Crack Detection Method for Wind Turbine Tower Bolts Using Ultrasonic Spiral Phased Array.

High-strength bolts are crucial load-bearing components of wind turbine towers. They are highly susceptible to fatigue cracks over long-term service and require timely detection. However, due to the structural complexity and hidden nature of the cracks in wind turbine tower bolts, the small size of the cracks, and their variable propagation directions, detection signals carrying crack information are often drowned out by dense thread signals. Existing non-destructive testing methods are unable to quickly and accurately characterize small cracks at the thread roots. Therefore, we propose an ultrasonic phased array element arrangement method based on the Fermat spiral array. This method can greatly increase the fill rate of the phased array with small element spacing while reducing the effects of grating and sidelobes, thereby achieving high-energy excitation and accurate imaging with the ultrasonic phased array. This has significant theoretical and engineering application value for ensuring the safe and reliable service of key wind turbine components and for promoting the technological development of the wind power industry.

A retrospective analysis of 140 patients with giant cell tumor in the extremity: a multicenter study based on four hospitals in South China.

BACKGROUND: Update reports are rarely available regarding the bone giant cell tumors (GCTs) in the extremity in Chinese people. The aim of this study was to review the epidemiological characteristics of bone GCT in the extremity based on the clinical data from four hospitals in South China. METHODS: We searched medical electronic records from January 2001 to December 2011 in four hospitals in South China to identify patients with definite diagnosis of extremity GCT. Epidemiological data including gender, tumor site, age at the time of first diagnosis, local recurrence and pulmonary metastasis were collected and analyzed statistically. Differences between-genders were particularly analyzed regarding first diagnosis age, tumor site, local recurrence and pulmonary metastasis. T-test and Chi-square test were used for continuous and dichotomous variables, respectively. RESULTS: A total of 140 GCT patients (87 males and 53 females) were identified. The gender ratio was 1.64 for a male predominance. GCTs were mostly located around the knee (67 cases). 92 patients were in their 20s to 40s upon first diagnosis. The average age at the time of first diagnosis for all was 30.49 years, 30.76 years for males and 30.06 years for females (P = 0.757). GCT recurred locally in 50 patients (26 males and 24 females) with no gender difference (P = 0.065). The average interval from first surgery to local recurrence was 21.42 months. Pulmonary metastasis was found in 11 patients (8 males and 3 females) also with no gender difference (P = 0.667). The average interval from first diagnosis to metastasis was 36.45 months. CONCLUSIONS: Extremity GCT may have a male predominance in Chinese population and mostly occur at 20-40 years of age and around the knee. Follow-ups for GCT patients should be carried on for at least 3 years after primary surgery according to the average intervals for possible local recurrence and pulmonary metastasis.

Should displaced midshaft clavicular fractures be treated surgically? A meta-analysis based on current evidence.

PURPOSE: This study was designed to compare clinical effectiveness of operative with nonoperative treatment for displaced midshaft clavicular fractures (DMCF). METHODS: We systematically searched electronic databases (MEDILINE, EMBASE, CLINICAL, OVID, BIOSIS and Cochrane registry of controlled clinical trials) to identify randomized controlled trials (RCTs) in which operative treatment was compared with nonoperative treatment for DMCF from 1980 to 2012. The methodologic quality of trials was assessed. Data from chosen studies were pooled with using of fixed-effects and random-effects models with mean differences and risk ratios for continuous and dichotomous variables, respectively. RESULTS: Four RCTs with a total of 321 patients were screened for the present study. Results showed that the operative treatment was superior to the nonoperative treatment regarding the rate of nonunion [95 % confidence interval (CI) (0.05, 0.43), P = 0.0004], malunion [95 % CI (0.06, 0.34), P < 0.00001] and overall complication [95 % CI (0.43-0.76), P = 0.0001]. Subgroup analyses of complications revealed that significant differences were existed in the incidence of neurologic symptoms [95 % CI (0.20, 0.74), P = 0.004] and dissatisfaction with appearance [95 % CI (0.19, 0.65), P = 0.001]. Lack of consistent and standardized assessment data, insufficiency analysis that carried out showed improved functional outcomes (P < 0.05) in operative treatment. CONCLUSIONS: The available evidence suggests that the operative treatment for DMCF is associated with a lower rate of nonunion, malunion and complication than nonoperative treatment. This study supports traditional primary operative treatment for DMCF in active adults.

Surgical versus nonsurgical treatment of displaced intra-articular calcaneal fracture: a meta-analysis of current evidence base.

PURPOSE: Controversy still surrounds the optimal treatment for patients with displaced intra-articular calcaneal fractures (DIACF). An up-to-date meta-analysis was performed to evaluate clinical effectiveness of surgical treatment for DIACF compared with nonsurgical treatment. METHODS: We systematically searched four electronic databases (Medline, BIOSIS, Cochrane library and Google Scholar) to identify randomised controlled trials (RCTs) and clinical controlled trials (CCTs) in which surgical treatment was compared with nonsurgical treatment of DIACF from 1980 to 2011. Trial quality was assessed using the modified Jadad scale and effective data were pooled for meta-analysis. RESULTS: Ten studies (six RCTs and four CCTs) with a total of 891 participants were screened. Results showed that surgical treatment was superior to nonsurgical treatment in better recovery of the Böhler angle (P < 0.0001), more stable calcaneal height (P = 0.0009) and width (P < 0.00001). Moreover, fewer surgically treated patients needed increased shoe size (P = 0.0004) and more were able to resume pre-injury work (P = 0.004) than the nonsurgical patients. No significant difference was identified between the two methods regarding the incidence of residual pain (P = 0.49). However, operative management was associated with a higher risk of complications (P = 0.008). CONCLUSIONS: Although surgical repair may increase the complication probability, it is the price that has to be paid for better reconstruction of the calcaneus and better functional results. Taken as a whole, surgery is probably the optimal choice in DIACF treatment.