15) mode, the thickness-poled thickness-shear (d15) mode, and the face-shear (d24) mode. Then, finite element simulations were conducted to demonstrate their performance in SH wave generation and reception. The results indicated that the face shear d24 wafer can generate almost single mode SH0 wave, while both types of d15 wafers would generate Lamb waves and SH0 wave simultaneously. Finally, experiments were carried out to check the efficiency of different shear mode piezoelectric wafers in SH0 wave generation and reception. The results indicated that the d24 wafer can generate and receive SH0 wave of high signal to noise ratio (SNR) with high energy conversion efficiency, while the in-plane poled d15 wafer would generate SH0 wave of high amplitude and acceptable SNR but with relatively low energy conversion efficiency. The performances of thickness-poled d15 wafer was not as good as the other two in both SH wave generation and reception. This work will be helpful for the applications of SH waves in plate-like structures.

Occupational Exposure to Indium of Indium Smelter Workers.

Case reports of indium-related lung disease in workers have raised public concern to the human toxicity of indium (In) and its compounds. However, studies evaluating the exposure or health of workers in In smelting plants are rare. Therefore, in this study, we focused on four In smelting plants, with the main objective of characterizing In in smelter plants in China and discussing the potential exposure biomarkers of In exposure. We recruited 494 subjectsat four In smelting plants in China. Personal air samples, first morning urine and spot blood samples were collected. In concentrations in samples were analyzed using inductively coupled plasma mass spectrometry. In concentrations in air samples did not exceed the permissible concentration-time weighed average, but the smelter workers had a higher internal exposure to In. Positive correlations were observed between the air In and urine In concentrations, and between the air In and blood In concentrations. This study provides basic data for the following In exposure and health risk assessment.

Urbanization and workers' compensation in China from 1995 to 2012.

In order to determine the trend in the number of employees covered by workers' compensation (WC) and trends in the burdens and benefits of WC, and to discuss the possible factors that might influence those trends. A relevant national statistical data from 1995 to 2012 are collected and analyzed. In the results, we found that the proportion of employees covered by WC to total employees in urban areas increased from 13.7% in 1995 to 51.2% in 2012 and also exhibited a significant degree of polarization. In 2012, 27.3% of the peasant workers were covered by WC, which accounted for 37.8% of the total employees covered by WC. Factors found to impact the number of employees covered by WC and trends in the burdens and benefits of WC from 1995 to date in China included urbanization, represented by the migration of farm labor to urban areas, changes in industry mix, regional disparity, GDP movements, and changes to legislation on WC and occupational health and safety. It still has a long way to go to reduce work-related injuries and occupational diseases (ODs) to levels comparable with other industrialized countries.

[Misdiagnosis of pneumoconiosis or silicotuberculosis in China: a pooled analysis of 1178 cases].

OBJECTIVE: To investigate the situation and causes of misdiagnosis of pneumoconiosis or silicotuberculosis in China by pooled analysis, and to provide a reference for the clinical diagnosis of pneumoconiosis in China and reduce the misdiagnosis rate. METHODS: A computer search was performed to collect the studies on the misdiagnosis of pneumoconiosis or silicotuberculosis published in China from 1985 to 2013. The obtained data were subjected to pooled analysis to investigate the causes of misdiagnosis and seek the measures for reducing misdiagnosis. RESULTS: Fifty-nine studies involving 1178 cases of misdiagnosed pneumoconiosis or silicotuberculosis were collected. There were 13 causes of misdiagnosis, and the most common one was the poor ability of identification due to inadequate experience in reading chest X-ray films (45.93%), followed by neglect of patient's occupational history (44.99%). Other causes of misdiagnosis included complex X-ray findings that are difficult to judge (29.03%), poor quality of chest radiographs (23.09%), and lack of regular health supervision (19.95%). CONCLUSION: Inadequate experience of physicians is the main cause of misdiagnosis of pneumoconiosis or silicotuberculosis. To reduce misdiagnosis of the disease, measures should be taken to enhance the training and evaluation of knowledge and skills of diagnosis and differential diagnosis of pneumoconiosis among physicians.

[A comparative study of the occupational disease list between Taiwan region and the mainland].

OBJECTIVE: To provide technical reference for the revision of the list of occupational diseases of China, the list of occupational diseases between the Taiwan district and the Mainland China have been analyzed and compared. METHODS: Focus on the system of occupational diseases list between the Taiwan district and the Mainland China, the literature analysis and comparative methods were commonly used, and to explore the similarities and differences of the list of occupational diseases between the mainland and Taiwan. RESULTS: The list of occupational diseases between the mainland and Taiwan shows uniformity in the legislative process, the status and role, classification, but exists difference in the enumeration mode, the legal basis of the development, the institutions to develop the list, classification and coverage et al. CONCLUSION: To revise the National List of Occupational Diseases, the socio-economic development requirements should be based on, combined with social security capacity, gradually expand the coverage of occupational diseases, to adapt to the needs of the occupational disease prevention.

[Analysis of qualifications of medical and health institutions and certified doctors for providing occupational disease diagnosis in China].

OBJECTIVE: To investigate the qualifications and current situations of the medical and health institutions and certified doctors for providing occupational disease diagnosis in China and to provide a reference for developing relevant policies. METHODS: Work reports and questionnaires survey were used to investigate the qualifications of all medical and health institutions and certified doctors for providing occupational disease diagnosis in China and their acceptance and diagnosis of occupational disease cases from 2006 to 2010. The rate for the work reports was 100%, and the response rate for the questionnaires was 71.0%. RESULTS: By the end of 2010, in the 31 provincial-level regions (excluding Hong Kong, Macao, and Taiwan) in China, there had been 503 medical and health institutions which were qualified for providing occupational disease diagnosis, including 207 centers for disease control and prevention, accounting for 41.2%, 145 general hospitals, accounting for 28.8%, 69 enterprise-owned hospitals, accounting for 13.7%, and 64 institutes or centers for occupational disease prevention and control, accounting for 12.7%; 4986 certified doctors got the qualification for providing occupational disease diagnosis, with 9.4 certified doctors on average in each institution, and there was 0.65 certified doctor per 100 000 employees. In addition, 16.5% of the institutions got all the qualifications for diagnosing 9 occupational diseases, and 17.1% of the institutions got the qualification for diagnosing one occupational disease. Each certified doctor accepted diagnosis of 16.8 cases of occupational diseases on average every year. CONCLUSION: A national occupational disease diagnosis network has been established in China, but the imbalance in regional distribution and specialty programs still exists among the qualified medical and health institutions and certified doctors. It is essential to further strengthen the development of regional qualified medical and health institutions and training of qualified doctors.

Prediction model based on machine learning for short- and long-term adverse events in left atrial appendage closure.

Background: At present, the prediction of adverse events (AE) had practical significance in clinic and the accuracy of AE prediction model after left atrial appendage closure (LAAC) needed to be improved. To identify a good prediction model based on machine learning for short- and long-term AE after LAAC. Methods: In this study, 869 patients were included from the Department of Cardiovascular Medicine of Shanghai University of Medicine and Health Sciences Affiliated Zhoupu Hospital during 2017 and 2021. Univariate and multivariate analyses were conducted for short-term AE after LAAC to determine possible risk factors related with AE. We compared 8 machine learning algorithms for prediction short-term AE, and XGBoost was found to have the best performance. In addition, Cox-regression was used for long-term AE to find out the risk factors and establish a prediction model. Results: In univariate and multivariate analysis, body mass index (BMI) [odds ratio (OR) =0.91], congestive heart failure, hypertension, age ≥75 years, diabetes, stroke2 attack (CHADS2) score (OR =0.49) and bleeding history or predisposition, labile international normalized ratio (INR), elderly, drug/alcohol usage (BLED) score (OR =1.71) were shown to be significant risk factors for short-term AE. The XGbosst algorithm was used to predict short-term AE based on 15 possible risk factors. For long-term AE, Cox regression was used for the prediction. The CHADS2 score [hazard ratio (HR) =1.43], hypertension (HR =2.18), age more than 75 (HR =0.49), diabetes (HR =0.57), BLED score (HR=0.28), stroke (HR =19.8), hepatopathy (HR =3.97), nephropathy (HR =2.93), INR instability (HR =4.18), drinking (HR =2.67), and drugs (HR =2.36) were significant risk factors for long-term AE. The XGBoost had a good receiver operating characteristic (ROC) curve and area under the curve (AUC) was 0.85. The accuracy of the XGBoost model stayed at nearly 0.95. Conclusions: In short- and long-term AE, CHADS2 score and BLED score were the most obvious risk factors. Several other risk factors also played roles in AE of LAAC. The incidence of long-term AE is under 15% and LAAC is effective and safe. The XGBoost model had good prediction accuracy and ROC curve.

[Clinical analysis of severe/critical 2019 novel coronavirus Omicron variant infection combined with atrial fibrillation].

OBJECTIVE: To investigate the clinical characteristics and prognosis of coronavirus disease 2019 (COVID-19) patients with Omicron variant combined with atrial fibrillation (AF). METHODS: From March 23, 2022 to May 15, 2022, 2 675 aged ≥ 50 years old COVID-19 patients with AF were admitted to Zhoupu Hospital, the designated hospital for COVID-19 in Shanghai. Patients were divided into mild symptoms group, normal group, and serious/critical group according to the symptoms. The clinical data, imaging examination and laboratory results and prognosis of the three group patients were compared. RESULTS: The median age of 2 675 COVID-19 patients was 69.0 (60.0, 81.0) years old, the incidence of AF was 5.05% (135/2 675), the age range of AF patients were from 55 to 101 years old, with a median age of 84.0 (74.0, 89.0), and the number of mild symptoms, normal, serious/critical patients were 68, 30, 37, respectively, including 9 of serious and 28 of critical patients. In the serious/critical patients, aged 55-75 years old accounted for 43.2%, the rate of 2019 novel coronavirus vaccination was 32.4%. The identified new-onset AF was the highest among the three groups, but the rate of persistent AF was the highest in the mild symptoms group (58.8%). The severe/critical group complicated with fever (29.7%), hepatic insufficiency (13.5%), renal insufficiency (46.0%), type 2 diabetes (46.0%), and heart failure were higher in NYHA classification [compared with the mild symptoms and normal group (score): 1.8±1.1 vs. 1.1±0.8, 1.2±0.7, respectively, all P < 0.05]. In term of laboratory examinations, C-reactive protein (CRP), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) levels were significantly higher in serious/critical patients compared to the mild symptoms and normal groups [CRP (mg/L): 27.2 (6.0, 60.8) vs. 7.6 (3.1, 19.3), 12.8 (4.9, 26.3), ALT (U/L): 31.3±15.4 vs. 15.4±9.3, 19.3±11.7, AST (U/L): 78.0±21.7 vs. 34.7±15.6, 38.1±24.4, all P < 0.05]. The hemoglobin (Hb) and albumin (ALB) levels were significantly lower than those in the mild symptoms and normal groups [Hb (g/L): 105.3±22.5 vs. 125.8±25.4, 123.0±20.4, ALB (g/L): 33.7±6.0 vs. 39.0±5.5 and 39.6±13.1, all P < 0.05]. In addition, MB isoenzyme of creatine kinase (CK-MB) was significantly higher in the serious/critical group than that in the mild symptoms group [µg/L: 2.5 (1.5, 3.4) vs. 2.2 (1.2, 2.8), P < 0.05]. In terms of the treatment, the percentage of antiplatelet agents and low-molecular heparin ratio compared among the three groups were statistically significant, with the serious/critical group using the lowest percentage of antiplatelet agents (27.0%) and a higher percentage of low-molecular heparin usage than that in mild symptoms group [81.1% (30/37) vs. 51.5% (35/68), P < 0.05]. In terms of prognosis, the mortality of patients with AF was 18.5% (25/135), all of whom were critical ill, including 32.0% (8/25) with cerebral embolism, pulmonary embolism and cerebral hemorrhage. Among them, 40.0% (10/25) died of multiple organ failure (40.0% combined with gastrointestinal hemorrhage), 20.0% (5/25) died of heart failure, and 12.0% (3/25) died of respiratory failure; while there were no death cases recorded in the mild symptoms, normal group and 9 serious patients. CONCLUSIONS: The serious/critical patients infected with COVID-19 Omicron variant with AF, have a worse prognosis and high mortality. Multiple organ failure, heart failure, sudden cardiac death, respiratory failure and embolic disease are the major causes of death.

[Chronic spontaneous urticaria treated with bloodletting therapy and auricular point sticking on the base of xuanfu theory: a randomized controlled trial].

OBJECTIVE: To compare the clinical therapeutic effect and the impacts on recurrence rate on chronic spontaneous urticaria (CSU) between the combined treatment of bloodletting therapy and auricular point sticking on the base of xuanfu theory and the oral solution of levocetirizine hydrochloride. METHODS: A total of 86 patients with CSU were randomized into an observation group (43 cases, 1 case dropped off) and a control group (43 cases, 3 cases dropped off). In the observation group, bloodletting therapy at Dazhui (GV 14), Feishu (BL 13), Geshu (BL 17) and Pishu (BL 20) was combined with auricular point sticking at lung (CO14), kidney (CO10), shenmen (TF4) and heart (CO15), etc. This combined treatment was given once every two days. In the control group, the oral solution of levocetirizine hydrochloride was prescribed, 10 mL each time, once daily. The treatment lasted for 4 weeks in the two groups. Before and after treatment, urticaria activity score 7 (UAS7), the score of dermatology life quality index (DLQI) and the levels of serum immune globulin E (IgE), interleukin 4 (IL-4) and interferon γ (IFN-γ) were compared in the patients between the two groups. The clinical therapeutic effect was evaluated in patients of the two groups and the recurrence rate was followed up 4, 8 and 12 weeks after treatment separately. RESULTS: After treatment, the scores of UAS7 and DLQI, as well as the levels of serum IgE and IL-4 were all reduced as compared with those before treatment in the two groups (P<0.05), and the level of serum IFN-γ was increased (P<0.05). The total effective rate was 83.3% (35/42) in the observation group and was 85.0% (34/40) in the control group. There was no statistical significance for the difference in the clinical therapeutic effect between the two groups (P>0.05). Eight and 12 weeks after treatment, the recurrence rates were 21.1% (4/19) and 26.3% (5/19) in the observation group, lower than 55.0% (11/20) and 65.0% (13/20) in the control group, respectively (P<0.05). CONCLUSION: The combined therapy of bloodletting and auricular point sticking on the base of xuanfu theory relieves the clinical symptoms, regulates the levels of serum IgE, IL-4 and IFN-γ and improves the quality of life in the patients with CSU. The clinical therapeutic effect of this combined treatment is similar to the oral solution of levocetirizine hydrochloride. But, the recurrence rate of the combined treatment of bloodletting and auricular point sticking is lower and its long-term curative effect is better.

[Pathogenic effects of level of nitric oxide, hyponatremia and heart function on hepatorenal syndrome].

OBJECTIVE: To analyze the changes of liver function, renal function, electrolytes, heart function and serum nitric oxide (NO) in chronic severe hepatitis patients with hepatorenal syndrome (HRS) by plasma exchange (PE), study the relationship of NO, hyponatremia, heart function with HRS. METHODS: A total of 20 chronic severe hepatitis patients with HRS were recruited. All were treated thrice by PE. The parameters of blood pressure, heart rate, 24 h urinary volume, liver function indicators, renal function indicators, NO, cardiac troponin T (cTnT), brain natriuretic peptide (BNP), aldosterone, interleukin-6, tumor necrosis factor-α and plasma ammonia were measured before PE, during PE and after PE. Their differences were compared before, during and after PE. RESULTS: The NO level of HRS before PE was (113 ± 26) µmol/L, the level of Day 1 after PE (78 ± 24) µmol/L and the level of Day 3 after PE was (85 ± 29) µmol/L. All NO levels were lower than that before PE (all P < 0.05). Creatine level of HRS before PE was (191 ± 43) µmol/L and the level of Day 1 after PE (142 ± 42) µmol/L. All levels were lower than that before PE (all P < 0.05). The level of Day 3 after PE was 221 ± 105 µmol/L and it was higher than that before PE (P < 0.05). At pre-, during- and post-PE, the level of sodium was low than normal (normal range: 135 - 145 mmol/L), the level of aldosterone higher than normal (normal range: 10 - 27 ng/L), the level of cTnT higher than normal (normal range: < 14 ng/L) and the level of BNP higher than normal (normal range: < 366 ng/L). The levels of model for end-stage liver disease (MELD) score, bilirubin, urea, cysteine proteinase inhibitor C and ammonia decreased during PE, but increased post-PE. Systolic pressure and 24 h urinary volume decreased gradually. In this study, 8 patients died and 12 were discharged from hospital. CONCLUSION: Serum nitric oxide is not the sole occurring factor for hepatorenal syndrome. Hyponatremia and impaired heart function may be the key factors for hepatorenal syndrome.

Critical exponents of block-block mutual information in one-dimensional infinite lattice systems.

We study the mutual information between two lattice blocks in terms of von Neumann entropies for one-dimensional infinite lattice systems. Quantum q-state Potts model and transverse-field spin-1/2 XY model are considered numerically by using the infinite matrix product state approach. As a system parameter varies, block-block mutual information exhibit singular behaviors that enable us to identify the critical points for the quantum phase transitions. As happens with von Neumann entanglement entropy of single block, at critical points, block-block mutual information for two adjacent blocks show a logarithmic leading behavior with increasing the size of the blocks, which yields the central charge c of the underlying conformal field theory, as it should be. It seems that two disjoint blocks show a similar logarithmic growth of the mutual information as a characteristic property of critical systems but the proportional coefficients of the logarithmic term are very different from the central charges. As the separation between the two lattice blocks increases, the mutual information reveals a consistent power-law decaying behavior for various truncation dimensions and lattice-block sizes. The critical exponent of block-block mutual information in the thermodynamic limit is estimated by extrapolating the exponents of power-law decaying regions for finite truncation dimensions. For a given lattice-block size ℓ, the critical exponents for the same universality classes seem to have very close values each other. Whereas the critical exponents have different values to a degree of distinction for the different universality classes. As the lattice-block size becomes bigger, the critical exponent becomes smaller. We discuss a relation between the exponents of block-block mutual information and correlation with the Shatten one-norm of block-block correlation.

Seroprevalence of IgM and IgG Antibodies against SARS-CoV-2 in Asymptomatic People in Wuhan: Data from a General Hospital Near South China Seafood Wholesale Market during March to April in 2020.

The aim of this study was to estimate the seroprevalence of immunoglobulin M (IgM) and G (IgG) antibodies against SARS-CoV-2 in asymptomatic people in Wuhan. This was a cross-sectional study, which enrolled 18,712 asymptomatic participants from 154 work units in Wuhan. Pearson Chi-square test, t-test, and Mann-Whitney test were used to compare the standardized seroprevalence of IgG and IgM for age and gender between different groups. The results indicated the standardized seroprevalence of IgG and IgM showed a downward trend and was significantly higher among females than males. Besides, different geographic areas and workplaces had different seroprevalence of IgG among asymptomatic people, and the number of abnormalities in CT imaging were higher in IgG antibody-positive cases than IgG-negative cases. We hope these findings can provide references for herd immunity investigation and provide basis for vaccine development.

Analysis of Health Service Utilization and its Influencing Factors among Patients with Pneumoconiosis in China.

Pneumoconiosis, an interstitial lung disease that occurs from breathing in certain kinds of damaging dust particles, is a major occupational disease in China. Patients diagnosed with occupational pneumoconiosis can avail of free medical treatment, whereas patients without a diagnosis of occupational diseases cannot not claim free medical treatment in most provinces from the government before 2019. This study aimed to analyze the priority of medical facility selection and its influencing factors among patients with pneumoconiosis. A total of 1,037 patients with pneumoconiosis from nine provinces in China were investigated. The health service institutions most frequently selected by the patients were county-level hospitals (37.5%). The main reason for the choice was these hospitals' close distance to the patients' homes (47.3%). The factors for the choice of health care institutions were living in the eastern region ( OR = 2.91), living in rural areas ( OR = 2.10), silicosis diagnosis ( OR = 2.44), employment in private enterprises ( OR = 2.91), smoking ( OR = 2.69), and quit smoking ( OR = 3.98). The diagnosis, treatment, and rehabilitation therapy of pneumoconiosis should be enhanced in primary medical institutions.

[Review of occupational hazard census and large-scale surveys in sixty years in China].

OBJECTIVE: To compare and analyze the all previous censuses and large-scale surveys on occupational hazard in China, draw lessons from the past, and try to provide references for the development of census or surveys on the occupational hazard in the new period. METHODS: A literature retrieval had been performed mainly on the occupational hazard census and large-scale surveys since the founding of People's Republic of China. Only the survey items carried on a national scale were selected. Some keywords were drawn from these items such as survey time, survey scope, industries, occupational diseases and the rate of examination, organization and technical director, methods and so on. The outcomes and experiences were summarized. RESULTS: Since the founding of People's Republic of China, there were seven occupational hazard census and large-scale surveys carried in China, three of them were about silicosis or pneumoconiosis, two of them were about poison and carcinogens, one was about noise, another one was about the township industrial enterprises. CONCLUSION: Leadership attention was the fundamental guarantee of the success of the survey, sound occupational health management organizations were the base, collaborative relationship with each other was an import factor, and only the interdisciplinary team, scientific design, quality control and incentive mechanism could assure the quality of the survey. The survey should be designed and carried out according to industries.

Long-distance structural health monitoring of buried pipes using pitch-catch T(0,1) wave piezoelectric ring array transducers.

In modern industries, long-distance guided wave inspection has been routinely used for various types of pipelines. The usage of T(0,1) wave is always of great interests since it is the only non-dispersive wave mode in pipes. In this work, a pair of pitch-catch piezoelectric ring arrays were proposed for long-distance structural health monitoring (SHM) of buried pipes. Firstly, the working principle of the proposed transducer was introduced. Next, the performances of thickness-shear (d15) and face-shear (d24) modes based piezoelectric ring transducers in T(0,1) wave generation and reception were comparatively tested. It was found that at most frequencies, it is best to employ the d15 ring as the exciter and the d24 ring as the receiver. Then, the signal-to-noise ratio (SNR) of the generated T(0,1) wave and its attenuation in pipes with different coating conditions were investigated to estimate the detectable distance using the proposed transducer. Results showed that after applying acoustical isolation layer on pipes, the proposed ring transducers can inspect buried pipes over 20 m. Finally, the performance of the ring transducers in defect detection was validated. This work is expected to provide a promising solution to long-distance SHM of buried pipes.

Quick and repeatable shear modulus measurement based on torsional resonance using a piezoelectric torsional transducer.

Shear modulus is one of the fundamental mechanical properties of materials, while its quick and accurate measurement is still a challenge. Here we proposed a method for shear modulus measurement based on torsional resonance using a piezoelectric torsional transducer bonded on a cylindrical specimen. Firstly, the torsional transducer was introduced which consists of two thickness poled, thickness shear (d15) piezoelectric half-rings. Secondly, the equivalent circuit of the transducer-cylindrical specimen system is derived and the shear modulus can be explicitly obtained using the torsional resonance frequency. The internal friction can also be obtained, which is calculated by using an approximate formula. Then, shear modulus and internal friction measurement on four materials including 1045 steel, 6061 aluminum, quartz glass and PMMA were conducted. Results indicate that all the measured shear moduli are consistent with the reference values in literatures. The repeatable error in shear modulus measurement is within 0.2%, which is very desirable. Finally, shear modulus measurement scheme under high (or low) temperature is proposed using a frequency-match quartz glass bar as the thermal insulator. Measurement results on the 6061 aluminum indicates that from room temperature to 500 °C, the shear modulus decreases from 26.8 GPa to 16.6GPa. The proposed method is very reliable and quite convenient, which can be widely used in near future.

A high-sensitivity and long-distance structural health monitoring system based on bidirectional SH wave phased array.

When estimating a structural health monitoring (SHM) system, its defect sensitivity and area/distance coverage are most important factors. For commonly used guided wave sparse array system, it usually requires a reference state as the baseline which is not available in many cases. In comparison, phased array technique typically does not need the baseline in simple structures and it had been successfully used in nondestructive testing (NDT). However, currently developed phased array systems employed omni-directional transducers routinely, where the wave energy is distributed equally along all directions thus it is not favorable for long-distance detection. In this work, bidirectional piezoelectric transducers were used to form a linear phased array system, which can generate/receive shear horizontal (SH) wave with high energy concentration. Firstly, the configuration of the employed transducer composed by antiparallel d15 piezoelectric strips (APS) was presented. Then the total focusing method (TFM) employed for defect detection was introduced. After validating the radiation pattern of SH wave generated by the APS, the properties of beam steering for the proposed phased array was investigated. Finally, experiments were carried out to validate its performance in detection of various defects. Results indicated that even for a 1 mm through-thickness hole 700 mm away, the proposed phased array system can still detect it accurately, which is much better than previous SHM systems. Dual defects including a crack and a hole can also be clearly detected without baseline. The high-sensitivity of the proposed system was attributed to the employed bidirectional transducer which can generate non-dispersive SH0 wave with high energy concentration. This proposed SH wave phased array system will provide a high-performance SHM method for plate-like structures.